1 /*-------------------------------------------------------------------------
2 *
3 * clauses.c
4 * routines to manipulate qualification clauses
5 *
6 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/optimizer/util/clauses.c
12 *
13 * HISTORY
14 * AUTHOR DATE MAJOR EVENT
15 * Andrew Yu Nov 3, 1994 clause.c and clauses.c combined
16 *
17 *-------------------------------------------------------------------------
18 */
19
20 #include "postgres.h"
21
22 #include "access/htup_details.h"
23 #include "catalog/pg_aggregate.h"
24 #include "catalog/pg_class.h"
25 #include "catalog/pg_language.h"
26 #include "catalog/pg_operator.h"
27 #include "catalog/pg_proc.h"
28 #include "catalog/pg_type.h"
29 #include "executor/executor.h"
30 #include "executor/functions.h"
31 #include "funcapi.h"
32 #include "miscadmin.h"
33 #include "nodes/makefuncs.h"
34 #include "nodes/nodeFuncs.h"
35 #include "nodes/supportnodes.h"
36 #include "optimizer/clauses.h"
37 #include "optimizer/cost.h"
38 #include "optimizer/optimizer.h"
39 #include "optimizer/plancat.h"
40 #include "optimizer/planmain.h"
41 #include "parser/analyze.h"
42 #include "parser/parse_agg.h"
43 #include "parser/parse_coerce.h"
44 #include "parser/parse_func.h"
45 #include "rewrite/rewriteManip.h"
46 #include "tcop/tcopprot.h"
47 #include "utils/acl.h"
48 #include "utils/builtins.h"
49 #include "utils/datum.h"
50 #include "utils/fmgroids.h"
51 #include "utils/lsyscache.h"
52 #include "utils/memutils.h"
53 #include "utils/syscache.h"
54 #include "utils/typcache.h"
55
56
57 /* source-code-compatibility hacks for pull_varnos() API change */
58 #define pull_varnos(a,b) pull_varnos_new(a,b)
59
60 typedef struct
61 {
62 PlannerInfo *root;
63 AggSplit aggsplit;
64 AggClauseCosts *costs;
65 } get_agg_clause_costs_context;
66
67 typedef struct
68 {
69 ParamListInfo boundParams;
70 PlannerInfo *root;
71 List *active_fns;
72 Node *case_val;
73 bool estimate;
74 } eval_const_expressions_context;
75
76 typedef struct
77 {
78 int nargs;
79 List *args;
80 int *usecounts;
81 } substitute_actual_parameters_context;
82
83 typedef struct
84 {
85 int nargs;
86 List *args;
87 int sublevels_up;
88 } substitute_actual_srf_parameters_context;
89
90 typedef struct
91 {
92 char *proname;
93 char *prosrc;
94 } inline_error_callback_arg;
95
96 typedef struct
97 {
98 char max_hazard; /* worst proparallel hazard found so far */
99 char max_interesting; /* worst proparallel hazard of interest */
100 List *safe_param_ids; /* PARAM_EXEC Param IDs to treat as safe */
101 } max_parallel_hazard_context;
102
103 static bool contain_agg_clause_walker(Node *node, void *context);
104 static bool get_agg_clause_costs_walker(Node *node,
105 get_agg_clause_costs_context *context);
106 static bool find_window_functions_walker(Node *node, WindowFuncLists *lists);
107 static bool contain_subplans_walker(Node *node, void *context);
108 static bool contain_mutable_functions_walker(Node *node, void *context);
109 static bool contain_volatile_functions_walker(Node *node, void *context);
110 static bool contain_volatile_functions_not_nextval_walker(Node *node, void *context);
111 static bool max_parallel_hazard_walker(Node *node,
112 max_parallel_hazard_context *context);
113 static bool contain_nonstrict_functions_walker(Node *node, void *context);
114 static bool contain_exec_param_walker(Node *node, List *param_ids);
115 static bool contain_context_dependent_node(Node *clause);
116 static bool contain_context_dependent_node_walker(Node *node, int *flags);
117 static bool contain_leaked_vars_walker(Node *node, void *context);
118 static Relids find_nonnullable_rels_walker(Node *node, bool top_level);
119 static List *find_nonnullable_vars_walker(Node *node, bool top_level);
120 static bool is_strict_saop(ScalarArrayOpExpr *expr, bool falseOK);
121 static Node *eval_const_expressions_mutator(Node *node,
122 eval_const_expressions_context *context);
123 static bool contain_non_const_walker(Node *node, void *context);
124 static bool ece_function_is_safe(Oid funcid,
125 eval_const_expressions_context *context);
126 static List *simplify_or_arguments(List *args,
127 eval_const_expressions_context *context,
128 bool *haveNull, bool *forceTrue);
129 static List *simplify_and_arguments(List *args,
130 eval_const_expressions_context *context,
131 bool *haveNull, bool *forceFalse);
132 static Node *simplify_boolean_equality(Oid opno, List *args);
133 static Expr *simplify_function(Oid funcid,
134 Oid result_type, int32 result_typmod,
135 Oid result_collid, Oid input_collid, List **args_p,
136 bool funcvariadic, bool process_args, bool allow_non_const,
137 eval_const_expressions_context *context);
138 static List *reorder_function_arguments(List *args, HeapTuple func_tuple);
139 static List *add_function_defaults(List *args, HeapTuple func_tuple);
140 static List *fetch_function_defaults(HeapTuple func_tuple);
141 static void recheck_cast_function_args(List *args, Oid result_type,
142 HeapTuple func_tuple);
143 static Expr *evaluate_function(Oid funcid, Oid result_type, int32 result_typmod,
144 Oid result_collid, Oid input_collid, List *args,
145 bool funcvariadic,
146 HeapTuple func_tuple,
147 eval_const_expressions_context *context);
148 static Expr *inline_function(Oid funcid, Oid result_type, Oid result_collid,
149 Oid input_collid, List *args,
150 bool funcvariadic,
151 HeapTuple func_tuple,
152 eval_const_expressions_context *context);
153 static Node *substitute_actual_parameters(Node *expr, int nargs, List *args,
154 int *usecounts);
155 static Node *substitute_actual_parameters_mutator(Node *node,
156 substitute_actual_parameters_context *context);
157 static void sql_inline_error_callback(void *arg);
158 static Query *substitute_actual_srf_parameters(Query *expr,
159 int nargs, List *args);
160 static Node *substitute_actual_srf_parameters_mutator(Node *node,
161 substitute_actual_srf_parameters_context *context);
162
163
164 /*****************************************************************************
165 * Aggregate-function clause manipulation
166 *****************************************************************************/
167
168 /*
169 * contain_agg_clause
170 * Recursively search for Aggref/GroupingFunc nodes within a clause.
171 *
172 * Returns true if any aggregate found.
173 *
174 * This does not descend into subqueries, and so should be used only after
175 * reduction of sublinks to subplans, or in contexts where it's known there
176 * are no subqueries. There mustn't be outer-aggregate references either.
177 *
178 * (If you want something like this but able to deal with subqueries,
179 * see rewriteManip.c's contain_aggs_of_level().)
180 */
181 bool
contain_agg_clause(Node * clause)182 contain_agg_clause(Node *clause)
183 {
184 return contain_agg_clause_walker(clause, NULL);
185 }
186
187 static bool
contain_agg_clause_walker(Node * node,void * context)188 contain_agg_clause_walker(Node *node, void *context)
189 {
190 if (node == NULL)
191 return false;
192 if (IsA(node, Aggref))
193 {
194 Assert(((Aggref *) node)->agglevelsup == 0);
195 return true; /* abort the tree traversal and return true */
196 }
197 if (IsA(node, GroupingFunc))
198 {
199 Assert(((GroupingFunc *) node)->agglevelsup == 0);
200 return true; /* abort the tree traversal and return true */
201 }
202 Assert(!IsA(node, SubLink));
203 return expression_tree_walker(node, contain_agg_clause_walker, context);
204 }
205
206 /*
207 * get_agg_clause_costs
208 * Recursively find the Aggref nodes in an expression tree, and
209 * accumulate cost information about them.
210 *
211 * 'aggsplit' tells us the expected partial-aggregation mode, which affects
212 * the cost estimates.
213 *
214 * NOTE that the counts/costs are ADDED to those already in *costs ... so
215 * the caller is responsible for zeroing the struct initially.
216 *
217 * We count the nodes, estimate their execution costs, and estimate the total
218 * space needed for their transition state values if all are evaluated in
219 * parallel (as would be done in a HashAgg plan). Also, we check whether
220 * partial aggregation is feasible. See AggClauseCosts for the exact set
221 * of statistics collected.
222 *
223 * In addition, we mark Aggref nodes with the correct aggtranstype, so
224 * that that doesn't need to be done repeatedly. (That makes this function's
225 * name a bit of a misnomer.)
226 *
227 * This does not descend into subqueries, and so should be used only after
228 * reduction of sublinks to subplans, or in contexts where it's known there
229 * are no subqueries. There mustn't be outer-aggregate references either.
230 */
231 void
get_agg_clause_costs(PlannerInfo * root,Node * clause,AggSplit aggsplit,AggClauseCosts * costs)232 get_agg_clause_costs(PlannerInfo *root, Node *clause, AggSplit aggsplit,
233 AggClauseCosts *costs)
234 {
235 get_agg_clause_costs_context context;
236
237 context.root = root;
238 context.aggsplit = aggsplit;
239 context.costs = costs;
240 (void) get_agg_clause_costs_walker(clause, &context);
241 }
242
243 static bool
get_agg_clause_costs_walker(Node * node,get_agg_clause_costs_context * context)244 get_agg_clause_costs_walker(Node *node, get_agg_clause_costs_context *context)
245 {
246 if (node == NULL)
247 return false;
248 if (IsA(node, Aggref))
249 {
250 Aggref *aggref = (Aggref *) node;
251 AggClauseCosts *costs = context->costs;
252 HeapTuple aggTuple;
253 Form_pg_aggregate aggform;
254 Oid aggtransfn;
255 Oid aggfinalfn;
256 Oid aggcombinefn;
257 Oid aggserialfn;
258 Oid aggdeserialfn;
259 Oid aggtranstype;
260 int32 aggtransspace;
261 QualCost argcosts;
262
263 Assert(aggref->agglevelsup == 0);
264
265 /*
266 * Fetch info about aggregate from pg_aggregate. Note it's correct to
267 * ignore the moving-aggregate variant, since what we're concerned
268 * with here is aggregates not window functions.
269 */
270 aggTuple = SearchSysCache1(AGGFNOID,
271 ObjectIdGetDatum(aggref->aggfnoid));
272 if (!HeapTupleIsValid(aggTuple))
273 elog(ERROR, "cache lookup failed for aggregate %u",
274 aggref->aggfnoid);
275 aggform = (Form_pg_aggregate) GETSTRUCT(aggTuple);
276 aggtransfn = aggform->aggtransfn;
277 aggfinalfn = aggform->aggfinalfn;
278 aggcombinefn = aggform->aggcombinefn;
279 aggserialfn = aggform->aggserialfn;
280 aggdeserialfn = aggform->aggdeserialfn;
281 aggtranstype = aggform->aggtranstype;
282 aggtransspace = aggform->aggtransspace;
283 ReleaseSysCache(aggTuple);
284
285 /*
286 * Resolve the possibly-polymorphic aggregate transition type, unless
287 * already done in a previous pass over the expression.
288 */
289 if (OidIsValid(aggref->aggtranstype))
290 aggtranstype = aggref->aggtranstype;
291 else
292 {
293 Oid inputTypes[FUNC_MAX_ARGS];
294 int numArguments;
295
296 /* extract argument types (ignoring any ORDER BY expressions) */
297 numArguments = get_aggregate_argtypes(aggref, inputTypes);
298
299 /* resolve actual type of transition state, if polymorphic */
300 aggtranstype = resolve_aggregate_transtype(aggref->aggfnoid,
301 aggtranstype,
302 inputTypes,
303 numArguments);
304 aggref->aggtranstype = aggtranstype;
305 }
306
307 /*
308 * Count it, and check for cases requiring ordered input. Note that
309 * ordered-set aggs always have nonempty aggorder. Any ordered-input
310 * case also defeats partial aggregation.
311 */
312 costs->numAggs++;
313 if (aggref->aggorder != NIL || aggref->aggdistinct != NIL)
314 {
315 costs->numOrderedAggs++;
316 costs->hasNonPartial = true;
317 }
318
319 /*
320 * Check whether partial aggregation is feasible, unless we already
321 * found out that we can't do it.
322 */
323 if (!costs->hasNonPartial)
324 {
325 /*
326 * If there is no combine function, then partial aggregation is
327 * not possible.
328 */
329 if (!OidIsValid(aggcombinefn))
330 costs->hasNonPartial = true;
331
332 /*
333 * If we have any aggs with transtype INTERNAL then we must check
334 * whether they have serialization/deserialization functions; if
335 * not, we can't serialize partial-aggregation results.
336 */
337 else if (aggtranstype == INTERNALOID &&
338 (!OidIsValid(aggserialfn) || !OidIsValid(aggdeserialfn)))
339 costs->hasNonSerial = true;
340 }
341
342 /*
343 * Add the appropriate component function execution costs to
344 * appropriate totals.
345 */
346 if (DO_AGGSPLIT_COMBINE(context->aggsplit))
347 {
348 /* charge for combining previously aggregated states */
349 add_function_cost(context->root, aggcombinefn, NULL,
350 &costs->transCost);
351 }
352 else
353 add_function_cost(context->root, aggtransfn, NULL,
354 &costs->transCost);
355 if (DO_AGGSPLIT_DESERIALIZE(context->aggsplit) &&
356 OidIsValid(aggdeserialfn))
357 add_function_cost(context->root, aggdeserialfn, NULL,
358 &costs->transCost);
359 if (DO_AGGSPLIT_SERIALIZE(context->aggsplit) &&
360 OidIsValid(aggserialfn))
361 add_function_cost(context->root, aggserialfn, NULL,
362 &costs->finalCost);
363 if (!DO_AGGSPLIT_SKIPFINAL(context->aggsplit) &&
364 OidIsValid(aggfinalfn))
365 add_function_cost(context->root, aggfinalfn, NULL,
366 &costs->finalCost);
367
368 /*
369 * These costs are incurred only by the initial aggregate node, so we
370 * mustn't include them again at upper levels.
371 */
372 if (!DO_AGGSPLIT_COMBINE(context->aggsplit))
373 {
374 /* add the input expressions' cost to per-input-row costs */
375 cost_qual_eval_node(&argcosts, (Node *) aggref->args, context->root);
376 costs->transCost.startup += argcosts.startup;
377 costs->transCost.per_tuple += argcosts.per_tuple;
378
379 /*
380 * Add any filter's cost to per-input-row costs.
381 *
382 * XXX Ideally we should reduce input expression costs according
383 * to filter selectivity, but it's not clear it's worth the
384 * trouble.
385 */
386 if (aggref->aggfilter)
387 {
388 cost_qual_eval_node(&argcosts, (Node *) aggref->aggfilter,
389 context->root);
390 costs->transCost.startup += argcosts.startup;
391 costs->transCost.per_tuple += argcosts.per_tuple;
392 }
393 }
394
395 /*
396 * If there are direct arguments, treat their evaluation cost like the
397 * cost of the finalfn.
398 */
399 if (aggref->aggdirectargs)
400 {
401 cost_qual_eval_node(&argcosts, (Node *) aggref->aggdirectargs,
402 context->root);
403 costs->finalCost.startup += argcosts.startup;
404 costs->finalCost.per_tuple += argcosts.per_tuple;
405 }
406
407 /*
408 * If the transition type is pass-by-value then it doesn't add
409 * anything to the required size of the hashtable. If it is
410 * pass-by-reference then we have to add the estimated size of the
411 * value itself, plus palloc overhead.
412 */
413 if (!get_typbyval(aggtranstype))
414 {
415 int32 avgwidth;
416
417 /* Use average width if aggregate definition gave one */
418 if (aggtransspace > 0)
419 avgwidth = aggtransspace;
420 else if (aggtransfn == F_ARRAY_APPEND)
421 {
422 /*
423 * If the transition function is array_append(), it'll use an
424 * expanded array as transvalue, which will occupy at least
425 * ALLOCSET_SMALL_INITSIZE and possibly more. Use that as the
426 * estimate for lack of a better idea.
427 */
428 avgwidth = ALLOCSET_SMALL_INITSIZE;
429 }
430 else
431 {
432 /*
433 * If transition state is of same type as first aggregated
434 * input, assume it's the same typmod (same width) as well.
435 * This works for cases like MAX/MIN and is probably somewhat
436 * reasonable otherwise.
437 */
438 int32 aggtranstypmod = -1;
439
440 if (aggref->args)
441 {
442 TargetEntry *tle = (TargetEntry *) linitial(aggref->args);
443
444 if (aggtranstype == exprType((Node *) tle->expr))
445 aggtranstypmod = exprTypmod((Node *) tle->expr);
446 }
447
448 avgwidth = get_typavgwidth(aggtranstype, aggtranstypmod);
449 }
450
451 avgwidth = MAXALIGN(avgwidth);
452 costs->transitionSpace += avgwidth + 2 * sizeof(void *);
453 }
454 else if (aggtranstype == INTERNALOID)
455 {
456 /*
457 * INTERNAL transition type is a special case: although INTERNAL
458 * is pass-by-value, it's almost certainly being used as a pointer
459 * to some large data structure. The aggregate definition can
460 * provide an estimate of the size. If it doesn't, then we assume
461 * ALLOCSET_DEFAULT_INITSIZE, which is a good guess if the data is
462 * being kept in a private memory context, as is done by
463 * array_agg() for instance.
464 */
465 if (aggtransspace > 0)
466 costs->transitionSpace += aggtransspace;
467 else
468 costs->transitionSpace += ALLOCSET_DEFAULT_INITSIZE;
469 }
470
471 /*
472 * We assume that the parser checked that there are no aggregates (of
473 * this level anyway) in the aggregated arguments, direct arguments,
474 * or filter clause. Hence, we need not recurse into any of them.
475 */
476 return false;
477 }
478 Assert(!IsA(node, SubLink));
479 return expression_tree_walker(node, get_agg_clause_costs_walker,
480 (void *) context);
481 }
482
483
484 /*****************************************************************************
485 * Window-function clause manipulation
486 *****************************************************************************/
487
488 /*
489 * contain_window_function
490 * Recursively search for WindowFunc nodes within a clause.
491 *
492 * Since window functions don't have level fields, but are hard-wired to
493 * be associated with the current query level, this is just the same as
494 * rewriteManip.c's function.
495 */
496 bool
contain_window_function(Node * clause)497 contain_window_function(Node *clause)
498 {
499 return contain_windowfuncs(clause);
500 }
501
502 /*
503 * find_window_functions
504 * Locate all the WindowFunc nodes in an expression tree, and organize
505 * them by winref ID number.
506 *
507 * Caller must provide an upper bound on the winref IDs expected in the tree.
508 */
509 WindowFuncLists *
find_window_functions(Node * clause,Index maxWinRef)510 find_window_functions(Node *clause, Index maxWinRef)
511 {
512 WindowFuncLists *lists = palloc(sizeof(WindowFuncLists));
513
514 lists->numWindowFuncs = 0;
515 lists->maxWinRef = maxWinRef;
516 lists->windowFuncs = (List **) palloc0((maxWinRef + 1) * sizeof(List *));
517 (void) find_window_functions_walker(clause, lists);
518 return lists;
519 }
520
521 static bool
find_window_functions_walker(Node * node,WindowFuncLists * lists)522 find_window_functions_walker(Node *node, WindowFuncLists *lists)
523 {
524 if (node == NULL)
525 return false;
526 if (IsA(node, WindowFunc))
527 {
528 WindowFunc *wfunc = (WindowFunc *) node;
529
530 /* winref is unsigned, so one-sided test is OK */
531 if (wfunc->winref > lists->maxWinRef)
532 elog(ERROR, "WindowFunc contains out-of-range winref %u",
533 wfunc->winref);
534 /* eliminate duplicates, so that we avoid repeated computation */
535 if (!list_member(lists->windowFuncs[wfunc->winref], wfunc))
536 {
537 lists->windowFuncs[wfunc->winref] =
538 lappend(lists->windowFuncs[wfunc->winref], wfunc);
539 lists->numWindowFuncs++;
540 }
541
542 /*
543 * We assume that the parser checked that there are no window
544 * functions in the arguments or filter clause. Hence, we need not
545 * recurse into them. (If either the parser or the planner screws up
546 * on this point, the executor will still catch it; see ExecInitExpr.)
547 */
548 return false;
549 }
550 Assert(!IsA(node, SubLink));
551 return expression_tree_walker(node, find_window_functions_walker,
552 (void *) lists);
553 }
554
555
556 /*****************************************************************************
557 * Support for expressions returning sets
558 *****************************************************************************/
559
560 /*
561 * expression_returns_set_rows
562 * Estimate the number of rows returned by a set-returning expression.
563 * The result is 1 if it's not a set-returning expression.
564 *
565 * We should only examine the top-level function or operator; it used to be
566 * appropriate to recurse, but not anymore. (Even if there are more SRFs in
567 * the function's inputs, their multipliers are accounted for separately.)
568 *
569 * Note: keep this in sync with expression_returns_set() in nodes/nodeFuncs.c.
570 */
571 double
expression_returns_set_rows(PlannerInfo * root,Node * clause)572 expression_returns_set_rows(PlannerInfo *root, Node *clause)
573 {
574 if (clause == NULL)
575 return 1.0;
576 if (IsA(clause, FuncExpr))
577 {
578 FuncExpr *expr = (FuncExpr *) clause;
579
580 if (expr->funcretset)
581 return clamp_row_est(get_function_rows(root, expr->funcid, clause));
582 }
583 if (IsA(clause, OpExpr))
584 {
585 OpExpr *expr = (OpExpr *) clause;
586
587 if (expr->opretset)
588 {
589 set_opfuncid(expr);
590 return clamp_row_est(get_function_rows(root, expr->opfuncid, clause));
591 }
592 }
593 return 1.0;
594 }
595
596
597 /*****************************************************************************
598 * Subplan clause manipulation
599 *****************************************************************************/
600
601 /*
602 * contain_subplans
603 * Recursively search for subplan nodes within a clause.
604 *
605 * If we see a SubLink node, we will return true. This is only possible if
606 * the expression tree hasn't yet been transformed by subselect.c. We do not
607 * know whether the node will produce a true subplan or just an initplan,
608 * but we make the conservative assumption that it will be a subplan.
609 *
610 * Returns true if any subplan found.
611 */
612 bool
contain_subplans(Node * clause)613 contain_subplans(Node *clause)
614 {
615 return contain_subplans_walker(clause, NULL);
616 }
617
618 static bool
contain_subplans_walker(Node * node,void * context)619 contain_subplans_walker(Node *node, void *context)
620 {
621 if (node == NULL)
622 return false;
623 if (IsA(node, SubPlan) ||
624 IsA(node, AlternativeSubPlan) ||
625 IsA(node, SubLink))
626 return true; /* abort the tree traversal and return true */
627 return expression_tree_walker(node, contain_subplans_walker, context);
628 }
629
630
631 /*****************************************************************************
632 * Check clauses for mutable functions
633 *****************************************************************************/
634
635 /*
636 * contain_mutable_functions
637 * Recursively search for mutable functions within a clause.
638 *
639 * Returns true if any mutable function (or operator implemented by a
640 * mutable function) is found. This test is needed so that we don't
641 * mistakenly think that something like "WHERE random() < 0.5" can be treated
642 * as a constant qualification.
643 *
644 * We will recursively look into Query nodes (i.e., SubLink sub-selects)
645 * but not into SubPlans. See comments for contain_volatile_functions().
646 */
647 bool
contain_mutable_functions(Node * clause)648 contain_mutable_functions(Node *clause)
649 {
650 return contain_mutable_functions_walker(clause, NULL);
651 }
652
653 static bool
contain_mutable_functions_checker(Oid func_id,void * context)654 contain_mutable_functions_checker(Oid func_id, void *context)
655 {
656 return (func_volatile(func_id) != PROVOLATILE_IMMUTABLE);
657 }
658
659 static bool
contain_mutable_functions_walker(Node * node,void * context)660 contain_mutable_functions_walker(Node *node, void *context)
661 {
662 if (node == NULL)
663 return false;
664 /* Check for mutable functions in node itself */
665 if (check_functions_in_node(node, contain_mutable_functions_checker,
666 context))
667 return true;
668
669 if (IsA(node, SQLValueFunction))
670 {
671 /* all variants of SQLValueFunction are stable */
672 return true;
673 }
674
675 if (IsA(node, NextValueExpr))
676 {
677 /* NextValueExpr is volatile */
678 return true;
679 }
680
681 /*
682 * It should be safe to treat MinMaxExpr as immutable, because it will
683 * depend on a non-cross-type btree comparison function, and those should
684 * always be immutable. Treating XmlExpr as immutable is more dubious,
685 * and treating CoerceToDomain as immutable is outright dangerous. But we
686 * have done so historically, and changing this would probably cause more
687 * problems than it would fix. In practice, if you have a non-immutable
688 * domain constraint you are in for pain anyhow.
689 */
690
691 /* Recurse to check arguments */
692 if (IsA(node, Query))
693 {
694 /* Recurse into subselects */
695 return query_tree_walker((Query *) node,
696 contain_mutable_functions_walker,
697 context, 0);
698 }
699 return expression_tree_walker(node, contain_mutable_functions_walker,
700 context);
701 }
702
703
704 /*****************************************************************************
705 * Check clauses for volatile functions
706 *****************************************************************************/
707
708 /*
709 * contain_volatile_functions
710 * Recursively search for volatile functions within a clause.
711 *
712 * Returns true if any volatile function (or operator implemented by a
713 * volatile function) is found. This test prevents, for example,
714 * invalid conversions of volatile expressions into indexscan quals.
715 *
716 * We will recursively look into Query nodes (i.e., SubLink sub-selects)
717 * but not into SubPlans. This is a bit odd, but intentional. If we are
718 * looking at a SubLink, we are probably deciding whether a query tree
719 * transformation is safe, and a contained sub-select should affect that;
720 * for example, duplicating a sub-select containing a volatile function
721 * would be bad. However, once we've got to the stage of having SubPlans,
722 * subsequent planning need not consider volatility within those, since
723 * the executor won't change its evaluation rules for a SubPlan based on
724 * volatility.
725 */
726 bool
contain_volatile_functions(Node * clause)727 contain_volatile_functions(Node *clause)
728 {
729 return contain_volatile_functions_walker(clause, NULL);
730 }
731
732 static bool
contain_volatile_functions_checker(Oid func_id,void * context)733 contain_volatile_functions_checker(Oid func_id, void *context)
734 {
735 return (func_volatile(func_id) == PROVOLATILE_VOLATILE);
736 }
737
738 static bool
contain_volatile_functions_walker(Node * node,void * context)739 contain_volatile_functions_walker(Node *node, void *context)
740 {
741 if (node == NULL)
742 return false;
743 /* Check for volatile functions in node itself */
744 if (check_functions_in_node(node, contain_volatile_functions_checker,
745 context))
746 return true;
747
748 if (IsA(node, NextValueExpr))
749 {
750 /* NextValueExpr is volatile */
751 return true;
752 }
753
754 /*
755 * See notes in contain_mutable_functions_walker about why we treat
756 * MinMaxExpr, XmlExpr, and CoerceToDomain as immutable, while
757 * SQLValueFunction is stable. Hence, none of them are of interest here.
758 */
759
760 /* Recurse to check arguments */
761 if (IsA(node, Query))
762 {
763 /* Recurse into subselects */
764 return query_tree_walker((Query *) node,
765 contain_volatile_functions_walker,
766 context, 0);
767 }
768 return expression_tree_walker(node, contain_volatile_functions_walker,
769 context);
770 }
771
772 /*
773 * Special purpose version of contain_volatile_functions() for use in COPY:
774 * ignore nextval(), but treat all other functions normally.
775 */
776 bool
contain_volatile_functions_not_nextval(Node * clause)777 contain_volatile_functions_not_nextval(Node *clause)
778 {
779 return contain_volatile_functions_not_nextval_walker(clause, NULL);
780 }
781
782 static bool
contain_volatile_functions_not_nextval_checker(Oid func_id,void * context)783 contain_volatile_functions_not_nextval_checker(Oid func_id, void *context)
784 {
785 return (func_id != F_NEXTVAL_OID &&
786 func_volatile(func_id) == PROVOLATILE_VOLATILE);
787 }
788
789 static bool
contain_volatile_functions_not_nextval_walker(Node * node,void * context)790 contain_volatile_functions_not_nextval_walker(Node *node, void *context)
791 {
792 if (node == NULL)
793 return false;
794 /* Check for volatile functions in node itself */
795 if (check_functions_in_node(node,
796 contain_volatile_functions_not_nextval_checker,
797 context))
798 return true;
799
800 /*
801 * See notes in contain_mutable_functions_walker about why we treat
802 * MinMaxExpr, XmlExpr, and CoerceToDomain as immutable, while
803 * SQLValueFunction is stable. Hence, none of them are of interest here.
804 * Also, since we're intentionally ignoring nextval(), presumably we
805 * should ignore NextValueExpr.
806 */
807
808 /* Recurse to check arguments */
809 if (IsA(node, Query))
810 {
811 /* Recurse into subselects */
812 return query_tree_walker((Query *) node,
813 contain_volatile_functions_not_nextval_walker,
814 context, 0);
815 }
816 return expression_tree_walker(node,
817 contain_volatile_functions_not_nextval_walker,
818 context);
819 }
820
821
822 /*****************************************************************************
823 * Check queries for parallel unsafe and/or restricted constructs
824 *****************************************************************************/
825
826 /*
827 * max_parallel_hazard
828 * Find the worst parallel-hazard level in the given query
829 *
830 * Returns the worst function hazard property (the earliest in this list:
831 * PROPARALLEL_UNSAFE, PROPARALLEL_RESTRICTED, PROPARALLEL_SAFE) that can
832 * be found in the given parsetree. We use this to find out whether the query
833 * can be parallelized at all. The caller will also save the result in
834 * PlannerGlobal so as to short-circuit checks of portions of the querytree
835 * later, in the common case where everything is SAFE.
836 */
837 char
max_parallel_hazard(Query * parse)838 max_parallel_hazard(Query *parse)
839 {
840 max_parallel_hazard_context context;
841
842 context.max_hazard = PROPARALLEL_SAFE;
843 context.max_interesting = PROPARALLEL_UNSAFE;
844 context.safe_param_ids = NIL;
845 (void) max_parallel_hazard_walker((Node *) parse, &context);
846 return context.max_hazard;
847 }
848
849 /*
850 * is_parallel_safe
851 * Detect whether the given expr contains only parallel-safe functions
852 *
853 * root->glob->maxParallelHazard must previously have been set to the
854 * result of max_parallel_hazard() on the whole query.
855 */
856 bool
is_parallel_safe(PlannerInfo * root,Node * node)857 is_parallel_safe(PlannerInfo *root, Node *node)
858 {
859 max_parallel_hazard_context context;
860 PlannerInfo *proot;
861 ListCell *l;
862
863 /*
864 * Even if the original querytree contained nothing unsafe, we need to
865 * search the expression if we have generated any PARAM_EXEC Params while
866 * planning, because those are parallel-restricted and there might be one
867 * in this expression. But otherwise we don't need to look.
868 */
869 if (root->glob->maxParallelHazard == PROPARALLEL_SAFE &&
870 root->glob->paramExecTypes == NIL)
871 return true;
872 /* Else use max_parallel_hazard's search logic, but stop on RESTRICTED */
873 context.max_hazard = PROPARALLEL_SAFE;
874 context.max_interesting = PROPARALLEL_RESTRICTED;
875 context.safe_param_ids = NIL;
876
877 /*
878 * The params that refer to the same or parent query level are considered
879 * parallel-safe. The idea is that we compute such params at Gather or
880 * Gather Merge node and pass their value to workers.
881 */
882 for (proot = root; proot != NULL; proot = proot->parent_root)
883 {
884 foreach(l, proot->init_plans)
885 {
886 SubPlan *initsubplan = (SubPlan *) lfirst(l);
887
888 context.safe_param_ids = list_concat(context.safe_param_ids,
889 initsubplan->setParam);
890 }
891 }
892
893 return !max_parallel_hazard_walker(node, &context);
894 }
895
896 /* core logic for all parallel-hazard checks */
897 static bool
max_parallel_hazard_test(char proparallel,max_parallel_hazard_context * context)898 max_parallel_hazard_test(char proparallel, max_parallel_hazard_context *context)
899 {
900 switch (proparallel)
901 {
902 case PROPARALLEL_SAFE:
903 /* nothing to see here, move along */
904 break;
905 case PROPARALLEL_RESTRICTED:
906 /* increase max_hazard to RESTRICTED */
907 Assert(context->max_hazard != PROPARALLEL_UNSAFE);
908 context->max_hazard = proparallel;
909 /* done if we are not expecting any unsafe functions */
910 if (context->max_interesting == proparallel)
911 return true;
912 break;
913 case PROPARALLEL_UNSAFE:
914 context->max_hazard = proparallel;
915 /* we're always done at the first unsafe construct */
916 return true;
917 default:
918 elog(ERROR, "unrecognized proparallel value \"%c\"", proparallel);
919 break;
920 }
921 return false;
922 }
923
924 /* check_functions_in_node callback */
925 static bool
max_parallel_hazard_checker(Oid func_id,void * context)926 max_parallel_hazard_checker(Oid func_id, void *context)
927 {
928 return max_parallel_hazard_test(func_parallel(func_id),
929 (max_parallel_hazard_context *) context);
930 }
931
932 static bool
max_parallel_hazard_walker(Node * node,max_parallel_hazard_context * context)933 max_parallel_hazard_walker(Node *node, max_parallel_hazard_context *context)
934 {
935 if (node == NULL)
936 return false;
937
938 /* Check for hazardous functions in node itself */
939 if (check_functions_in_node(node, max_parallel_hazard_checker,
940 context))
941 return true;
942
943 /*
944 * It should be OK to treat MinMaxExpr as parallel-safe, since btree
945 * opclass support functions are generally parallel-safe. XmlExpr is a
946 * bit more dubious but we can probably get away with it. We err on the
947 * side of caution by treating CoerceToDomain as parallel-restricted.
948 * (Note: in principle that's wrong because a domain constraint could
949 * contain a parallel-unsafe function; but useful constraints probably
950 * never would have such, and assuming they do would cripple use of
951 * parallel query in the presence of domain types.) SQLValueFunction
952 * should be safe in all cases. NextValueExpr is parallel-unsafe.
953 */
954 if (IsA(node, CoerceToDomain))
955 {
956 if (max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
957 return true;
958 }
959
960 else if (IsA(node, NextValueExpr))
961 {
962 if (max_parallel_hazard_test(PROPARALLEL_UNSAFE, context))
963 return true;
964 }
965
966 /*
967 * Treat window functions as parallel-restricted because we aren't sure
968 * whether the input row ordering is fully deterministic, and the output
969 * of window functions might vary across workers if not. (In some cases,
970 * like where the window frame orders by a primary key, we could relax
971 * this restriction. But it doesn't currently seem worth expending extra
972 * effort to do so.)
973 */
974 else if (IsA(node, WindowFunc))
975 {
976 if (max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
977 return true;
978 }
979
980 /*
981 * As a notational convenience for callers, look through RestrictInfo.
982 */
983 else if (IsA(node, RestrictInfo))
984 {
985 RestrictInfo *rinfo = (RestrictInfo *) node;
986
987 return max_parallel_hazard_walker((Node *) rinfo->clause, context);
988 }
989
990 /*
991 * Really we should not see SubLink during a max_interesting == restricted
992 * scan, but if we do, return true.
993 */
994 else if (IsA(node, SubLink))
995 {
996 if (max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
997 return true;
998 }
999
1000 /*
1001 * Only parallel-safe SubPlans can be sent to workers. Within the
1002 * testexpr of the SubPlan, Params representing the output columns of the
1003 * subplan can be treated as parallel-safe, so temporarily add their IDs
1004 * to the safe_param_ids list while examining the testexpr.
1005 */
1006 else if (IsA(node, SubPlan))
1007 {
1008 SubPlan *subplan = (SubPlan *) node;
1009 List *save_safe_param_ids;
1010
1011 if (!subplan->parallel_safe &&
1012 max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
1013 return true;
1014 save_safe_param_ids = context->safe_param_ids;
1015 context->safe_param_ids = list_concat_copy(context->safe_param_ids,
1016 subplan->paramIds);
1017 if (max_parallel_hazard_walker(subplan->testexpr, context))
1018 return true; /* no need to restore safe_param_ids */
1019 list_free(context->safe_param_ids);
1020 context->safe_param_ids = save_safe_param_ids;
1021 /* we must also check args, but no special Param treatment there */
1022 if (max_parallel_hazard_walker((Node *) subplan->args, context))
1023 return true;
1024 /* don't want to recurse normally, so we're done */
1025 return false;
1026 }
1027
1028 /*
1029 * We can't pass Params to workers at the moment either, so they are also
1030 * parallel-restricted, unless they are PARAM_EXTERN Params or are
1031 * PARAM_EXEC Params listed in safe_param_ids, meaning they could be
1032 * either generated within the worker or can be computed in master and
1033 * then their value can be passed to the worker.
1034 */
1035 else if (IsA(node, Param))
1036 {
1037 Param *param = (Param *) node;
1038
1039 if (param->paramkind == PARAM_EXTERN)
1040 return false;
1041
1042 if (param->paramkind != PARAM_EXEC ||
1043 !list_member_int(context->safe_param_ids, param->paramid))
1044 {
1045 if (max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context))
1046 return true;
1047 }
1048 return false; /* nothing to recurse to */
1049 }
1050
1051 /*
1052 * When we're first invoked on a completely unplanned tree, we must
1053 * recurse into subqueries so to as to locate parallel-unsafe constructs
1054 * anywhere in the tree.
1055 */
1056 else if (IsA(node, Query))
1057 {
1058 Query *query = (Query *) node;
1059
1060 /* SELECT FOR UPDATE/SHARE must be treated as unsafe */
1061 if (query->rowMarks != NULL)
1062 {
1063 context->max_hazard = PROPARALLEL_UNSAFE;
1064 return true;
1065 }
1066
1067 /* Recurse into subselects */
1068 return query_tree_walker(query,
1069 max_parallel_hazard_walker,
1070 context, 0);
1071 }
1072
1073 /* Recurse to check arguments */
1074 return expression_tree_walker(node,
1075 max_parallel_hazard_walker,
1076 context);
1077 }
1078
1079
1080 /*****************************************************************************
1081 * Check clauses for nonstrict functions
1082 *****************************************************************************/
1083
1084 /*
1085 * contain_nonstrict_functions
1086 * Recursively search for nonstrict functions within a clause.
1087 *
1088 * Returns true if any nonstrict construct is found --- ie, anything that
1089 * could produce non-NULL output with a NULL input.
1090 *
1091 * The idea here is that the caller has verified that the expression contains
1092 * one or more Var or Param nodes (as appropriate for the caller's need), and
1093 * now wishes to prove that the expression result will be NULL if any of these
1094 * inputs is NULL. If we return false, then the proof succeeded.
1095 */
1096 bool
contain_nonstrict_functions(Node * clause)1097 contain_nonstrict_functions(Node *clause)
1098 {
1099 return contain_nonstrict_functions_walker(clause, NULL);
1100 }
1101
1102 static bool
contain_nonstrict_functions_checker(Oid func_id,void * context)1103 contain_nonstrict_functions_checker(Oid func_id, void *context)
1104 {
1105 return !func_strict(func_id);
1106 }
1107
1108 static bool
contain_nonstrict_functions_walker(Node * node,void * context)1109 contain_nonstrict_functions_walker(Node *node, void *context)
1110 {
1111 if (node == NULL)
1112 return false;
1113 if (IsA(node, Aggref))
1114 {
1115 /* an aggregate could return non-null with null input */
1116 return true;
1117 }
1118 if (IsA(node, GroupingFunc))
1119 {
1120 /*
1121 * A GroupingFunc doesn't evaluate its arguments, and therefore must
1122 * be treated as nonstrict.
1123 */
1124 return true;
1125 }
1126 if (IsA(node, WindowFunc))
1127 {
1128 /* a window function could return non-null with null input */
1129 return true;
1130 }
1131 if (IsA(node, SubscriptingRef))
1132 {
1133 /*
1134 * subscripting assignment is nonstrict, but subscripting itself is
1135 * strict
1136 */
1137 if (((SubscriptingRef *) node)->refassgnexpr != NULL)
1138 return true;
1139
1140 /* else fall through to check args */
1141 }
1142 if (IsA(node, DistinctExpr))
1143 {
1144 /* IS DISTINCT FROM is inherently non-strict */
1145 return true;
1146 }
1147 if (IsA(node, NullIfExpr))
1148 {
1149 /* NULLIF is inherently non-strict */
1150 return true;
1151 }
1152 if (IsA(node, BoolExpr))
1153 {
1154 BoolExpr *expr = (BoolExpr *) node;
1155
1156 switch (expr->boolop)
1157 {
1158 case AND_EXPR:
1159 case OR_EXPR:
1160 /* AND, OR are inherently non-strict */
1161 return true;
1162 default:
1163 break;
1164 }
1165 }
1166 if (IsA(node, SubLink))
1167 {
1168 /* In some cases a sublink might be strict, but in general not */
1169 return true;
1170 }
1171 if (IsA(node, SubPlan))
1172 return true;
1173 if (IsA(node, AlternativeSubPlan))
1174 return true;
1175 if (IsA(node, FieldStore))
1176 return true;
1177 if (IsA(node, CoerceViaIO))
1178 {
1179 /*
1180 * CoerceViaIO is strict regardless of whether the I/O functions are,
1181 * so just go look at its argument; asking check_functions_in_node is
1182 * useless expense and could deliver the wrong answer.
1183 */
1184 return contain_nonstrict_functions_walker((Node *) ((CoerceViaIO *) node)->arg,
1185 context);
1186 }
1187 if (IsA(node, ArrayCoerceExpr))
1188 {
1189 /*
1190 * ArrayCoerceExpr is strict at the array level, regardless of what
1191 * the per-element expression is; so we should ignore elemexpr and
1192 * recurse only into the arg.
1193 */
1194 return contain_nonstrict_functions_walker((Node *) ((ArrayCoerceExpr *) node)->arg,
1195 context);
1196 }
1197 if (IsA(node, CaseExpr))
1198 return true;
1199 if (IsA(node, ArrayExpr))
1200 return true;
1201 if (IsA(node, RowExpr))
1202 return true;
1203 if (IsA(node, RowCompareExpr))
1204 return true;
1205 if (IsA(node, CoalesceExpr))
1206 return true;
1207 if (IsA(node, MinMaxExpr))
1208 return true;
1209 if (IsA(node, XmlExpr))
1210 return true;
1211 if (IsA(node, NullTest))
1212 return true;
1213 if (IsA(node, BooleanTest))
1214 return true;
1215
1216 /* Check other function-containing nodes */
1217 if (check_functions_in_node(node, contain_nonstrict_functions_checker,
1218 context))
1219 return true;
1220
1221 return expression_tree_walker(node, contain_nonstrict_functions_walker,
1222 context);
1223 }
1224
1225 /*****************************************************************************
1226 * Check clauses for Params
1227 *****************************************************************************/
1228
1229 /*
1230 * contain_exec_param
1231 * Recursively search for PARAM_EXEC Params within a clause.
1232 *
1233 * Returns true if the clause contains any PARAM_EXEC Param with a paramid
1234 * appearing in the given list of Param IDs. Does not descend into
1235 * subqueries!
1236 */
1237 bool
contain_exec_param(Node * clause,List * param_ids)1238 contain_exec_param(Node *clause, List *param_ids)
1239 {
1240 return contain_exec_param_walker(clause, param_ids);
1241 }
1242
1243 static bool
contain_exec_param_walker(Node * node,List * param_ids)1244 contain_exec_param_walker(Node *node, List *param_ids)
1245 {
1246 if (node == NULL)
1247 return false;
1248 if (IsA(node, Param))
1249 {
1250 Param *p = (Param *) node;
1251
1252 if (p->paramkind == PARAM_EXEC &&
1253 list_member_int(param_ids, p->paramid))
1254 return true;
1255 }
1256 return expression_tree_walker(node, contain_exec_param_walker, param_ids);
1257 }
1258
1259 /*****************************************************************************
1260 * Check clauses for context-dependent nodes
1261 *****************************************************************************/
1262
1263 /*
1264 * contain_context_dependent_node
1265 * Recursively search for context-dependent nodes within a clause.
1266 *
1267 * CaseTestExpr nodes must appear directly within the corresponding CaseExpr,
1268 * not nested within another one, or they'll see the wrong test value. If one
1269 * appears "bare" in the arguments of a SQL function, then we can't inline the
1270 * SQL function for fear of creating such a situation. The same applies for
1271 * CaseTestExpr used within the elemexpr of an ArrayCoerceExpr.
1272 *
1273 * CoerceToDomainValue would have the same issue if domain CHECK expressions
1274 * could get inlined into larger expressions, but presently that's impossible.
1275 * Still, it might be allowed in future, or other node types with similar
1276 * issues might get invented. So give this function a generic name, and set
1277 * up the recursion state to allow multiple flag bits.
1278 */
1279 static bool
contain_context_dependent_node(Node * clause)1280 contain_context_dependent_node(Node *clause)
1281 {
1282 int flags = 0;
1283
1284 return contain_context_dependent_node_walker(clause, &flags);
1285 }
1286
1287 #define CCDN_CASETESTEXPR_OK 0x0001 /* CaseTestExpr okay here? */
1288
1289 static bool
contain_context_dependent_node_walker(Node * node,int * flags)1290 contain_context_dependent_node_walker(Node *node, int *flags)
1291 {
1292 if (node == NULL)
1293 return false;
1294 if (IsA(node, CaseTestExpr))
1295 return !(*flags & CCDN_CASETESTEXPR_OK);
1296 else if (IsA(node, CaseExpr))
1297 {
1298 CaseExpr *caseexpr = (CaseExpr *) node;
1299
1300 /*
1301 * If this CASE doesn't have a test expression, then it doesn't create
1302 * a context in which CaseTestExprs should appear, so just fall
1303 * through and treat it as a generic expression node.
1304 */
1305 if (caseexpr->arg)
1306 {
1307 int save_flags = *flags;
1308 bool res;
1309
1310 /*
1311 * Note: in principle, we could distinguish the various sub-parts
1312 * of a CASE construct and set the flag bit only for some of them,
1313 * since we are only expecting CaseTestExprs to appear in the
1314 * "expr" subtree of the CaseWhen nodes. But it doesn't really
1315 * seem worth any extra code. If there are any bare CaseTestExprs
1316 * elsewhere in the CASE, something's wrong already.
1317 */
1318 *flags |= CCDN_CASETESTEXPR_OK;
1319 res = expression_tree_walker(node,
1320 contain_context_dependent_node_walker,
1321 (void *) flags);
1322 *flags = save_flags;
1323 return res;
1324 }
1325 }
1326 else if (IsA(node, ArrayCoerceExpr))
1327 {
1328 ArrayCoerceExpr *ac = (ArrayCoerceExpr *) node;
1329 int save_flags;
1330 bool res;
1331
1332 /* Check the array expression */
1333 if (contain_context_dependent_node_walker((Node *) ac->arg, flags))
1334 return true;
1335
1336 /* Check the elemexpr, which is allowed to contain CaseTestExpr */
1337 save_flags = *flags;
1338 *flags |= CCDN_CASETESTEXPR_OK;
1339 res = contain_context_dependent_node_walker((Node *) ac->elemexpr,
1340 flags);
1341 *flags = save_flags;
1342 return res;
1343 }
1344 return expression_tree_walker(node, contain_context_dependent_node_walker,
1345 (void *) flags);
1346 }
1347
1348 /*****************************************************************************
1349 * Check clauses for Vars passed to non-leakproof functions
1350 *****************************************************************************/
1351
1352 /*
1353 * contain_leaked_vars
1354 * Recursively scan a clause to discover whether it contains any Var
1355 * nodes (of the current query level) that are passed as arguments to
1356 * leaky functions.
1357 *
1358 * Returns true if the clause contains any non-leakproof functions that are
1359 * passed Var nodes of the current query level, and which might therefore leak
1360 * data. Such clauses must be applied after any lower-level security barrier
1361 * clauses.
1362 */
1363 bool
contain_leaked_vars(Node * clause)1364 contain_leaked_vars(Node *clause)
1365 {
1366 return contain_leaked_vars_walker(clause, NULL);
1367 }
1368
1369 static bool
contain_leaked_vars_checker(Oid func_id,void * context)1370 contain_leaked_vars_checker(Oid func_id, void *context)
1371 {
1372 return !get_func_leakproof(func_id);
1373 }
1374
1375 static bool
contain_leaked_vars_walker(Node * node,void * context)1376 contain_leaked_vars_walker(Node *node, void *context)
1377 {
1378 if (node == NULL)
1379 return false;
1380
1381 switch (nodeTag(node))
1382 {
1383 case T_Var:
1384 case T_Const:
1385 case T_Param:
1386 case T_ArrayExpr:
1387 case T_FieldSelect:
1388 case T_FieldStore:
1389 case T_NamedArgExpr:
1390 case T_BoolExpr:
1391 case T_RelabelType:
1392 case T_CollateExpr:
1393 case T_CaseExpr:
1394 case T_CaseTestExpr:
1395 case T_RowExpr:
1396 case T_SQLValueFunction:
1397 case T_NullTest:
1398 case T_BooleanTest:
1399 case T_NextValueExpr:
1400 case T_List:
1401
1402 /*
1403 * We know these node types don't contain function calls; but
1404 * something further down in the node tree might.
1405 */
1406 break;
1407
1408 case T_FuncExpr:
1409 case T_OpExpr:
1410 case T_DistinctExpr:
1411 case T_NullIfExpr:
1412 case T_ScalarArrayOpExpr:
1413 case T_CoerceViaIO:
1414 case T_ArrayCoerceExpr:
1415
1416 /*
1417 * If node contains a leaky function call, and there's any Var
1418 * underneath it, reject.
1419 */
1420 if (check_functions_in_node(node, contain_leaked_vars_checker,
1421 context) &&
1422 contain_var_clause(node))
1423 return true;
1424 break;
1425
1426 case T_SubscriptingRef:
1427 {
1428 SubscriptingRef *sbsref = (SubscriptingRef *) node;
1429
1430 /*
1431 * subscripting assignment is leaky, but subscripted fetches
1432 * are not
1433 */
1434 if (sbsref->refassgnexpr != NULL)
1435 {
1436 /* Node is leaky, so reject if it contains Vars */
1437 if (contain_var_clause(node))
1438 return true;
1439 }
1440 }
1441 break;
1442
1443 case T_RowCompareExpr:
1444 {
1445 /*
1446 * It's worth special-casing this because a leaky comparison
1447 * function only compromises one pair of row elements, which
1448 * might not contain Vars while others do.
1449 */
1450 RowCompareExpr *rcexpr = (RowCompareExpr *) node;
1451 ListCell *opid;
1452 ListCell *larg;
1453 ListCell *rarg;
1454
1455 forthree(opid, rcexpr->opnos,
1456 larg, rcexpr->largs,
1457 rarg, rcexpr->rargs)
1458 {
1459 Oid funcid = get_opcode(lfirst_oid(opid));
1460
1461 if (!get_func_leakproof(funcid) &&
1462 (contain_var_clause((Node *) lfirst(larg)) ||
1463 contain_var_clause((Node *) lfirst(rarg))))
1464 return true;
1465 }
1466 }
1467 break;
1468
1469 case T_MinMaxExpr:
1470 {
1471 /*
1472 * MinMaxExpr is leakproof if the comparison function it calls
1473 * is leakproof.
1474 */
1475 MinMaxExpr *minmaxexpr = (MinMaxExpr *) node;
1476 TypeCacheEntry *typentry;
1477 bool leakproof;
1478
1479 /* Look up the btree comparison function for the datatype */
1480 typentry = lookup_type_cache(minmaxexpr->minmaxtype,
1481 TYPECACHE_CMP_PROC);
1482 if (OidIsValid(typentry->cmp_proc))
1483 leakproof = get_func_leakproof(typentry->cmp_proc);
1484 else
1485 {
1486 /*
1487 * The executor will throw an error, but here we just
1488 * treat the missing function as leaky.
1489 */
1490 leakproof = false;
1491 }
1492
1493 if (!leakproof &&
1494 contain_var_clause((Node *) minmaxexpr->args))
1495 return true;
1496 }
1497 break;
1498
1499 case T_CurrentOfExpr:
1500
1501 /*
1502 * WHERE CURRENT OF doesn't contain leaky function calls.
1503 * Moreover, it is essential that this is considered non-leaky,
1504 * since the planner must always generate a TID scan when CURRENT
1505 * OF is present -- cf. cost_tidscan.
1506 */
1507 return false;
1508
1509 default:
1510
1511 /*
1512 * If we don't recognize the node tag, assume it might be leaky.
1513 * This prevents an unexpected security hole if someone adds a new
1514 * node type that can call a function.
1515 */
1516 return true;
1517 }
1518 return expression_tree_walker(node, contain_leaked_vars_walker,
1519 context);
1520 }
1521
1522 /*
1523 * find_nonnullable_rels
1524 * Determine which base rels are forced nonnullable by given clause.
1525 *
1526 * Returns the set of all Relids that are referenced in the clause in such
1527 * a way that the clause cannot possibly return TRUE if any of these Relids
1528 * is an all-NULL row. (It is OK to err on the side of conservatism; hence
1529 * the analysis here is simplistic.)
1530 *
1531 * The semantics here are subtly different from contain_nonstrict_functions:
1532 * that function is concerned with NULL results from arbitrary expressions,
1533 * but here we assume that the input is a Boolean expression, and wish to
1534 * see if NULL inputs will provably cause a FALSE-or-NULL result. We expect
1535 * the expression to have been AND/OR flattened and converted to implicit-AND
1536 * format.
1537 *
1538 * Note: this function is largely duplicative of find_nonnullable_vars().
1539 * The reason not to simplify this function into a thin wrapper around
1540 * find_nonnullable_vars() is that the tested conditions really are different:
1541 * a clause like "t1.v1 IS NOT NULL OR t1.v2 IS NOT NULL" does not prove
1542 * that either v1 or v2 can't be NULL, but it does prove that the t1 row
1543 * as a whole can't be all-NULL. Also, the behavior for PHVs is different.
1544 *
1545 * top_level is true while scanning top-level AND/OR structure; here, showing
1546 * the result is either FALSE or NULL is good enough. top_level is false when
1547 * we have descended below a NOT or a strict function: now we must be able to
1548 * prove that the subexpression goes to NULL.
1549 *
1550 * We don't use expression_tree_walker here because we don't want to descend
1551 * through very many kinds of nodes; only the ones we can be sure are strict.
1552 */
1553 Relids
find_nonnullable_rels(Node * clause)1554 find_nonnullable_rels(Node *clause)
1555 {
1556 return find_nonnullable_rels_walker(clause, true);
1557 }
1558
1559 static Relids
find_nonnullable_rels_walker(Node * node,bool top_level)1560 find_nonnullable_rels_walker(Node *node, bool top_level)
1561 {
1562 Relids result = NULL;
1563 ListCell *l;
1564
1565 if (node == NULL)
1566 return NULL;
1567 if (IsA(node, Var))
1568 {
1569 Var *var = (Var *) node;
1570
1571 if (var->varlevelsup == 0)
1572 result = bms_make_singleton(var->varno);
1573 }
1574 else if (IsA(node, List))
1575 {
1576 /*
1577 * At top level, we are examining an implicit-AND list: if any of the
1578 * arms produces FALSE-or-NULL then the result is FALSE-or-NULL. If
1579 * not at top level, we are examining the arguments of a strict
1580 * function: if any of them produce NULL then the result of the
1581 * function must be NULL. So in both cases, the set of nonnullable
1582 * rels is the union of those found in the arms, and we pass down the
1583 * top_level flag unmodified.
1584 */
1585 foreach(l, (List *) node)
1586 {
1587 result = bms_join(result,
1588 find_nonnullable_rels_walker(lfirst(l),
1589 top_level));
1590 }
1591 }
1592 else if (IsA(node, FuncExpr))
1593 {
1594 FuncExpr *expr = (FuncExpr *) node;
1595
1596 if (func_strict(expr->funcid))
1597 result = find_nonnullable_rels_walker((Node *) expr->args, false);
1598 }
1599 else if (IsA(node, OpExpr))
1600 {
1601 OpExpr *expr = (OpExpr *) node;
1602
1603 set_opfuncid(expr);
1604 if (func_strict(expr->opfuncid))
1605 result = find_nonnullable_rels_walker((Node *) expr->args, false);
1606 }
1607 else if (IsA(node, ScalarArrayOpExpr))
1608 {
1609 ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
1610
1611 if (is_strict_saop(expr, true))
1612 result = find_nonnullable_rels_walker((Node *) expr->args, false);
1613 }
1614 else if (IsA(node, BoolExpr))
1615 {
1616 BoolExpr *expr = (BoolExpr *) node;
1617
1618 switch (expr->boolop)
1619 {
1620 case AND_EXPR:
1621 /* At top level we can just recurse (to the List case) */
1622 if (top_level)
1623 {
1624 result = find_nonnullable_rels_walker((Node *) expr->args,
1625 top_level);
1626 break;
1627 }
1628
1629 /*
1630 * Below top level, even if one arm produces NULL, the result
1631 * could be FALSE (hence not NULL). However, if *all* the
1632 * arms produce NULL then the result is NULL, so we can take
1633 * the intersection of the sets of nonnullable rels, just as
1634 * for OR. Fall through to share code.
1635 */
1636 /* FALL THRU */
1637 case OR_EXPR:
1638
1639 /*
1640 * OR is strict if all of its arms are, so we can take the
1641 * intersection of the sets of nonnullable rels for each arm.
1642 * This works for both values of top_level.
1643 */
1644 foreach(l, expr->args)
1645 {
1646 Relids subresult;
1647
1648 subresult = find_nonnullable_rels_walker(lfirst(l),
1649 top_level);
1650 if (result == NULL) /* first subresult? */
1651 result = subresult;
1652 else
1653 result = bms_int_members(result, subresult);
1654
1655 /*
1656 * If the intersection is empty, we can stop looking. This
1657 * also justifies the test for first-subresult above.
1658 */
1659 if (bms_is_empty(result))
1660 break;
1661 }
1662 break;
1663 case NOT_EXPR:
1664 /* NOT will return null if its arg is null */
1665 result = find_nonnullable_rels_walker((Node *) expr->args,
1666 false);
1667 break;
1668 default:
1669 elog(ERROR, "unrecognized boolop: %d", (int) expr->boolop);
1670 break;
1671 }
1672 }
1673 else if (IsA(node, RelabelType))
1674 {
1675 RelabelType *expr = (RelabelType *) node;
1676
1677 result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
1678 }
1679 else if (IsA(node, CoerceViaIO))
1680 {
1681 /* not clear this is useful, but it can't hurt */
1682 CoerceViaIO *expr = (CoerceViaIO *) node;
1683
1684 result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
1685 }
1686 else if (IsA(node, ArrayCoerceExpr))
1687 {
1688 /* ArrayCoerceExpr is strict at the array level; ignore elemexpr */
1689 ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
1690
1691 result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
1692 }
1693 else if (IsA(node, ConvertRowtypeExpr))
1694 {
1695 /* not clear this is useful, but it can't hurt */
1696 ConvertRowtypeExpr *expr = (ConvertRowtypeExpr *) node;
1697
1698 result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
1699 }
1700 else if (IsA(node, CollateExpr))
1701 {
1702 CollateExpr *expr = (CollateExpr *) node;
1703
1704 result = find_nonnullable_rels_walker((Node *) expr->arg, top_level);
1705 }
1706 else if (IsA(node, NullTest))
1707 {
1708 /* IS NOT NULL can be considered strict, but only at top level */
1709 NullTest *expr = (NullTest *) node;
1710
1711 if (top_level && expr->nulltesttype == IS_NOT_NULL && !expr->argisrow)
1712 result = find_nonnullable_rels_walker((Node *) expr->arg, false);
1713 }
1714 else if (IsA(node, BooleanTest))
1715 {
1716 /* Boolean tests that reject NULL are strict at top level */
1717 BooleanTest *expr = (BooleanTest *) node;
1718
1719 if (top_level &&
1720 (expr->booltesttype == IS_TRUE ||
1721 expr->booltesttype == IS_FALSE ||
1722 expr->booltesttype == IS_NOT_UNKNOWN))
1723 result = find_nonnullable_rels_walker((Node *) expr->arg, false);
1724 }
1725 else if (IsA(node, PlaceHolderVar))
1726 {
1727 PlaceHolderVar *phv = (PlaceHolderVar *) node;
1728
1729 /*
1730 * If the contained expression forces any rels non-nullable, so does
1731 * the PHV.
1732 */
1733 result = find_nonnullable_rels_walker((Node *) phv->phexpr, top_level);
1734
1735 /*
1736 * If the PHV's syntactic scope is exactly one rel, it will be forced
1737 * to be evaluated at that rel, and so it will behave like a Var of
1738 * that rel: if the rel's entire output goes to null, so will the PHV.
1739 * (If the syntactic scope is a join, we know that the PHV will go to
1740 * null if the whole join does; but that is AND semantics while we
1741 * need OR semantics for find_nonnullable_rels' result, so we can't do
1742 * anything with the knowledge.)
1743 */
1744 if (phv->phlevelsup == 0 &&
1745 bms_membership(phv->phrels) == BMS_SINGLETON)
1746 result = bms_add_members(result, phv->phrels);
1747 }
1748 return result;
1749 }
1750
1751 /*
1752 * find_nonnullable_vars
1753 * Determine which Vars are forced nonnullable by given clause.
1754 *
1755 * Returns a list of all level-zero Vars that are referenced in the clause in
1756 * such a way that the clause cannot possibly return TRUE if any of these Vars
1757 * is NULL. (It is OK to err on the side of conservatism; hence the analysis
1758 * here is simplistic.)
1759 *
1760 * The semantics here are subtly different from contain_nonstrict_functions:
1761 * that function is concerned with NULL results from arbitrary expressions,
1762 * but here we assume that the input is a Boolean expression, and wish to
1763 * see if NULL inputs will provably cause a FALSE-or-NULL result. We expect
1764 * the expression to have been AND/OR flattened and converted to implicit-AND
1765 * format.
1766 *
1767 * The result is a palloc'd List, but we have not copied the member Var nodes.
1768 * Also, we don't bother trying to eliminate duplicate entries.
1769 *
1770 * top_level is true while scanning top-level AND/OR structure; here, showing
1771 * the result is either FALSE or NULL is good enough. top_level is false when
1772 * we have descended below a NOT or a strict function: now we must be able to
1773 * prove that the subexpression goes to NULL.
1774 *
1775 * We don't use expression_tree_walker here because we don't want to descend
1776 * through very many kinds of nodes; only the ones we can be sure are strict.
1777 */
1778 List *
find_nonnullable_vars(Node * clause)1779 find_nonnullable_vars(Node *clause)
1780 {
1781 return find_nonnullable_vars_walker(clause, true);
1782 }
1783
1784 static List *
find_nonnullable_vars_walker(Node * node,bool top_level)1785 find_nonnullable_vars_walker(Node *node, bool top_level)
1786 {
1787 List *result = NIL;
1788 ListCell *l;
1789
1790 if (node == NULL)
1791 return NIL;
1792 if (IsA(node, Var))
1793 {
1794 Var *var = (Var *) node;
1795
1796 if (var->varlevelsup == 0)
1797 result = list_make1(var);
1798 }
1799 else if (IsA(node, List))
1800 {
1801 /*
1802 * At top level, we are examining an implicit-AND list: if any of the
1803 * arms produces FALSE-or-NULL then the result is FALSE-or-NULL. If
1804 * not at top level, we are examining the arguments of a strict
1805 * function: if any of them produce NULL then the result of the
1806 * function must be NULL. So in both cases, the set of nonnullable
1807 * vars is the union of those found in the arms, and we pass down the
1808 * top_level flag unmodified.
1809 */
1810 foreach(l, (List *) node)
1811 {
1812 result = list_concat(result,
1813 find_nonnullable_vars_walker(lfirst(l),
1814 top_level));
1815 }
1816 }
1817 else if (IsA(node, FuncExpr))
1818 {
1819 FuncExpr *expr = (FuncExpr *) node;
1820
1821 if (func_strict(expr->funcid))
1822 result = find_nonnullable_vars_walker((Node *) expr->args, false);
1823 }
1824 else if (IsA(node, OpExpr))
1825 {
1826 OpExpr *expr = (OpExpr *) node;
1827
1828 set_opfuncid(expr);
1829 if (func_strict(expr->opfuncid))
1830 result = find_nonnullable_vars_walker((Node *) expr->args, false);
1831 }
1832 else if (IsA(node, ScalarArrayOpExpr))
1833 {
1834 ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
1835
1836 if (is_strict_saop(expr, true))
1837 result = find_nonnullable_vars_walker((Node *) expr->args, false);
1838 }
1839 else if (IsA(node, BoolExpr))
1840 {
1841 BoolExpr *expr = (BoolExpr *) node;
1842
1843 switch (expr->boolop)
1844 {
1845 case AND_EXPR:
1846 /* At top level we can just recurse (to the List case) */
1847 if (top_level)
1848 {
1849 result = find_nonnullable_vars_walker((Node *) expr->args,
1850 top_level);
1851 break;
1852 }
1853
1854 /*
1855 * Below top level, even if one arm produces NULL, the result
1856 * could be FALSE (hence not NULL). However, if *all* the
1857 * arms produce NULL then the result is NULL, so we can take
1858 * the intersection of the sets of nonnullable vars, just as
1859 * for OR. Fall through to share code.
1860 */
1861 /* FALL THRU */
1862 case OR_EXPR:
1863
1864 /*
1865 * OR is strict if all of its arms are, so we can take the
1866 * intersection of the sets of nonnullable vars for each arm.
1867 * This works for both values of top_level.
1868 */
1869 foreach(l, expr->args)
1870 {
1871 List *subresult;
1872
1873 subresult = find_nonnullable_vars_walker(lfirst(l),
1874 top_level);
1875 if (result == NIL) /* first subresult? */
1876 result = subresult;
1877 else
1878 result = list_intersection(result, subresult);
1879
1880 /*
1881 * If the intersection is empty, we can stop looking. This
1882 * also justifies the test for first-subresult above.
1883 */
1884 if (result == NIL)
1885 break;
1886 }
1887 break;
1888 case NOT_EXPR:
1889 /* NOT will return null if its arg is null */
1890 result = find_nonnullable_vars_walker((Node *) expr->args,
1891 false);
1892 break;
1893 default:
1894 elog(ERROR, "unrecognized boolop: %d", (int) expr->boolop);
1895 break;
1896 }
1897 }
1898 else if (IsA(node, RelabelType))
1899 {
1900 RelabelType *expr = (RelabelType *) node;
1901
1902 result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
1903 }
1904 else if (IsA(node, CoerceViaIO))
1905 {
1906 /* not clear this is useful, but it can't hurt */
1907 CoerceViaIO *expr = (CoerceViaIO *) node;
1908
1909 result = find_nonnullable_vars_walker((Node *) expr->arg, false);
1910 }
1911 else if (IsA(node, ArrayCoerceExpr))
1912 {
1913 /* ArrayCoerceExpr is strict at the array level; ignore elemexpr */
1914 ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
1915
1916 result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
1917 }
1918 else if (IsA(node, ConvertRowtypeExpr))
1919 {
1920 /* not clear this is useful, but it can't hurt */
1921 ConvertRowtypeExpr *expr = (ConvertRowtypeExpr *) node;
1922
1923 result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
1924 }
1925 else if (IsA(node, CollateExpr))
1926 {
1927 CollateExpr *expr = (CollateExpr *) node;
1928
1929 result = find_nonnullable_vars_walker((Node *) expr->arg, top_level);
1930 }
1931 else if (IsA(node, NullTest))
1932 {
1933 /* IS NOT NULL can be considered strict, but only at top level */
1934 NullTest *expr = (NullTest *) node;
1935
1936 if (top_level && expr->nulltesttype == IS_NOT_NULL && !expr->argisrow)
1937 result = find_nonnullable_vars_walker((Node *) expr->arg, false);
1938 }
1939 else if (IsA(node, BooleanTest))
1940 {
1941 /* Boolean tests that reject NULL are strict at top level */
1942 BooleanTest *expr = (BooleanTest *) node;
1943
1944 if (top_level &&
1945 (expr->booltesttype == IS_TRUE ||
1946 expr->booltesttype == IS_FALSE ||
1947 expr->booltesttype == IS_NOT_UNKNOWN))
1948 result = find_nonnullable_vars_walker((Node *) expr->arg, false);
1949 }
1950 else if (IsA(node, PlaceHolderVar))
1951 {
1952 PlaceHolderVar *phv = (PlaceHolderVar *) node;
1953
1954 result = find_nonnullable_vars_walker((Node *) phv->phexpr, top_level);
1955 }
1956 return result;
1957 }
1958
1959 /*
1960 * find_forced_null_vars
1961 * Determine which Vars must be NULL for the given clause to return TRUE.
1962 *
1963 * This is the complement of find_nonnullable_vars: find the level-zero Vars
1964 * that must be NULL for the clause to return TRUE. (It is OK to err on the
1965 * side of conservatism; hence the analysis here is simplistic. In fact,
1966 * we only detect simple "var IS NULL" tests at the top level.)
1967 *
1968 * The result is a palloc'd List, but we have not copied the member Var nodes.
1969 * Also, we don't bother trying to eliminate duplicate entries.
1970 */
1971 List *
find_forced_null_vars(Node * node)1972 find_forced_null_vars(Node *node)
1973 {
1974 List *result = NIL;
1975 Var *var;
1976 ListCell *l;
1977
1978 if (node == NULL)
1979 return NIL;
1980 /* Check single-clause cases using subroutine */
1981 var = find_forced_null_var(node);
1982 if (var)
1983 {
1984 result = list_make1(var);
1985 }
1986 /* Otherwise, handle AND-conditions */
1987 else if (IsA(node, List))
1988 {
1989 /*
1990 * At top level, we are examining an implicit-AND list: if any of the
1991 * arms produces FALSE-or-NULL then the result is FALSE-or-NULL.
1992 */
1993 foreach(l, (List *) node)
1994 {
1995 result = list_concat(result,
1996 find_forced_null_vars(lfirst(l)));
1997 }
1998 }
1999 else if (IsA(node, BoolExpr))
2000 {
2001 BoolExpr *expr = (BoolExpr *) node;
2002
2003 /*
2004 * We don't bother considering the OR case, because it's fairly
2005 * unlikely anyone would write "v1 IS NULL OR v1 IS NULL". Likewise,
2006 * the NOT case isn't worth expending code on.
2007 */
2008 if (expr->boolop == AND_EXPR)
2009 {
2010 /* At top level we can just recurse (to the List case) */
2011 result = find_forced_null_vars((Node *) expr->args);
2012 }
2013 }
2014 return result;
2015 }
2016
2017 /*
2018 * find_forced_null_var
2019 * Return the Var forced null by the given clause, or NULL if it's
2020 * not an IS NULL-type clause. For success, the clause must enforce
2021 * *only* nullness of the particular Var, not any other conditions.
2022 *
2023 * This is just the single-clause case of find_forced_null_vars(), without
2024 * any allowance for AND conditions. It's used by initsplan.c on individual
2025 * qual clauses. The reason for not just applying find_forced_null_vars()
2026 * is that if an AND of an IS NULL clause with something else were to somehow
2027 * survive AND/OR flattening, initsplan.c might get fooled into discarding
2028 * the whole clause when only the IS NULL part of it had been proved redundant.
2029 */
2030 Var *
find_forced_null_var(Node * node)2031 find_forced_null_var(Node *node)
2032 {
2033 if (node == NULL)
2034 return NULL;
2035 if (IsA(node, NullTest))
2036 {
2037 /* check for var IS NULL */
2038 NullTest *expr = (NullTest *) node;
2039
2040 if (expr->nulltesttype == IS_NULL && !expr->argisrow)
2041 {
2042 Var *var = (Var *) expr->arg;
2043
2044 if (var && IsA(var, Var) &&
2045 var->varlevelsup == 0)
2046 return var;
2047 }
2048 }
2049 else if (IsA(node, BooleanTest))
2050 {
2051 /* var IS UNKNOWN is equivalent to var IS NULL */
2052 BooleanTest *expr = (BooleanTest *) node;
2053
2054 if (expr->booltesttype == IS_UNKNOWN)
2055 {
2056 Var *var = (Var *) expr->arg;
2057
2058 if (var && IsA(var, Var) &&
2059 var->varlevelsup == 0)
2060 return var;
2061 }
2062 }
2063 return NULL;
2064 }
2065
2066 /*
2067 * Can we treat a ScalarArrayOpExpr as strict?
2068 *
2069 * If "falseOK" is true, then a "false" result can be considered strict,
2070 * else we need to guarantee an actual NULL result for NULL input.
2071 *
2072 * "foo op ALL array" is strict if the op is strict *and* we can prove
2073 * that the array input isn't an empty array. We can check that
2074 * for the cases of an array constant and an ARRAY[] construct.
2075 *
2076 * "foo op ANY array" is strict in the falseOK sense if the op is strict.
2077 * If not falseOK, the test is the same as for "foo op ALL array".
2078 */
2079 static bool
is_strict_saop(ScalarArrayOpExpr * expr,bool falseOK)2080 is_strict_saop(ScalarArrayOpExpr *expr, bool falseOK)
2081 {
2082 Node *rightop;
2083
2084 /* The contained operator must be strict. */
2085 set_sa_opfuncid(expr);
2086 if (!func_strict(expr->opfuncid))
2087 return false;
2088 /* If ANY and falseOK, that's all we need to check. */
2089 if (expr->useOr && falseOK)
2090 return true;
2091 /* Else, we have to see if the array is provably non-empty. */
2092 Assert(list_length(expr->args) == 2);
2093 rightop = (Node *) lsecond(expr->args);
2094 if (rightop && IsA(rightop, Const))
2095 {
2096 Datum arraydatum = ((Const *) rightop)->constvalue;
2097 bool arrayisnull = ((Const *) rightop)->constisnull;
2098 ArrayType *arrayval;
2099 int nitems;
2100
2101 if (arrayisnull)
2102 return false;
2103 arrayval = DatumGetArrayTypeP(arraydatum);
2104 nitems = ArrayGetNItems(ARR_NDIM(arrayval), ARR_DIMS(arrayval));
2105 if (nitems > 0)
2106 return true;
2107 }
2108 else if (rightop && IsA(rightop, ArrayExpr))
2109 {
2110 ArrayExpr *arrayexpr = (ArrayExpr *) rightop;
2111
2112 if (arrayexpr->elements != NIL && !arrayexpr->multidims)
2113 return true;
2114 }
2115 return false;
2116 }
2117
2118
2119 /*****************************************************************************
2120 * Check for "pseudo-constant" clauses
2121 *****************************************************************************/
2122
2123 /*
2124 * is_pseudo_constant_clause
2125 * Detect whether an expression is "pseudo constant", ie, it contains no
2126 * variables of the current query level and no uses of volatile functions.
2127 * Such an expr is not necessarily a true constant: it can still contain
2128 * Params and outer-level Vars, not to mention functions whose results
2129 * may vary from one statement to the next. However, the expr's value
2130 * will be constant over any one scan of the current query, so it can be
2131 * used as, eg, an indexscan key. (Actually, the condition for indexscan
2132 * keys is weaker than this; see is_pseudo_constant_for_index().)
2133 *
2134 * CAUTION: this function omits to test for one very important class of
2135 * not-constant expressions, namely aggregates (Aggrefs). In current usage
2136 * this is only applied to WHERE clauses and so a check for Aggrefs would be
2137 * a waste of cycles; but be sure to also check contain_agg_clause() if you
2138 * want to know about pseudo-constness in other contexts. The same goes
2139 * for window functions (WindowFuncs).
2140 */
2141 bool
is_pseudo_constant_clause(Node * clause)2142 is_pseudo_constant_clause(Node *clause)
2143 {
2144 /*
2145 * We could implement this check in one recursive scan. But since the
2146 * check for volatile functions is both moderately expensive and unlikely
2147 * to fail, it seems better to look for Vars first and only check for
2148 * volatile functions if we find no Vars.
2149 */
2150 if (!contain_var_clause(clause) &&
2151 !contain_volatile_functions(clause))
2152 return true;
2153 return false;
2154 }
2155
2156 /*
2157 * is_pseudo_constant_clause_relids
2158 * Same as above, except caller already has available the var membership
2159 * of the expression; this lets us avoid the contain_var_clause() scan.
2160 */
2161 bool
is_pseudo_constant_clause_relids(Node * clause,Relids relids)2162 is_pseudo_constant_clause_relids(Node *clause, Relids relids)
2163 {
2164 if (bms_is_empty(relids) &&
2165 !contain_volatile_functions(clause))
2166 return true;
2167 return false;
2168 }
2169
2170
2171 /*****************************************************************************
2172 * *
2173 * General clause-manipulating routines *
2174 * *
2175 *****************************************************************************/
2176
2177 /*
2178 * NumRelids
2179 * (formerly clause_relids)
2180 *
2181 * Returns the number of different relations referenced in 'clause'.
2182 */
2183 int
NumRelids(Node * clause)2184 NumRelids(Node *clause)
2185 {
2186 return NumRelids_new(NULL, clause);
2187 }
2188
2189 int
NumRelids_new(PlannerInfo * root,Node * clause)2190 NumRelids_new(PlannerInfo *root, Node *clause)
2191 {
2192 Relids varnos = pull_varnos(root, clause);
2193 int result = bms_num_members(varnos);
2194
2195 bms_free(varnos);
2196 return result;
2197 }
2198
2199 /*
2200 * CommuteOpExpr: commute a binary operator clause
2201 *
2202 * XXX the clause is destructively modified!
2203 */
2204 void
CommuteOpExpr(OpExpr * clause)2205 CommuteOpExpr(OpExpr *clause)
2206 {
2207 Oid opoid;
2208 Node *temp;
2209
2210 /* Sanity checks: caller is at fault if these fail */
2211 if (!is_opclause(clause) ||
2212 list_length(clause->args) != 2)
2213 elog(ERROR, "cannot commute non-binary-operator clause");
2214
2215 opoid = get_commutator(clause->opno);
2216
2217 if (!OidIsValid(opoid))
2218 elog(ERROR, "could not find commutator for operator %u",
2219 clause->opno);
2220
2221 /*
2222 * modify the clause in-place!
2223 */
2224 clause->opno = opoid;
2225 clause->opfuncid = InvalidOid;
2226 /* opresulttype, opretset, opcollid, inputcollid need not change */
2227
2228 temp = linitial(clause->args);
2229 linitial(clause->args) = lsecond(clause->args);
2230 lsecond(clause->args) = temp;
2231 }
2232
2233 /*
2234 * Helper for eval_const_expressions: check that datatype of an attribute
2235 * is still what it was when the expression was parsed. This is needed to
2236 * guard against improper simplification after ALTER COLUMN TYPE. (XXX we
2237 * may well need to make similar checks elsewhere?)
2238 *
2239 * rowtypeid may come from a whole-row Var, and therefore it can be a domain
2240 * over composite, but for this purpose we only care about checking the type
2241 * of a contained field.
2242 */
2243 static bool
rowtype_field_matches(Oid rowtypeid,int fieldnum,Oid expectedtype,int32 expectedtypmod,Oid expectedcollation)2244 rowtype_field_matches(Oid rowtypeid, int fieldnum,
2245 Oid expectedtype, int32 expectedtypmod,
2246 Oid expectedcollation)
2247 {
2248 TupleDesc tupdesc;
2249 Form_pg_attribute attr;
2250
2251 /* No issue for RECORD, since there is no way to ALTER such a type */
2252 if (rowtypeid == RECORDOID)
2253 return true;
2254 tupdesc = lookup_rowtype_tupdesc_domain(rowtypeid, -1, false);
2255 if (fieldnum <= 0 || fieldnum > tupdesc->natts)
2256 {
2257 ReleaseTupleDesc(tupdesc);
2258 return false;
2259 }
2260 attr = TupleDescAttr(tupdesc, fieldnum - 1);
2261 if (attr->attisdropped ||
2262 attr->atttypid != expectedtype ||
2263 attr->atttypmod != expectedtypmod ||
2264 attr->attcollation != expectedcollation)
2265 {
2266 ReleaseTupleDesc(tupdesc);
2267 return false;
2268 }
2269 ReleaseTupleDesc(tupdesc);
2270 return true;
2271 }
2272
2273
2274 /*--------------------
2275 * eval_const_expressions
2276 *
2277 * Reduce any recognizably constant subexpressions of the given
2278 * expression tree, for example "2 + 2" => "4". More interestingly,
2279 * we can reduce certain boolean expressions even when they contain
2280 * non-constant subexpressions: "x OR true" => "true" no matter what
2281 * the subexpression x is. (XXX We assume that no such subexpression
2282 * will have important side-effects, which is not necessarily a good
2283 * assumption in the presence of user-defined functions; do we need a
2284 * pg_proc flag that prevents discarding the execution of a function?)
2285 *
2286 * We do understand that certain functions may deliver non-constant
2287 * results even with constant inputs, "nextval()" being the classic
2288 * example. Functions that are not marked "immutable" in pg_proc
2289 * will not be pre-evaluated here, although we will reduce their
2290 * arguments as far as possible.
2291 *
2292 * Whenever a function is eliminated from the expression by means of
2293 * constant-expression evaluation or inlining, we add the function to
2294 * root->glob->invalItems. This ensures the plan is known to depend on
2295 * such functions, even though they aren't referenced anymore.
2296 *
2297 * We assume that the tree has already been type-checked and contains
2298 * only operators and functions that are reasonable to try to execute.
2299 *
2300 * NOTE: "root" can be passed as NULL if the caller never wants to do any
2301 * Param substitutions nor receive info about inlined functions.
2302 *
2303 * NOTE: the planner assumes that this will always flatten nested AND and
2304 * OR clauses into N-argument form. See comments in prepqual.c.
2305 *
2306 * NOTE: another critical effect is that any function calls that require
2307 * default arguments will be expanded, and named-argument calls will be
2308 * converted to positional notation. The executor won't handle either.
2309 *--------------------
2310 */
2311 Node *
eval_const_expressions(PlannerInfo * root,Node * node)2312 eval_const_expressions(PlannerInfo *root, Node *node)
2313 {
2314 eval_const_expressions_context context;
2315
2316 if (root)
2317 context.boundParams = root->glob->boundParams; /* bound Params */
2318 else
2319 context.boundParams = NULL;
2320 context.root = root; /* for inlined-function dependencies */
2321 context.active_fns = NIL; /* nothing being recursively simplified */
2322 context.case_val = NULL; /* no CASE being examined */
2323 context.estimate = false; /* safe transformations only */
2324 return eval_const_expressions_mutator(node, &context);
2325 }
2326
2327 /*--------------------
2328 * estimate_expression_value
2329 *
2330 * This function attempts to estimate the value of an expression for
2331 * planning purposes. It is in essence a more aggressive version of
2332 * eval_const_expressions(): we will perform constant reductions that are
2333 * not necessarily 100% safe, but are reasonable for estimation purposes.
2334 *
2335 * Currently the extra steps that are taken in this mode are:
2336 * 1. Substitute values for Params, where a bound Param value has been made
2337 * available by the caller of planner(), even if the Param isn't marked
2338 * constant. This effectively means that we plan using the first supplied
2339 * value of the Param.
2340 * 2. Fold stable, as well as immutable, functions to constants.
2341 * 3. Reduce PlaceHolderVar nodes to their contained expressions.
2342 *--------------------
2343 */
2344 Node *
estimate_expression_value(PlannerInfo * root,Node * node)2345 estimate_expression_value(PlannerInfo *root, Node *node)
2346 {
2347 eval_const_expressions_context context;
2348
2349 context.boundParams = root->glob->boundParams; /* bound Params */
2350 /* we do not need to mark the plan as depending on inlined functions */
2351 context.root = NULL;
2352 context.active_fns = NIL; /* nothing being recursively simplified */
2353 context.case_val = NULL; /* no CASE being examined */
2354 context.estimate = true; /* unsafe transformations OK */
2355 return eval_const_expressions_mutator(node, &context);
2356 }
2357
2358 /*
2359 * The generic case in eval_const_expressions_mutator is to recurse using
2360 * expression_tree_mutator, which will copy the given node unchanged but
2361 * const-simplify its arguments (if any) as far as possible. If the node
2362 * itself does immutable processing, and each of its arguments were reduced
2363 * to a Const, we can then reduce it to a Const using evaluate_expr. (Some
2364 * node types need more complicated logic; for example, a CASE expression
2365 * might be reducible to a constant even if not all its subtrees are.)
2366 */
2367 #define ece_generic_processing(node) \
2368 expression_tree_mutator((Node *) (node), eval_const_expressions_mutator, \
2369 (void *) context)
2370
2371 /*
2372 * Check whether all arguments of the given node were reduced to Consts.
2373 * By going directly to expression_tree_walker, contain_non_const_walker
2374 * is not applied to the node itself, only to its children.
2375 */
2376 #define ece_all_arguments_const(node) \
2377 (!expression_tree_walker((Node *) (node), contain_non_const_walker, NULL))
2378
2379 /* Generic macro for applying evaluate_expr */
2380 #define ece_evaluate_expr(node) \
2381 ((Node *) evaluate_expr((Expr *) (node), \
2382 exprType((Node *) (node)), \
2383 exprTypmod((Node *) (node)), \
2384 exprCollation((Node *) (node))))
2385
2386 /*
2387 * Recursive guts of eval_const_expressions/estimate_expression_value
2388 */
2389 static Node *
eval_const_expressions_mutator(Node * node,eval_const_expressions_context * context)2390 eval_const_expressions_mutator(Node *node,
2391 eval_const_expressions_context *context)
2392 {
2393 if (node == NULL)
2394 return NULL;
2395 switch (nodeTag(node))
2396 {
2397 case T_Param:
2398 {
2399 Param *param = (Param *) node;
2400 ParamListInfo paramLI = context->boundParams;
2401
2402 /* Look to see if we've been given a value for this Param */
2403 if (param->paramkind == PARAM_EXTERN &&
2404 paramLI != NULL &&
2405 param->paramid > 0 &&
2406 param->paramid <= paramLI->numParams)
2407 {
2408 ParamExternData *prm;
2409 ParamExternData prmdata;
2410
2411 /*
2412 * Give hook a chance in case parameter is dynamic. Tell
2413 * it that this fetch is speculative, so it should avoid
2414 * erroring out if parameter is unavailable.
2415 */
2416 if (paramLI->paramFetch != NULL)
2417 prm = paramLI->paramFetch(paramLI, param->paramid,
2418 true, &prmdata);
2419 else
2420 prm = ¶mLI->params[param->paramid - 1];
2421
2422 /*
2423 * We don't just check OidIsValid, but insist that the
2424 * fetched type match the Param, just in case the hook did
2425 * something unexpected. No need to throw an error here
2426 * though; leave that for runtime.
2427 */
2428 if (OidIsValid(prm->ptype) &&
2429 prm->ptype == param->paramtype)
2430 {
2431 /* OK to substitute parameter value? */
2432 if (context->estimate ||
2433 (prm->pflags & PARAM_FLAG_CONST))
2434 {
2435 /*
2436 * Return a Const representing the param value.
2437 * Must copy pass-by-ref datatypes, since the
2438 * Param might be in a memory context
2439 * shorter-lived than our output plan should be.
2440 */
2441 int16 typLen;
2442 bool typByVal;
2443 Datum pval;
2444
2445 get_typlenbyval(param->paramtype,
2446 &typLen, &typByVal);
2447 if (prm->isnull || typByVal)
2448 pval = prm->value;
2449 else
2450 pval = datumCopy(prm->value, typByVal, typLen);
2451 return (Node *) makeConst(param->paramtype,
2452 param->paramtypmod,
2453 param->paramcollid,
2454 (int) typLen,
2455 pval,
2456 prm->isnull,
2457 typByVal);
2458 }
2459 }
2460 }
2461
2462 /*
2463 * Not replaceable, so just copy the Param (no need to
2464 * recurse)
2465 */
2466 return (Node *) copyObject(param);
2467 }
2468 case T_WindowFunc:
2469 {
2470 WindowFunc *expr = (WindowFunc *) node;
2471 Oid funcid = expr->winfnoid;
2472 List *args;
2473 Expr *aggfilter;
2474 HeapTuple func_tuple;
2475 WindowFunc *newexpr;
2476
2477 /*
2478 * We can't really simplify a WindowFunc node, but we mustn't
2479 * just fall through to the default processing, because we
2480 * have to apply expand_function_arguments to its argument
2481 * list. That takes care of inserting default arguments and
2482 * expanding named-argument notation.
2483 */
2484 func_tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
2485 if (!HeapTupleIsValid(func_tuple))
2486 elog(ERROR, "cache lookup failed for function %u", funcid);
2487
2488 args = expand_function_arguments(expr->args, expr->wintype,
2489 func_tuple);
2490
2491 ReleaseSysCache(func_tuple);
2492
2493 /* Now, recursively simplify the args (which are a List) */
2494 args = (List *)
2495 expression_tree_mutator((Node *) args,
2496 eval_const_expressions_mutator,
2497 (void *) context);
2498 /* ... and the filter expression, which isn't */
2499 aggfilter = (Expr *)
2500 eval_const_expressions_mutator((Node *) expr->aggfilter,
2501 context);
2502
2503 /* And build the replacement WindowFunc node */
2504 newexpr = makeNode(WindowFunc);
2505 newexpr->winfnoid = expr->winfnoid;
2506 newexpr->wintype = expr->wintype;
2507 newexpr->wincollid = expr->wincollid;
2508 newexpr->inputcollid = expr->inputcollid;
2509 newexpr->args = args;
2510 newexpr->aggfilter = aggfilter;
2511 newexpr->winref = expr->winref;
2512 newexpr->winstar = expr->winstar;
2513 newexpr->winagg = expr->winagg;
2514 newexpr->location = expr->location;
2515
2516 return (Node *) newexpr;
2517 }
2518 case T_FuncExpr:
2519 {
2520 FuncExpr *expr = (FuncExpr *) node;
2521 List *args = expr->args;
2522 Expr *simple;
2523 FuncExpr *newexpr;
2524
2525 /*
2526 * Code for op/func reduction is pretty bulky, so split it out
2527 * as a separate function. Note: exprTypmod normally returns
2528 * -1 for a FuncExpr, but not when the node is recognizably a
2529 * length coercion; we want to preserve the typmod in the
2530 * eventual Const if so.
2531 */
2532 simple = simplify_function(expr->funcid,
2533 expr->funcresulttype,
2534 exprTypmod(node),
2535 expr->funccollid,
2536 expr->inputcollid,
2537 &args,
2538 expr->funcvariadic,
2539 true,
2540 true,
2541 context);
2542 if (simple) /* successfully simplified it */
2543 return (Node *) simple;
2544
2545 /*
2546 * The expression cannot be simplified any further, so build
2547 * and return a replacement FuncExpr node using the
2548 * possibly-simplified arguments. Note that we have also
2549 * converted the argument list to positional notation.
2550 */
2551 newexpr = makeNode(FuncExpr);
2552 newexpr->funcid = expr->funcid;
2553 newexpr->funcresulttype = expr->funcresulttype;
2554 newexpr->funcretset = expr->funcretset;
2555 newexpr->funcvariadic = expr->funcvariadic;
2556 newexpr->funcformat = expr->funcformat;
2557 newexpr->funccollid = expr->funccollid;
2558 newexpr->inputcollid = expr->inputcollid;
2559 newexpr->args = args;
2560 newexpr->location = expr->location;
2561 return (Node *) newexpr;
2562 }
2563 case T_OpExpr:
2564 {
2565 OpExpr *expr = (OpExpr *) node;
2566 List *args = expr->args;
2567 Expr *simple;
2568 OpExpr *newexpr;
2569
2570 /*
2571 * Need to get OID of underlying function. Okay to scribble
2572 * on input to this extent.
2573 */
2574 set_opfuncid(expr);
2575
2576 /*
2577 * Code for op/func reduction is pretty bulky, so split it out
2578 * as a separate function.
2579 */
2580 simple = simplify_function(expr->opfuncid,
2581 expr->opresulttype, -1,
2582 expr->opcollid,
2583 expr->inputcollid,
2584 &args,
2585 false,
2586 true,
2587 true,
2588 context);
2589 if (simple) /* successfully simplified it */
2590 return (Node *) simple;
2591
2592 /*
2593 * If the operator is boolean equality or inequality, we know
2594 * how to simplify cases involving one constant and one
2595 * non-constant argument.
2596 */
2597 if (expr->opno == BooleanEqualOperator ||
2598 expr->opno == BooleanNotEqualOperator)
2599 {
2600 simple = (Expr *) simplify_boolean_equality(expr->opno,
2601 args);
2602 if (simple) /* successfully simplified it */
2603 return (Node *) simple;
2604 }
2605
2606 /*
2607 * The expression cannot be simplified any further, so build
2608 * and return a replacement OpExpr node using the
2609 * possibly-simplified arguments.
2610 */
2611 newexpr = makeNode(OpExpr);
2612 newexpr->opno = expr->opno;
2613 newexpr->opfuncid = expr->opfuncid;
2614 newexpr->opresulttype = expr->opresulttype;
2615 newexpr->opretset = expr->opretset;
2616 newexpr->opcollid = expr->opcollid;
2617 newexpr->inputcollid = expr->inputcollid;
2618 newexpr->args = args;
2619 newexpr->location = expr->location;
2620 return (Node *) newexpr;
2621 }
2622 case T_DistinctExpr:
2623 {
2624 DistinctExpr *expr = (DistinctExpr *) node;
2625 List *args;
2626 ListCell *arg;
2627 bool has_null_input = false;
2628 bool all_null_input = true;
2629 bool has_nonconst_input = false;
2630 Expr *simple;
2631 DistinctExpr *newexpr;
2632
2633 /*
2634 * Reduce constants in the DistinctExpr's arguments. We know
2635 * args is either NIL or a List node, so we can call
2636 * expression_tree_mutator directly rather than recursing to
2637 * self.
2638 */
2639 args = (List *) expression_tree_mutator((Node *) expr->args,
2640 eval_const_expressions_mutator,
2641 (void *) context);
2642
2643 /*
2644 * We must do our own check for NULLs because DistinctExpr has
2645 * different results for NULL input than the underlying
2646 * operator does.
2647 */
2648 foreach(arg, args)
2649 {
2650 if (IsA(lfirst(arg), Const))
2651 {
2652 has_null_input |= ((Const *) lfirst(arg))->constisnull;
2653 all_null_input &= ((Const *) lfirst(arg))->constisnull;
2654 }
2655 else
2656 has_nonconst_input = true;
2657 }
2658
2659 /* all constants? then can optimize this out */
2660 if (!has_nonconst_input)
2661 {
2662 /* all nulls? then not distinct */
2663 if (all_null_input)
2664 return makeBoolConst(false, false);
2665
2666 /* one null? then distinct */
2667 if (has_null_input)
2668 return makeBoolConst(true, false);
2669
2670 /* otherwise try to evaluate the '=' operator */
2671 /* (NOT okay to try to inline it, though!) */
2672
2673 /*
2674 * Need to get OID of underlying function. Okay to
2675 * scribble on input to this extent.
2676 */
2677 set_opfuncid((OpExpr *) expr); /* rely on struct
2678 * equivalence */
2679
2680 /*
2681 * Code for op/func reduction is pretty bulky, so split it
2682 * out as a separate function.
2683 */
2684 simple = simplify_function(expr->opfuncid,
2685 expr->opresulttype, -1,
2686 expr->opcollid,
2687 expr->inputcollid,
2688 &args,
2689 false,
2690 false,
2691 false,
2692 context);
2693 if (simple) /* successfully simplified it */
2694 {
2695 /*
2696 * Since the underlying operator is "=", must negate
2697 * its result
2698 */
2699 Const *csimple = castNode(Const, simple);
2700
2701 csimple->constvalue =
2702 BoolGetDatum(!DatumGetBool(csimple->constvalue));
2703 return (Node *) csimple;
2704 }
2705 }
2706
2707 /*
2708 * The expression cannot be simplified any further, so build
2709 * and return a replacement DistinctExpr node using the
2710 * possibly-simplified arguments.
2711 */
2712 newexpr = makeNode(DistinctExpr);
2713 newexpr->opno = expr->opno;
2714 newexpr->opfuncid = expr->opfuncid;
2715 newexpr->opresulttype = expr->opresulttype;
2716 newexpr->opretset = expr->opretset;
2717 newexpr->opcollid = expr->opcollid;
2718 newexpr->inputcollid = expr->inputcollid;
2719 newexpr->args = args;
2720 newexpr->location = expr->location;
2721 return (Node *) newexpr;
2722 }
2723 case T_ScalarArrayOpExpr:
2724 {
2725 ScalarArrayOpExpr *saop;
2726
2727 /* Copy the node and const-simplify its arguments */
2728 saop = (ScalarArrayOpExpr *) ece_generic_processing(node);
2729
2730 /* Make sure we know underlying function */
2731 set_sa_opfuncid(saop);
2732
2733 /*
2734 * If all arguments are Consts, and it's a safe function, we
2735 * can fold to a constant
2736 */
2737 if (ece_all_arguments_const(saop) &&
2738 ece_function_is_safe(saop->opfuncid, context))
2739 return ece_evaluate_expr(saop);
2740 return (Node *) saop;
2741 }
2742 case T_BoolExpr:
2743 {
2744 BoolExpr *expr = (BoolExpr *) node;
2745
2746 switch (expr->boolop)
2747 {
2748 case OR_EXPR:
2749 {
2750 List *newargs;
2751 bool haveNull = false;
2752 bool forceTrue = false;
2753
2754 newargs = simplify_or_arguments(expr->args,
2755 context,
2756 &haveNull,
2757 &forceTrue);
2758 if (forceTrue)
2759 return makeBoolConst(true, false);
2760 if (haveNull)
2761 newargs = lappend(newargs,
2762 makeBoolConst(false, true));
2763 /* If all the inputs are FALSE, result is FALSE */
2764 if (newargs == NIL)
2765 return makeBoolConst(false, false);
2766
2767 /*
2768 * If only one nonconst-or-NULL input, it's the
2769 * result
2770 */
2771 if (list_length(newargs) == 1)
2772 return (Node *) linitial(newargs);
2773 /* Else we still need an OR node */
2774 return (Node *) make_orclause(newargs);
2775 }
2776 case AND_EXPR:
2777 {
2778 List *newargs;
2779 bool haveNull = false;
2780 bool forceFalse = false;
2781
2782 newargs = simplify_and_arguments(expr->args,
2783 context,
2784 &haveNull,
2785 &forceFalse);
2786 if (forceFalse)
2787 return makeBoolConst(false, false);
2788 if (haveNull)
2789 newargs = lappend(newargs,
2790 makeBoolConst(false, true));
2791 /* If all the inputs are TRUE, result is TRUE */
2792 if (newargs == NIL)
2793 return makeBoolConst(true, false);
2794
2795 /*
2796 * If only one nonconst-or-NULL input, it's the
2797 * result
2798 */
2799 if (list_length(newargs) == 1)
2800 return (Node *) linitial(newargs);
2801 /* Else we still need an AND node */
2802 return (Node *) make_andclause(newargs);
2803 }
2804 case NOT_EXPR:
2805 {
2806 Node *arg;
2807
2808 Assert(list_length(expr->args) == 1);
2809 arg = eval_const_expressions_mutator(linitial(expr->args),
2810 context);
2811
2812 /*
2813 * Use negate_clause() to see if we can simplify
2814 * away the NOT.
2815 */
2816 return negate_clause(arg);
2817 }
2818 default:
2819 elog(ERROR, "unrecognized boolop: %d",
2820 (int) expr->boolop);
2821 break;
2822 }
2823 break;
2824 }
2825 case T_SubPlan:
2826 case T_AlternativeSubPlan:
2827
2828 /*
2829 * Return a SubPlan unchanged --- too late to do anything with it.
2830 *
2831 * XXX should we ereport() here instead? Probably this routine
2832 * should never be invoked after SubPlan creation.
2833 */
2834 return node;
2835 case T_RelabelType:
2836 {
2837 RelabelType *relabel = (RelabelType *) node;
2838 Node *arg;
2839
2840 /* Simplify the input ... */
2841 arg = eval_const_expressions_mutator((Node *) relabel->arg,
2842 context);
2843 /* ... and attach a new RelabelType node, if needed */
2844 return applyRelabelType(arg,
2845 relabel->resulttype,
2846 relabel->resulttypmod,
2847 relabel->resultcollid,
2848 relabel->relabelformat,
2849 relabel->location,
2850 true);
2851 }
2852 case T_CoerceViaIO:
2853 {
2854 CoerceViaIO *expr = (CoerceViaIO *) node;
2855 List *args;
2856 Oid outfunc;
2857 bool outtypisvarlena;
2858 Oid infunc;
2859 Oid intypioparam;
2860 Expr *simple;
2861 CoerceViaIO *newexpr;
2862
2863 /* Make a List so we can use simplify_function */
2864 args = list_make1(expr->arg);
2865
2866 /*
2867 * CoerceViaIO represents calling the source type's output
2868 * function then the result type's input function. So, try to
2869 * simplify it as though it were a stack of two such function
2870 * calls. First we need to know what the functions are.
2871 *
2872 * Note that the coercion functions are assumed not to care
2873 * about input collation, so we just pass InvalidOid for that.
2874 */
2875 getTypeOutputInfo(exprType((Node *) expr->arg),
2876 &outfunc, &outtypisvarlena);
2877 getTypeInputInfo(expr->resulttype,
2878 &infunc, &intypioparam);
2879
2880 simple = simplify_function(outfunc,
2881 CSTRINGOID, -1,
2882 InvalidOid,
2883 InvalidOid,
2884 &args,
2885 false,
2886 true,
2887 true,
2888 context);
2889 if (simple) /* successfully simplified output fn */
2890 {
2891 /*
2892 * Input functions may want 1 to 3 arguments. We always
2893 * supply all three, trusting that nothing downstream will
2894 * complain.
2895 */
2896 args = list_make3(simple,
2897 makeConst(OIDOID,
2898 -1,
2899 InvalidOid,
2900 sizeof(Oid),
2901 ObjectIdGetDatum(intypioparam),
2902 false,
2903 true),
2904 makeConst(INT4OID,
2905 -1,
2906 InvalidOid,
2907 sizeof(int32),
2908 Int32GetDatum(-1),
2909 false,
2910 true));
2911
2912 simple = simplify_function(infunc,
2913 expr->resulttype, -1,
2914 expr->resultcollid,
2915 InvalidOid,
2916 &args,
2917 false,
2918 false,
2919 true,
2920 context);
2921 if (simple) /* successfully simplified input fn */
2922 return (Node *) simple;
2923 }
2924
2925 /*
2926 * The expression cannot be simplified any further, so build
2927 * and return a replacement CoerceViaIO node using the
2928 * possibly-simplified argument.
2929 */
2930 newexpr = makeNode(CoerceViaIO);
2931 newexpr->arg = (Expr *) linitial(args);
2932 newexpr->resulttype = expr->resulttype;
2933 newexpr->resultcollid = expr->resultcollid;
2934 newexpr->coerceformat = expr->coerceformat;
2935 newexpr->location = expr->location;
2936 return (Node *) newexpr;
2937 }
2938 case T_ArrayCoerceExpr:
2939 {
2940 ArrayCoerceExpr *ac = makeNode(ArrayCoerceExpr);
2941 Node *save_case_val;
2942
2943 /*
2944 * Copy the node and const-simplify its arguments. We can't
2945 * use ece_generic_processing() here because we need to mess
2946 * with case_val only while processing the elemexpr.
2947 */
2948 memcpy(ac, node, sizeof(ArrayCoerceExpr));
2949 ac->arg = (Expr *)
2950 eval_const_expressions_mutator((Node *) ac->arg,
2951 context);
2952
2953 /*
2954 * Set up for the CaseTestExpr node contained in the elemexpr.
2955 * We must prevent it from absorbing any outer CASE value.
2956 */
2957 save_case_val = context->case_val;
2958 context->case_val = NULL;
2959
2960 ac->elemexpr = (Expr *)
2961 eval_const_expressions_mutator((Node *) ac->elemexpr,
2962 context);
2963
2964 context->case_val = save_case_val;
2965
2966 /*
2967 * If constant argument and the per-element expression is
2968 * immutable, we can simplify the whole thing to a constant.
2969 * Exception: although contain_mutable_functions considers
2970 * CoerceToDomain immutable for historical reasons, let's not
2971 * do so here; this ensures coercion to an array-over-domain
2972 * does not apply the domain's constraints until runtime.
2973 */
2974 if (ac->arg && IsA(ac->arg, Const) &&
2975 ac->elemexpr && !IsA(ac->elemexpr, CoerceToDomain) &&
2976 !contain_mutable_functions((Node *) ac->elemexpr))
2977 return ece_evaluate_expr(ac);
2978
2979 return (Node *) ac;
2980 }
2981 case T_CollateExpr:
2982 {
2983 /*
2984 * We replace CollateExpr with RelabelType, so as to improve
2985 * uniformity of expression representation and thus simplify
2986 * comparison of expressions. Hence this looks very nearly
2987 * the same as the RelabelType case, and we can apply the same
2988 * optimizations to avoid unnecessary RelabelTypes.
2989 */
2990 CollateExpr *collate = (CollateExpr *) node;
2991 Node *arg;
2992
2993 /* Simplify the input ... */
2994 arg = eval_const_expressions_mutator((Node *) collate->arg,
2995 context);
2996 /* ... and attach a new RelabelType node, if needed */
2997 return applyRelabelType(arg,
2998 exprType(arg),
2999 exprTypmod(arg),
3000 collate->collOid,
3001 COERCE_IMPLICIT_CAST,
3002 collate->location,
3003 true);
3004 }
3005 case T_CaseExpr:
3006 {
3007 /*----------
3008 * CASE expressions can be simplified if there are constant
3009 * condition clauses:
3010 * FALSE (or NULL): drop the alternative
3011 * TRUE: drop all remaining alternatives
3012 * If the first non-FALSE alternative is a constant TRUE,
3013 * we can simplify the entire CASE to that alternative's
3014 * expression. If there are no non-FALSE alternatives,
3015 * we simplify the entire CASE to the default result (ELSE).
3016 *
3017 * If we have a simple-form CASE with constant test
3018 * expression, we substitute the constant value for contained
3019 * CaseTestExpr placeholder nodes, so that we have the
3020 * opportunity to reduce constant test conditions. For
3021 * example this allows
3022 * CASE 0 WHEN 0 THEN 1 ELSE 1/0 END
3023 * to reduce to 1 rather than drawing a divide-by-0 error.
3024 * Note that when the test expression is constant, we don't
3025 * have to include it in the resulting CASE; for example
3026 * CASE 0 WHEN x THEN y ELSE z END
3027 * is transformed by the parser to
3028 * CASE 0 WHEN CaseTestExpr = x THEN y ELSE z END
3029 * which we can simplify to
3030 * CASE WHEN 0 = x THEN y ELSE z END
3031 * It is not necessary for the executor to evaluate the "arg"
3032 * expression when executing the CASE, since any contained
3033 * CaseTestExprs that might have referred to it will have been
3034 * replaced by the constant.
3035 *----------
3036 */
3037 CaseExpr *caseexpr = (CaseExpr *) node;
3038 CaseExpr *newcase;
3039 Node *save_case_val;
3040 Node *newarg;
3041 List *newargs;
3042 bool const_true_cond;
3043 Node *defresult = NULL;
3044 ListCell *arg;
3045
3046 /* Simplify the test expression, if any */
3047 newarg = eval_const_expressions_mutator((Node *) caseexpr->arg,
3048 context);
3049
3050 /* Set up for contained CaseTestExpr nodes */
3051 save_case_val = context->case_val;
3052 if (newarg && IsA(newarg, Const))
3053 {
3054 context->case_val = newarg;
3055 newarg = NULL; /* not needed anymore, see above */
3056 }
3057 else
3058 context->case_val = NULL;
3059
3060 /* Simplify the WHEN clauses */
3061 newargs = NIL;
3062 const_true_cond = false;
3063 foreach(arg, caseexpr->args)
3064 {
3065 CaseWhen *oldcasewhen = lfirst_node(CaseWhen, arg);
3066 Node *casecond;
3067 Node *caseresult;
3068
3069 /* Simplify this alternative's test condition */
3070 casecond = eval_const_expressions_mutator((Node *) oldcasewhen->expr,
3071 context);
3072
3073 /*
3074 * If the test condition is constant FALSE (or NULL), then
3075 * drop this WHEN clause completely, without processing
3076 * the result.
3077 */
3078 if (casecond && IsA(casecond, Const))
3079 {
3080 Const *const_input = (Const *) casecond;
3081
3082 if (const_input->constisnull ||
3083 !DatumGetBool(const_input->constvalue))
3084 continue; /* drop alternative with FALSE cond */
3085 /* Else it's constant TRUE */
3086 const_true_cond = true;
3087 }
3088
3089 /* Simplify this alternative's result value */
3090 caseresult = eval_const_expressions_mutator((Node *) oldcasewhen->result,
3091 context);
3092
3093 /* If non-constant test condition, emit a new WHEN node */
3094 if (!const_true_cond)
3095 {
3096 CaseWhen *newcasewhen = makeNode(CaseWhen);
3097
3098 newcasewhen->expr = (Expr *) casecond;
3099 newcasewhen->result = (Expr *) caseresult;
3100 newcasewhen->location = oldcasewhen->location;
3101 newargs = lappend(newargs, newcasewhen);
3102 continue;
3103 }
3104
3105 /*
3106 * Found a TRUE condition, so none of the remaining
3107 * alternatives can be reached. We treat the result as
3108 * the default result.
3109 */
3110 defresult = caseresult;
3111 break;
3112 }
3113
3114 /* Simplify the default result, unless we replaced it above */
3115 if (!const_true_cond)
3116 defresult = eval_const_expressions_mutator((Node *) caseexpr->defresult,
3117 context);
3118
3119 context->case_val = save_case_val;
3120
3121 /*
3122 * If no non-FALSE alternatives, CASE reduces to the default
3123 * result
3124 */
3125 if (newargs == NIL)
3126 return defresult;
3127 /* Otherwise we need a new CASE node */
3128 newcase = makeNode(CaseExpr);
3129 newcase->casetype = caseexpr->casetype;
3130 newcase->casecollid = caseexpr->casecollid;
3131 newcase->arg = (Expr *) newarg;
3132 newcase->args = newargs;
3133 newcase->defresult = (Expr *) defresult;
3134 newcase->location = caseexpr->location;
3135 return (Node *) newcase;
3136 }
3137 case T_CaseTestExpr:
3138 {
3139 /*
3140 * If we know a constant test value for the current CASE
3141 * construct, substitute it for the placeholder. Else just
3142 * return the placeholder as-is.
3143 */
3144 if (context->case_val)
3145 return copyObject(context->case_val);
3146 else
3147 return copyObject(node);
3148 }
3149 case T_SubscriptingRef:
3150 case T_ArrayExpr:
3151 case T_RowExpr:
3152 case T_MinMaxExpr:
3153 {
3154 /*
3155 * Generic handling for node types whose own processing is
3156 * known to be immutable, and for which we need no smarts
3157 * beyond "simplify if all inputs are constants".
3158 *
3159 * Treating MinMaxExpr this way amounts to assuming that the
3160 * btree comparison function it calls is immutable; see the
3161 * reasoning in contain_mutable_functions_walker.
3162 */
3163
3164 /* Copy the node and const-simplify its arguments */
3165 node = ece_generic_processing(node);
3166 /* If all arguments are Consts, we can fold to a constant */
3167 if (ece_all_arguments_const(node))
3168 return ece_evaluate_expr(node);
3169 return node;
3170 }
3171 case T_CoalesceExpr:
3172 {
3173 CoalesceExpr *coalesceexpr = (CoalesceExpr *) node;
3174 CoalesceExpr *newcoalesce;
3175 List *newargs;
3176 ListCell *arg;
3177
3178 newargs = NIL;
3179 foreach(arg, coalesceexpr->args)
3180 {
3181 Node *e;
3182
3183 e = eval_const_expressions_mutator((Node *) lfirst(arg),
3184 context);
3185
3186 /*
3187 * We can remove null constants from the list. For a
3188 * non-null constant, if it has not been preceded by any
3189 * other non-null-constant expressions then it is the
3190 * result. Otherwise, it's the next argument, but we can
3191 * drop following arguments since they will never be
3192 * reached.
3193 */
3194 if (IsA(e, Const))
3195 {
3196 if (((Const *) e)->constisnull)
3197 continue; /* drop null constant */
3198 if (newargs == NIL)
3199 return e; /* first expr */
3200 newargs = lappend(newargs, e);
3201 break;
3202 }
3203 newargs = lappend(newargs, e);
3204 }
3205
3206 /*
3207 * If all the arguments were constant null, the result is just
3208 * null
3209 */
3210 if (newargs == NIL)
3211 return (Node *) makeNullConst(coalesceexpr->coalescetype,
3212 -1,
3213 coalesceexpr->coalescecollid);
3214
3215 newcoalesce = makeNode(CoalesceExpr);
3216 newcoalesce->coalescetype = coalesceexpr->coalescetype;
3217 newcoalesce->coalescecollid = coalesceexpr->coalescecollid;
3218 newcoalesce->args = newargs;
3219 newcoalesce->location = coalesceexpr->location;
3220 return (Node *) newcoalesce;
3221 }
3222 case T_SQLValueFunction:
3223 {
3224 /*
3225 * All variants of SQLValueFunction are stable, so if we are
3226 * estimating the expression's value, we should evaluate the
3227 * current function value. Otherwise just copy.
3228 */
3229 SQLValueFunction *svf = (SQLValueFunction *) node;
3230
3231 if (context->estimate)
3232 return (Node *) evaluate_expr((Expr *) svf,
3233 svf->type,
3234 svf->typmod,
3235 InvalidOid);
3236 else
3237 return copyObject((Node *) svf);
3238 }
3239 case T_FieldSelect:
3240 {
3241 /*
3242 * We can optimize field selection from a whole-row Var into a
3243 * simple Var. (This case won't be generated directly by the
3244 * parser, because ParseComplexProjection short-circuits it.
3245 * But it can arise while simplifying functions.) Also, we
3246 * can optimize field selection from a RowExpr construct, or
3247 * of course from a constant.
3248 *
3249 * However, replacing a whole-row Var in this way has a
3250 * pitfall: if we've already built the rel targetlist for the
3251 * source relation, then the whole-row Var is scheduled to be
3252 * produced by the relation scan, but the simple Var probably
3253 * isn't, which will lead to a failure in setrefs.c. This is
3254 * not a problem when handling simple single-level queries, in
3255 * which expression simplification always happens first. It
3256 * is a risk for lateral references from subqueries, though.
3257 * To avoid such failures, don't optimize uplevel references.
3258 *
3259 * We must also check that the declared type of the field is
3260 * still the same as when the FieldSelect was created --- this
3261 * can change if someone did ALTER COLUMN TYPE on the rowtype.
3262 * If it isn't, we skip the optimization; the case will
3263 * probably fail at runtime, but that's not our problem here.
3264 */
3265 FieldSelect *fselect = (FieldSelect *) node;
3266 FieldSelect *newfselect;
3267 Node *arg;
3268
3269 arg = eval_const_expressions_mutator((Node *) fselect->arg,
3270 context);
3271 if (arg && IsA(arg, Var) &&
3272 ((Var *) arg)->varattno == InvalidAttrNumber &&
3273 ((Var *) arg)->varlevelsup == 0)
3274 {
3275 if (rowtype_field_matches(((Var *) arg)->vartype,
3276 fselect->fieldnum,
3277 fselect->resulttype,
3278 fselect->resulttypmod,
3279 fselect->resultcollid))
3280 return (Node *) makeVar(((Var *) arg)->varno,
3281 fselect->fieldnum,
3282 fselect->resulttype,
3283 fselect->resulttypmod,
3284 fselect->resultcollid,
3285 ((Var *) arg)->varlevelsup);
3286 }
3287 if (arg && IsA(arg, RowExpr))
3288 {
3289 RowExpr *rowexpr = (RowExpr *) arg;
3290
3291 if (fselect->fieldnum > 0 &&
3292 fselect->fieldnum <= list_length(rowexpr->args))
3293 {
3294 Node *fld = (Node *) list_nth(rowexpr->args,
3295 fselect->fieldnum - 1);
3296
3297 if (rowtype_field_matches(rowexpr->row_typeid,
3298 fselect->fieldnum,
3299 fselect->resulttype,
3300 fselect->resulttypmod,
3301 fselect->resultcollid) &&
3302 fselect->resulttype == exprType(fld) &&
3303 fselect->resulttypmod == exprTypmod(fld) &&
3304 fselect->resultcollid == exprCollation(fld))
3305 return fld;
3306 }
3307 }
3308 newfselect = makeNode(FieldSelect);
3309 newfselect->arg = (Expr *) arg;
3310 newfselect->fieldnum = fselect->fieldnum;
3311 newfselect->resulttype = fselect->resulttype;
3312 newfselect->resulttypmod = fselect->resulttypmod;
3313 newfselect->resultcollid = fselect->resultcollid;
3314 if (arg && IsA(arg, Const))
3315 {
3316 Const *con = (Const *) arg;
3317
3318 if (rowtype_field_matches(con->consttype,
3319 newfselect->fieldnum,
3320 newfselect->resulttype,
3321 newfselect->resulttypmod,
3322 newfselect->resultcollid))
3323 return ece_evaluate_expr(newfselect);
3324 }
3325 return (Node *) newfselect;
3326 }
3327 case T_NullTest:
3328 {
3329 NullTest *ntest = (NullTest *) node;
3330 NullTest *newntest;
3331 Node *arg;
3332
3333 arg = eval_const_expressions_mutator((Node *) ntest->arg,
3334 context);
3335 if (ntest->argisrow && arg && IsA(arg, RowExpr))
3336 {
3337 /*
3338 * We break ROW(...) IS [NOT] NULL into separate tests on
3339 * its component fields. This form is usually more
3340 * efficient to evaluate, as well as being more amenable
3341 * to optimization.
3342 */
3343 RowExpr *rarg = (RowExpr *) arg;
3344 List *newargs = NIL;
3345 ListCell *l;
3346
3347 foreach(l, rarg->args)
3348 {
3349 Node *relem = (Node *) lfirst(l);
3350
3351 /*
3352 * A constant field refutes the whole NullTest if it's
3353 * of the wrong nullness; else we can discard it.
3354 */
3355 if (relem && IsA(relem, Const))
3356 {
3357 Const *carg = (Const *) relem;
3358
3359 if (carg->constisnull ?
3360 (ntest->nulltesttype == IS_NOT_NULL) :
3361 (ntest->nulltesttype == IS_NULL))
3362 return makeBoolConst(false, false);
3363 continue;
3364 }
3365
3366 /*
3367 * Else, make a scalar (argisrow == false) NullTest
3368 * for this field. Scalar semantics are required
3369 * because IS [NOT] NULL doesn't recurse; see comments
3370 * in ExecEvalRowNullInt().
3371 */
3372 newntest = makeNode(NullTest);
3373 newntest->arg = (Expr *) relem;
3374 newntest->nulltesttype = ntest->nulltesttype;
3375 newntest->argisrow = false;
3376 newntest->location = ntest->location;
3377 newargs = lappend(newargs, newntest);
3378 }
3379 /* If all the inputs were constants, result is TRUE */
3380 if (newargs == NIL)
3381 return makeBoolConst(true, false);
3382 /* If only one nonconst input, it's the result */
3383 if (list_length(newargs) == 1)
3384 return (Node *) linitial(newargs);
3385 /* Else we need an AND node */
3386 return (Node *) make_andclause(newargs);
3387 }
3388 if (!ntest->argisrow && arg && IsA(arg, Const))
3389 {
3390 Const *carg = (Const *) arg;
3391 bool result;
3392
3393 switch (ntest->nulltesttype)
3394 {
3395 case IS_NULL:
3396 result = carg->constisnull;
3397 break;
3398 case IS_NOT_NULL:
3399 result = !carg->constisnull;
3400 break;
3401 default:
3402 elog(ERROR, "unrecognized nulltesttype: %d",
3403 (int) ntest->nulltesttype);
3404 result = false; /* keep compiler quiet */
3405 break;
3406 }
3407
3408 return makeBoolConst(result, false);
3409 }
3410
3411 newntest = makeNode(NullTest);
3412 newntest->arg = (Expr *) arg;
3413 newntest->nulltesttype = ntest->nulltesttype;
3414 newntest->argisrow = ntest->argisrow;
3415 newntest->location = ntest->location;
3416 return (Node *) newntest;
3417 }
3418 case T_BooleanTest:
3419 {
3420 /*
3421 * This case could be folded into the generic handling used
3422 * for SubscriptingRef etc. But because the simplification
3423 * logic is so trivial, applying evaluate_expr() to perform it
3424 * would be a heavy overhead. BooleanTest is probably common
3425 * enough to justify keeping this bespoke implementation.
3426 */
3427 BooleanTest *btest = (BooleanTest *) node;
3428 BooleanTest *newbtest;
3429 Node *arg;
3430
3431 arg = eval_const_expressions_mutator((Node *) btest->arg,
3432 context);
3433 if (arg && IsA(arg, Const))
3434 {
3435 Const *carg = (Const *) arg;
3436 bool result;
3437
3438 switch (btest->booltesttype)
3439 {
3440 case IS_TRUE:
3441 result = (!carg->constisnull &&
3442 DatumGetBool(carg->constvalue));
3443 break;
3444 case IS_NOT_TRUE:
3445 result = (carg->constisnull ||
3446 !DatumGetBool(carg->constvalue));
3447 break;
3448 case IS_FALSE:
3449 result = (!carg->constisnull &&
3450 !DatumGetBool(carg->constvalue));
3451 break;
3452 case IS_NOT_FALSE:
3453 result = (carg->constisnull ||
3454 DatumGetBool(carg->constvalue));
3455 break;
3456 case IS_UNKNOWN:
3457 result = carg->constisnull;
3458 break;
3459 case IS_NOT_UNKNOWN:
3460 result = !carg->constisnull;
3461 break;
3462 default:
3463 elog(ERROR, "unrecognized booltesttype: %d",
3464 (int) btest->booltesttype);
3465 result = false; /* keep compiler quiet */
3466 break;
3467 }
3468
3469 return makeBoolConst(result, false);
3470 }
3471
3472 newbtest = makeNode(BooleanTest);
3473 newbtest->arg = (Expr *) arg;
3474 newbtest->booltesttype = btest->booltesttype;
3475 newbtest->location = btest->location;
3476 return (Node *) newbtest;
3477 }
3478 case T_CoerceToDomain:
3479 {
3480 /*
3481 * If the domain currently has no constraints, we replace the
3482 * CoerceToDomain node with a simple RelabelType, which is
3483 * both far faster to execute and more amenable to later
3484 * optimization. We must then mark the plan as needing to be
3485 * rebuilt if the domain's constraints change.
3486 *
3487 * Also, in estimation mode, always replace CoerceToDomain
3488 * nodes, effectively assuming that the coercion will succeed.
3489 */
3490 CoerceToDomain *cdomain = (CoerceToDomain *) node;
3491 CoerceToDomain *newcdomain;
3492 Node *arg;
3493
3494 arg = eval_const_expressions_mutator((Node *) cdomain->arg,
3495 context);
3496 if (context->estimate ||
3497 !DomainHasConstraints(cdomain->resulttype))
3498 {
3499 /* Record dependency, if this isn't estimation mode */
3500 if (context->root && !context->estimate)
3501 record_plan_type_dependency(context->root,
3502 cdomain->resulttype);
3503
3504 /* Generate RelabelType to substitute for CoerceToDomain */
3505 return applyRelabelType(arg,
3506 cdomain->resulttype,
3507 cdomain->resulttypmod,
3508 cdomain->resultcollid,
3509 cdomain->coercionformat,
3510 cdomain->location,
3511 true);
3512 }
3513
3514 newcdomain = makeNode(CoerceToDomain);
3515 newcdomain->arg = (Expr *) arg;
3516 newcdomain->resulttype = cdomain->resulttype;
3517 newcdomain->resulttypmod = cdomain->resulttypmod;
3518 newcdomain->resultcollid = cdomain->resultcollid;
3519 newcdomain->coercionformat = cdomain->coercionformat;
3520 newcdomain->location = cdomain->location;
3521 return (Node *) newcdomain;
3522 }
3523 case T_PlaceHolderVar:
3524
3525 /*
3526 * In estimation mode, just strip the PlaceHolderVar node
3527 * altogether; this amounts to estimating that the contained value
3528 * won't be forced to null by an outer join. In regular mode we
3529 * just use the default behavior (ie, simplify the expression but
3530 * leave the PlaceHolderVar node intact).
3531 */
3532 if (context->estimate)
3533 {
3534 PlaceHolderVar *phv = (PlaceHolderVar *) node;
3535
3536 return eval_const_expressions_mutator((Node *) phv->phexpr,
3537 context);
3538 }
3539 break;
3540 case T_ConvertRowtypeExpr:
3541 {
3542 ConvertRowtypeExpr *cre = castNode(ConvertRowtypeExpr, node);
3543 Node *arg;
3544 ConvertRowtypeExpr *newcre;
3545
3546 arg = eval_const_expressions_mutator((Node *) cre->arg,
3547 context);
3548
3549 newcre = makeNode(ConvertRowtypeExpr);
3550 newcre->resulttype = cre->resulttype;
3551 newcre->convertformat = cre->convertformat;
3552 newcre->location = cre->location;
3553
3554 /*
3555 * In case of a nested ConvertRowtypeExpr, we can convert the
3556 * leaf row directly to the topmost row format without any
3557 * intermediate conversions. (This works because
3558 * ConvertRowtypeExpr is used only for child->parent
3559 * conversion in inheritance trees, which works by exact match
3560 * of column name, and a column absent in an intermediate
3561 * result can't be present in the final result.)
3562 *
3563 * No need to check more than one level deep, because the
3564 * above recursion will have flattened anything else.
3565 */
3566 if (arg != NULL && IsA(arg, ConvertRowtypeExpr))
3567 {
3568 ConvertRowtypeExpr *argcre = (ConvertRowtypeExpr *) arg;
3569
3570 arg = (Node *) argcre->arg;
3571
3572 /*
3573 * Make sure an outer implicit conversion can't hide an
3574 * inner explicit one.
3575 */
3576 if (newcre->convertformat == COERCE_IMPLICIT_CAST)
3577 newcre->convertformat = argcre->convertformat;
3578 }
3579
3580 newcre->arg = (Expr *) arg;
3581
3582 if (arg != NULL && IsA(arg, Const))
3583 return ece_evaluate_expr((Node *) newcre);
3584 return (Node *) newcre;
3585 }
3586 default:
3587 break;
3588 }
3589
3590 /*
3591 * For any node type not handled above, copy the node unchanged but
3592 * const-simplify its subexpressions. This is the correct thing for node
3593 * types whose behavior might change between planning and execution, such
3594 * as CurrentOfExpr. It's also a safe default for new node types not
3595 * known to this routine.
3596 */
3597 return ece_generic_processing(node);
3598 }
3599
3600 /*
3601 * Subroutine for eval_const_expressions: check for non-Const nodes.
3602 *
3603 * We can abort recursion immediately on finding a non-Const node. This is
3604 * critical for performance, else eval_const_expressions_mutator would take
3605 * O(N^2) time on non-simplifiable trees. However, we do need to descend
3606 * into List nodes since expression_tree_walker sometimes invokes the walker
3607 * function directly on List subtrees.
3608 */
3609 static bool
contain_non_const_walker(Node * node,void * context)3610 contain_non_const_walker(Node *node, void *context)
3611 {
3612 if (node == NULL)
3613 return false;
3614 if (IsA(node, Const))
3615 return false;
3616 if (IsA(node, List))
3617 return expression_tree_walker(node, contain_non_const_walker, context);
3618 /* Otherwise, abort the tree traversal and return true */
3619 return true;
3620 }
3621
3622 /*
3623 * Subroutine for eval_const_expressions: check if a function is OK to evaluate
3624 */
3625 static bool
ece_function_is_safe(Oid funcid,eval_const_expressions_context * context)3626 ece_function_is_safe(Oid funcid, eval_const_expressions_context *context)
3627 {
3628 char provolatile = func_volatile(funcid);
3629
3630 /*
3631 * Ordinarily we are only allowed to simplify immutable functions. But for
3632 * purposes of estimation, we consider it okay to simplify functions that
3633 * are merely stable; the risk that the result might change from planning
3634 * time to execution time is worth taking in preference to not being able
3635 * to estimate the value at all.
3636 */
3637 if (provolatile == PROVOLATILE_IMMUTABLE)
3638 return true;
3639 if (context->estimate && provolatile == PROVOLATILE_STABLE)
3640 return true;
3641 return false;
3642 }
3643
3644 /*
3645 * Subroutine for eval_const_expressions: process arguments of an OR clause
3646 *
3647 * This includes flattening of nested ORs as well as recursion to
3648 * eval_const_expressions to simplify the OR arguments.
3649 *
3650 * After simplification, OR arguments are handled as follows:
3651 * non constant: keep
3652 * FALSE: drop (does not affect result)
3653 * TRUE: force result to TRUE
3654 * NULL: keep only one
3655 * We must keep one NULL input because OR expressions evaluate to NULL when no
3656 * input is TRUE and at least one is NULL. We don't actually include the NULL
3657 * here, that's supposed to be done by the caller.
3658 *
3659 * The output arguments *haveNull and *forceTrue must be initialized false
3660 * by the caller. They will be set true if a NULL constant or TRUE constant,
3661 * respectively, is detected anywhere in the argument list.
3662 */
3663 static List *
simplify_or_arguments(List * args,eval_const_expressions_context * context,bool * haveNull,bool * forceTrue)3664 simplify_or_arguments(List *args,
3665 eval_const_expressions_context *context,
3666 bool *haveNull, bool *forceTrue)
3667 {
3668 List *newargs = NIL;
3669 List *unprocessed_args;
3670
3671 /*
3672 * We want to ensure that any OR immediately beneath another OR gets
3673 * flattened into a single OR-list, so as to simplify later reasoning.
3674 *
3675 * To avoid stack overflow from recursion of eval_const_expressions, we
3676 * resort to some tenseness here: we keep a list of not-yet-processed
3677 * inputs, and handle flattening of nested ORs by prepending to the to-do
3678 * list instead of recursing. Now that the parser generates N-argument
3679 * ORs from simple lists, this complexity is probably less necessary than
3680 * it once was, but we might as well keep the logic.
3681 */
3682 unprocessed_args = list_copy(args);
3683 while (unprocessed_args)
3684 {
3685 Node *arg = (Node *) linitial(unprocessed_args);
3686
3687 unprocessed_args = list_delete_first(unprocessed_args);
3688
3689 /* flatten nested ORs as per above comment */
3690 if (is_orclause(arg))
3691 {
3692 List *subargs = ((BoolExpr *) arg)->args;
3693 List *oldlist = unprocessed_args;
3694
3695 unprocessed_args = list_concat_copy(subargs, unprocessed_args);
3696 /* perhaps-overly-tense code to avoid leaking old lists */
3697 list_free(oldlist);
3698 continue;
3699 }
3700
3701 /* If it's not an OR, simplify it */
3702 arg = eval_const_expressions_mutator(arg, context);
3703
3704 /*
3705 * It is unlikely but not impossible for simplification of a non-OR
3706 * clause to produce an OR. Recheck, but don't be too tense about it
3707 * since it's not a mainstream case. In particular we don't worry
3708 * about const-simplifying the input twice, nor about list leakage.
3709 */
3710 if (is_orclause(arg))
3711 {
3712 List *subargs = ((BoolExpr *) arg)->args;
3713
3714 unprocessed_args = list_concat_copy(subargs, unprocessed_args);
3715 continue;
3716 }
3717
3718 /*
3719 * OK, we have a const-simplified non-OR argument. Process it per
3720 * comments above.
3721 */
3722 if (IsA(arg, Const))
3723 {
3724 Const *const_input = (Const *) arg;
3725
3726 if (const_input->constisnull)
3727 *haveNull = true;
3728 else if (DatumGetBool(const_input->constvalue))
3729 {
3730 *forceTrue = true;
3731
3732 /*
3733 * Once we detect a TRUE result we can just exit the loop
3734 * immediately. However, if we ever add a notion of
3735 * non-removable functions, we'd need to keep scanning.
3736 */
3737 return NIL;
3738 }
3739 /* otherwise, we can drop the constant-false input */
3740 continue;
3741 }
3742
3743 /* else emit the simplified arg into the result list */
3744 newargs = lappend(newargs, arg);
3745 }
3746
3747 return newargs;
3748 }
3749
3750 /*
3751 * Subroutine for eval_const_expressions: process arguments of an AND clause
3752 *
3753 * This includes flattening of nested ANDs as well as recursion to
3754 * eval_const_expressions to simplify the AND arguments.
3755 *
3756 * After simplification, AND arguments are handled as follows:
3757 * non constant: keep
3758 * TRUE: drop (does not affect result)
3759 * FALSE: force result to FALSE
3760 * NULL: keep only one
3761 * We must keep one NULL input because AND expressions evaluate to NULL when
3762 * no input is FALSE and at least one is NULL. We don't actually include the
3763 * NULL here, that's supposed to be done by the caller.
3764 *
3765 * The output arguments *haveNull and *forceFalse must be initialized false
3766 * by the caller. They will be set true if a null constant or false constant,
3767 * respectively, is detected anywhere in the argument list.
3768 */
3769 static List *
simplify_and_arguments(List * args,eval_const_expressions_context * context,bool * haveNull,bool * forceFalse)3770 simplify_and_arguments(List *args,
3771 eval_const_expressions_context *context,
3772 bool *haveNull, bool *forceFalse)
3773 {
3774 List *newargs = NIL;
3775 List *unprocessed_args;
3776
3777 /* See comments in simplify_or_arguments */
3778 unprocessed_args = list_copy(args);
3779 while (unprocessed_args)
3780 {
3781 Node *arg = (Node *) linitial(unprocessed_args);
3782
3783 unprocessed_args = list_delete_first(unprocessed_args);
3784
3785 /* flatten nested ANDs as per above comment */
3786 if (is_andclause(arg))
3787 {
3788 List *subargs = ((BoolExpr *) arg)->args;
3789 List *oldlist = unprocessed_args;
3790
3791 unprocessed_args = list_concat_copy(subargs, unprocessed_args);
3792 /* perhaps-overly-tense code to avoid leaking old lists */
3793 list_free(oldlist);
3794 continue;
3795 }
3796
3797 /* If it's not an AND, simplify it */
3798 arg = eval_const_expressions_mutator(arg, context);
3799
3800 /*
3801 * It is unlikely but not impossible for simplification of a non-AND
3802 * clause to produce an AND. Recheck, but don't be too tense about it
3803 * since it's not a mainstream case. In particular we don't worry
3804 * about const-simplifying the input twice, nor about list leakage.
3805 */
3806 if (is_andclause(arg))
3807 {
3808 List *subargs = ((BoolExpr *) arg)->args;
3809
3810 unprocessed_args = list_concat_copy(subargs, unprocessed_args);
3811 continue;
3812 }
3813
3814 /*
3815 * OK, we have a const-simplified non-AND argument. Process it per
3816 * comments above.
3817 */
3818 if (IsA(arg, Const))
3819 {
3820 Const *const_input = (Const *) arg;
3821
3822 if (const_input->constisnull)
3823 *haveNull = true;
3824 else if (!DatumGetBool(const_input->constvalue))
3825 {
3826 *forceFalse = true;
3827
3828 /*
3829 * Once we detect a FALSE result we can just exit the loop
3830 * immediately. However, if we ever add a notion of
3831 * non-removable functions, we'd need to keep scanning.
3832 */
3833 return NIL;
3834 }
3835 /* otherwise, we can drop the constant-true input */
3836 continue;
3837 }
3838
3839 /* else emit the simplified arg into the result list */
3840 newargs = lappend(newargs, arg);
3841 }
3842
3843 return newargs;
3844 }
3845
3846 /*
3847 * Subroutine for eval_const_expressions: try to simplify boolean equality
3848 * or inequality condition
3849 *
3850 * Inputs are the operator OID and the simplified arguments to the operator.
3851 * Returns a simplified expression if successful, or NULL if cannot
3852 * simplify the expression.
3853 *
3854 * The idea here is to reduce "x = true" to "x" and "x = false" to "NOT x",
3855 * or similarly "x <> true" to "NOT x" and "x <> false" to "x".
3856 * This is only marginally useful in itself, but doing it in constant folding
3857 * ensures that we will recognize these forms as being equivalent in, for
3858 * example, partial index matching.
3859 *
3860 * We come here only if simplify_function has failed; therefore we cannot
3861 * see two constant inputs, nor a constant-NULL input.
3862 */
3863 static Node *
simplify_boolean_equality(Oid opno,List * args)3864 simplify_boolean_equality(Oid opno, List *args)
3865 {
3866 Node *leftop;
3867 Node *rightop;
3868
3869 Assert(list_length(args) == 2);
3870 leftop = linitial(args);
3871 rightop = lsecond(args);
3872 if (leftop && IsA(leftop, Const))
3873 {
3874 Assert(!((Const *) leftop)->constisnull);
3875 if (opno == BooleanEqualOperator)
3876 {
3877 if (DatumGetBool(((Const *) leftop)->constvalue))
3878 return rightop; /* true = foo */
3879 else
3880 return negate_clause(rightop); /* false = foo */
3881 }
3882 else
3883 {
3884 if (DatumGetBool(((Const *) leftop)->constvalue))
3885 return negate_clause(rightop); /* true <> foo */
3886 else
3887 return rightop; /* false <> foo */
3888 }
3889 }
3890 if (rightop && IsA(rightop, Const))
3891 {
3892 Assert(!((Const *) rightop)->constisnull);
3893 if (opno == BooleanEqualOperator)
3894 {
3895 if (DatumGetBool(((Const *) rightop)->constvalue))
3896 return leftop; /* foo = true */
3897 else
3898 return negate_clause(leftop); /* foo = false */
3899 }
3900 else
3901 {
3902 if (DatumGetBool(((Const *) rightop)->constvalue))
3903 return negate_clause(leftop); /* foo <> true */
3904 else
3905 return leftop; /* foo <> false */
3906 }
3907 }
3908 return NULL;
3909 }
3910
3911 /*
3912 * Subroutine for eval_const_expressions: try to simplify a function call
3913 * (which might originally have been an operator; we don't care)
3914 *
3915 * Inputs are the function OID, actual result type OID (which is needed for
3916 * polymorphic functions), result typmod, result collation, the input
3917 * collation to use for the function, the original argument list (not
3918 * const-simplified yet, unless process_args is false), and some flags;
3919 * also the context data for eval_const_expressions.
3920 *
3921 * Returns a simplified expression if successful, or NULL if cannot
3922 * simplify the function call.
3923 *
3924 * This function is also responsible for converting named-notation argument
3925 * lists into positional notation and/or adding any needed default argument
3926 * expressions; which is a bit grotty, but it avoids extra fetches of the
3927 * function's pg_proc tuple. For this reason, the args list is
3928 * pass-by-reference. Conversion and const-simplification of the args list
3929 * will be done even if simplification of the function call itself is not
3930 * possible.
3931 */
3932 static Expr *
simplify_function(Oid funcid,Oid result_type,int32 result_typmod,Oid result_collid,Oid input_collid,List ** args_p,bool funcvariadic,bool process_args,bool allow_non_const,eval_const_expressions_context * context)3933 simplify_function(Oid funcid, Oid result_type, int32 result_typmod,
3934 Oid result_collid, Oid input_collid, List **args_p,
3935 bool funcvariadic, bool process_args, bool allow_non_const,
3936 eval_const_expressions_context *context)
3937 {
3938 List *args = *args_p;
3939 HeapTuple func_tuple;
3940 Form_pg_proc func_form;
3941 Expr *newexpr;
3942
3943 /*
3944 * We have three strategies for simplification: execute the function to
3945 * deliver a constant result, use a transform function to generate a
3946 * substitute node tree, or expand in-line the body of the function
3947 * definition (which only works for simple SQL-language functions, but
3948 * that is a common case). Each case needs access to the function's
3949 * pg_proc tuple, so fetch it just once.
3950 *
3951 * Note: the allow_non_const flag suppresses both the second and third
3952 * strategies; so if !allow_non_const, simplify_function can only return a
3953 * Const or NULL. Argument-list rewriting happens anyway, though.
3954 */
3955 func_tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
3956 if (!HeapTupleIsValid(func_tuple))
3957 elog(ERROR, "cache lookup failed for function %u", funcid);
3958 func_form = (Form_pg_proc) GETSTRUCT(func_tuple);
3959
3960 /*
3961 * Process the function arguments, unless the caller did it already.
3962 *
3963 * Here we must deal with named or defaulted arguments, and then
3964 * recursively apply eval_const_expressions to the whole argument list.
3965 */
3966 if (process_args)
3967 {
3968 args = expand_function_arguments(args, result_type, func_tuple);
3969 args = (List *) expression_tree_mutator((Node *) args,
3970 eval_const_expressions_mutator,
3971 (void *) context);
3972 /* Argument processing done, give it back to the caller */
3973 *args_p = args;
3974 }
3975
3976 /* Now attempt simplification of the function call proper. */
3977
3978 newexpr = evaluate_function(funcid, result_type, result_typmod,
3979 result_collid, input_collid,
3980 args, funcvariadic,
3981 func_tuple, context);
3982
3983 if (!newexpr && allow_non_const && OidIsValid(func_form->prosupport))
3984 {
3985 /*
3986 * Build a SupportRequestSimplify node to pass to the support
3987 * function, pointing to a dummy FuncExpr node containing the
3988 * simplified arg list. We use this approach to present a uniform
3989 * interface to the support function regardless of how the target
3990 * function is actually being invoked.
3991 */
3992 SupportRequestSimplify req;
3993 FuncExpr fexpr;
3994
3995 fexpr.xpr.type = T_FuncExpr;
3996 fexpr.funcid = funcid;
3997 fexpr.funcresulttype = result_type;
3998 fexpr.funcretset = func_form->proretset;
3999 fexpr.funcvariadic = funcvariadic;
4000 fexpr.funcformat = COERCE_EXPLICIT_CALL;
4001 fexpr.funccollid = result_collid;
4002 fexpr.inputcollid = input_collid;
4003 fexpr.args = args;
4004 fexpr.location = -1;
4005
4006 req.type = T_SupportRequestSimplify;
4007 req.root = context->root;
4008 req.fcall = &fexpr;
4009
4010 newexpr = (Expr *)
4011 DatumGetPointer(OidFunctionCall1(func_form->prosupport,
4012 PointerGetDatum(&req)));
4013
4014 /* catch a possible API misunderstanding */
4015 Assert(newexpr != (Expr *) &fexpr);
4016 }
4017
4018 if (!newexpr && allow_non_const)
4019 newexpr = inline_function(funcid, result_type, result_collid,
4020 input_collid, args, funcvariadic,
4021 func_tuple, context);
4022
4023 ReleaseSysCache(func_tuple);
4024
4025 return newexpr;
4026 }
4027
4028 /*
4029 * expand_function_arguments: convert named-notation args to positional args
4030 * and/or insert default args, as needed
4031 *
4032 * If we need to change anything, the input argument list is copied, not
4033 * modified.
4034 *
4035 * Note: this gets applied to operator argument lists too, even though the
4036 * cases it handles should never occur there. This should be OK since it
4037 * will fall through very quickly if there's nothing to do.
4038 */
4039 List *
expand_function_arguments(List * args,Oid result_type,HeapTuple func_tuple)4040 expand_function_arguments(List *args, Oid result_type, HeapTuple func_tuple)
4041 {
4042 Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
4043 bool has_named_args = false;
4044 ListCell *lc;
4045
4046 /* Do we have any named arguments? */
4047 foreach(lc, args)
4048 {
4049 Node *arg = (Node *) lfirst(lc);
4050
4051 if (IsA(arg, NamedArgExpr))
4052 {
4053 has_named_args = true;
4054 break;
4055 }
4056 }
4057
4058 /* If so, we must apply reorder_function_arguments */
4059 if (has_named_args)
4060 {
4061 args = reorder_function_arguments(args, func_tuple);
4062 /* Recheck argument types and add casts if needed */
4063 recheck_cast_function_args(args, result_type, func_tuple);
4064 }
4065 else if (list_length(args) < funcform->pronargs)
4066 {
4067 /* No named args, but we seem to be short some defaults */
4068 args = add_function_defaults(args, func_tuple);
4069 /* Recheck argument types and add casts if needed */
4070 recheck_cast_function_args(args, result_type, func_tuple);
4071 }
4072
4073 return args;
4074 }
4075
4076 /*
4077 * reorder_function_arguments: convert named-notation args to positional args
4078 *
4079 * This function also inserts default argument values as needed, since it's
4080 * impossible to form a truly valid positional call without that.
4081 */
4082 static List *
reorder_function_arguments(List * args,HeapTuple func_tuple)4083 reorder_function_arguments(List *args, HeapTuple func_tuple)
4084 {
4085 Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
4086 int pronargs = funcform->pronargs;
4087 int nargsprovided = list_length(args);
4088 Node *argarray[FUNC_MAX_ARGS];
4089 ListCell *lc;
4090 int i;
4091
4092 Assert(nargsprovided <= pronargs);
4093 if (pronargs < 0 || pronargs > FUNC_MAX_ARGS)
4094 elog(ERROR, "too many function arguments");
4095 memset(argarray, 0, pronargs * sizeof(Node *));
4096
4097 /* Deconstruct the argument list into an array indexed by argnumber */
4098 i = 0;
4099 foreach(lc, args)
4100 {
4101 Node *arg = (Node *) lfirst(lc);
4102
4103 if (!IsA(arg, NamedArgExpr))
4104 {
4105 /* positional argument, assumed to precede all named args */
4106 Assert(argarray[i] == NULL);
4107 argarray[i++] = arg;
4108 }
4109 else
4110 {
4111 NamedArgExpr *na = (NamedArgExpr *) arg;
4112
4113 Assert(argarray[na->argnumber] == NULL);
4114 argarray[na->argnumber] = (Node *) na->arg;
4115 }
4116 }
4117
4118 /*
4119 * Fetch default expressions, if needed, and insert into array at proper
4120 * locations (they aren't necessarily consecutive or all used)
4121 */
4122 if (nargsprovided < pronargs)
4123 {
4124 List *defaults = fetch_function_defaults(func_tuple);
4125
4126 i = pronargs - funcform->pronargdefaults;
4127 foreach(lc, defaults)
4128 {
4129 if (argarray[i] == NULL)
4130 argarray[i] = (Node *) lfirst(lc);
4131 i++;
4132 }
4133 }
4134
4135 /* Now reconstruct the args list in proper order */
4136 args = NIL;
4137 for (i = 0; i < pronargs; i++)
4138 {
4139 Assert(argarray[i] != NULL);
4140 args = lappend(args, argarray[i]);
4141 }
4142
4143 return args;
4144 }
4145
4146 /*
4147 * add_function_defaults: add missing function arguments from its defaults
4148 *
4149 * This is used only when the argument list was positional to begin with,
4150 * and so we know we just need to add defaults at the end.
4151 */
4152 static List *
add_function_defaults(List * args,HeapTuple func_tuple)4153 add_function_defaults(List *args, HeapTuple func_tuple)
4154 {
4155 Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
4156 int nargsprovided = list_length(args);
4157 List *defaults;
4158 int ndelete;
4159
4160 /* Get all the default expressions from the pg_proc tuple */
4161 defaults = fetch_function_defaults(func_tuple);
4162
4163 /* Delete any unused defaults from the list */
4164 ndelete = nargsprovided + list_length(defaults) - funcform->pronargs;
4165 if (ndelete < 0)
4166 elog(ERROR, "not enough default arguments");
4167 if (ndelete > 0)
4168 defaults = list_delete_first_n(defaults, ndelete);
4169
4170 /* And form the combined argument list, not modifying the input list */
4171 return list_concat_copy(args, defaults);
4172 }
4173
4174 /*
4175 * fetch_function_defaults: get function's default arguments as expression list
4176 */
4177 static List *
fetch_function_defaults(HeapTuple func_tuple)4178 fetch_function_defaults(HeapTuple func_tuple)
4179 {
4180 List *defaults;
4181 Datum proargdefaults;
4182 bool isnull;
4183 char *str;
4184
4185 /* The error cases here shouldn't happen, but check anyway */
4186 proargdefaults = SysCacheGetAttr(PROCOID, func_tuple,
4187 Anum_pg_proc_proargdefaults,
4188 &isnull);
4189 if (isnull)
4190 elog(ERROR, "not enough default arguments");
4191 str = TextDatumGetCString(proargdefaults);
4192 defaults = castNode(List, stringToNode(str));
4193 pfree(str);
4194 return defaults;
4195 }
4196
4197 /*
4198 * recheck_cast_function_args: recheck function args and typecast as needed
4199 * after adding defaults.
4200 *
4201 * It is possible for some of the defaulted arguments to be polymorphic;
4202 * therefore we can't assume that the default expressions have the correct
4203 * data types already. We have to re-resolve polymorphics and do coercion
4204 * just like the parser did.
4205 *
4206 * This should be a no-op if there are no polymorphic arguments,
4207 * but we do it anyway to be sure.
4208 *
4209 * Note: if any casts are needed, the args list is modified in-place;
4210 * caller should have already copied the list structure.
4211 */
4212 static void
recheck_cast_function_args(List * args,Oid result_type,HeapTuple func_tuple)4213 recheck_cast_function_args(List *args, Oid result_type, HeapTuple func_tuple)
4214 {
4215 Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
4216 int nargs;
4217 Oid actual_arg_types[FUNC_MAX_ARGS];
4218 Oid declared_arg_types[FUNC_MAX_ARGS];
4219 Oid rettype;
4220 ListCell *lc;
4221
4222 if (list_length(args) > FUNC_MAX_ARGS)
4223 elog(ERROR, "too many function arguments");
4224 nargs = 0;
4225 foreach(lc, args)
4226 {
4227 actual_arg_types[nargs++] = exprType((Node *) lfirst(lc));
4228 }
4229 Assert(nargs == funcform->pronargs);
4230 memcpy(declared_arg_types, funcform->proargtypes.values,
4231 funcform->pronargs * sizeof(Oid));
4232 rettype = enforce_generic_type_consistency(actual_arg_types,
4233 declared_arg_types,
4234 nargs,
4235 funcform->prorettype,
4236 false);
4237 /* let's just check we got the same answer as the parser did ... */
4238 if (rettype != result_type)
4239 elog(ERROR, "function's resolved result type changed during planning");
4240
4241 /* perform any necessary typecasting of arguments */
4242 make_fn_arguments(NULL, args, actual_arg_types, declared_arg_types);
4243 }
4244
4245 /*
4246 * evaluate_function: try to pre-evaluate a function call
4247 *
4248 * We can do this if the function is strict and has any constant-null inputs
4249 * (just return a null constant), or if the function is immutable and has all
4250 * constant inputs (call it and return the result as a Const node). In
4251 * estimation mode we are willing to pre-evaluate stable functions too.
4252 *
4253 * Returns a simplified expression if successful, or NULL if cannot
4254 * simplify the function.
4255 */
4256 static Expr *
evaluate_function(Oid funcid,Oid result_type,int32 result_typmod,Oid result_collid,Oid input_collid,List * args,bool funcvariadic,HeapTuple func_tuple,eval_const_expressions_context * context)4257 evaluate_function(Oid funcid, Oid result_type, int32 result_typmod,
4258 Oid result_collid, Oid input_collid, List *args,
4259 bool funcvariadic,
4260 HeapTuple func_tuple,
4261 eval_const_expressions_context *context)
4262 {
4263 Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
4264 bool has_nonconst_input = false;
4265 bool has_null_input = false;
4266 ListCell *arg;
4267 FuncExpr *newexpr;
4268
4269 /*
4270 * Can't simplify if it returns a set.
4271 */
4272 if (funcform->proretset)
4273 return NULL;
4274
4275 /*
4276 * Can't simplify if it returns RECORD. The immediate problem is that it
4277 * will be needing an expected tupdesc which we can't supply here.
4278 *
4279 * In the case where it has OUT parameters, it could get by without an
4280 * expected tupdesc, but we still have issues: get_expr_result_type()
4281 * doesn't know how to extract type info from a RECORD constant, and in
4282 * the case of a NULL function result there doesn't seem to be any clean
4283 * way to fix that. In view of the likelihood of there being still other
4284 * gotchas, seems best to leave the function call unreduced.
4285 */
4286 if (funcform->prorettype == RECORDOID)
4287 return NULL;
4288
4289 /*
4290 * Check for constant inputs and especially constant-NULL inputs.
4291 */
4292 foreach(arg, args)
4293 {
4294 if (IsA(lfirst(arg), Const))
4295 has_null_input |= ((Const *) lfirst(arg))->constisnull;
4296 else
4297 has_nonconst_input = true;
4298 }
4299
4300 /*
4301 * If the function is strict and has a constant-NULL input, it will never
4302 * be called at all, so we can replace the call by a NULL constant, even
4303 * if there are other inputs that aren't constant, and even if the
4304 * function is not otherwise immutable.
4305 */
4306 if (funcform->proisstrict && has_null_input)
4307 return (Expr *) makeNullConst(result_type, result_typmod,
4308 result_collid);
4309
4310 /*
4311 * Otherwise, can simplify only if all inputs are constants. (For a
4312 * non-strict function, constant NULL inputs are treated the same as
4313 * constant non-NULL inputs.)
4314 */
4315 if (has_nonconst_input)
4316 return NULL;
4317
4318 /*
4319 * Ordinarily we are only allowed to simplify immutable functions. But for
4320 * purposes of estimation, we consider it okay to simplify functions that
4321 * are merely stable; the risk that the result might change from planning
4322 * time to execution time is worth taking in preference to not being able
4323 * to estimate the value at all.
4324 */
4325 if (funcform->provolatile == PROVOLATILE_IMMUTABLE)
4326 /* okay */ ;
4327 else if (context->estimate && funcform->provolatile == PROVOLATILE_STABLE)
4328 /* okay */ ;
4329 else
4330 return NULL;
4331
4332 /*
4333 * OK, looks like we can simplify this operator/function.
4334 *
4335 * Build a new FuncExpr node containing the already-simplified arguments.
4336 */
4337 newexpr = makeNode(FuncExpr);
4338 newexpr->funcid = funcid;
4339 newexpr->funcresulttype = result_type;
4340 newexpr->funcretset = false;
4341 newexpr->funcvariadic = funcvariadic;
4342 newexpr->funcformat = COERCE_EXPLICIT_CALL; /* doesn't matter */
4343 newexpr->funccollid = result_collid; /* doesn't matter */
4344 newexpr->inputcollid = input_collid;
4345 newexpr->args = args;
4346 newexpr->location = -1;
4347
4348 return evaluate_expr((Expr *) newexpr, result_type, result_typmod,
4349 result_collid);
4350 }
4351
4352 /*
4353 * inline_function: try to expand a function call inline
4354 *
4355 * If the function is a sufficiently simple SQL-language function
4356 * (just "SELECT expression"), then we can inline it and avoid the rather
4357 * high per-call overhead of SQL functions. Furthermore, this can expose
4358 * opportunities for constant-folding within the function expression.
4359 *
4360 * We have to beware of some special cases however. A directly or
4361 * indirectly recursive function would cause us to recurse forever,
4362 * so we keep track of which functions we are already expanding and
4363 * do not re-expand them. Also, if a parameter is used more than once
4364 * in the SQL-function body, we require it not to contain any volatile
4365 * functions (volatiles might deliver inconsistent answers) nor to be
4366 * unreasonably expensive to evaluate. The expensiveness check not only
4367 * prevents us from doing multiple evaluations of an expensive parameter
4368 * at runtime, but is a safety value to limit growth of an expression due
4369 * to repeated inlining.
4370 *
4371 * We must also beware of changing the volatility or strictness status of
4372 * functions by inlining them.
4373 *
4374 * Also, at the moment we can't inline functions returning RECORD. This
4375 * doesn't work in the general case because it discards information such
4376 * as OUT-parameter declarations.
4377 *
4378 * Also, context-dependent expression nodes in the argument list are trouble.
4379 *
4380 * Returns a simplified expression if successful, or NULL if cannot
4381 * simplify the function.
4382 */
4383 static Expr *
inline_function(Oid funcid,Oid result_type,Oid result_collid,Oid input_collid,List * args,bool funcvariadic,HeapTuple func_tuple,eval_const_expressions_context * context)4384 inline_function(Oid funcid, Oid result_type, Oid result_collid,
4385 Oid input_collid, List *args,
4386 bool funcvariadic,
4387 HeapTuple func_tuple,
4388 eval_const_expressions_context *context)
4389 {
4390 Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
4391 char *src;
4392 Datum tmp;
4393 bool isNull;
4394 MemoryContext oldcxt;
4395 MemoryContext mycxt;
4396 inline_error_callback_arg callback_arg;
4397 ErrorContextCallback sqlerrcontext;
4398 FuncExpr *fexpr;
4399 SQLFunctionParseInfoPtr pinfo;
4400 TupleDesc rettupdesc;
4401 ParseState *pstate;
4402 List *raw_parsetree_list;
4403 List *querytree_list;
4404 Query *querytree;
4405 Node *newexpr;
4406 int *usecounts;
4407 ListCell *arg;
4408 int i;
4409
4410 /*
4411 * Forget it if the function is not SQL-language or has other showstopper
4412 * properties. (The prokind and nargs checks are just paranoia.)
4413 */
4414 if (funcform->prolang != SQLlanguageId ||
4415 funcform->prokind != PROKIND_FUNCTION ||
4416 funcform->prosecdef ||
4417 funcform->proretset ||
4418 funcform->prorettype == RECORDOID ||
4419 !heap_attisnull(func_tuple, Anum_pg_proc_proconfig, NULL) ||
4420 funcform->pronargs != list_length(args))
4421 return NULL;
4422
4423 /* Check for recursive function, and give up trying to expand if so */
4424 if (list_member_oid(context->active_fns, funcid))
4425 return NULL;
4426
4427 /* Check permission to call function (fail later, if not) */
4428 if (pg_proc_aclcheck(funcid, GetUserId(), ACL_EXECUTE) != ACLCHECK_OK)
4429 return NULL;
4430
4431 /* Check whether a plugin wants to hook function entry/exit */
4432 if (FmgrHookIsNeeded(funcid))
4433 return NULL;
4434
4435 /*
4436 * Make a temporary memory context, so that we don't leak all the stuff
4437 * that parsing might create.
4438 */
4439 mycxt = AllocSetContextCreate(CurrentMemoryContext,
4440 "inline_function",
4441 ALLOCSET_DEFAULT_SIZES);
4442 oldcxt = MemoryContextSwitchTo(mycxt);
4443
4444 /* Fetch the function body */
4445 tmp = SysCacheGetAttr(PROCOID,
4446 func_tuple,
4447 Anum_pg_proc_prosrc,
4448 &isNull);
4449 if (isNull)
4450 elog(ERROR, "null prosrc for function %u", funcid);
4451 src = TextDatumGetCString(tmp);
4452
4453 /*
4454 * Setup error traceback support for ereport(). This is so that we can
4455 * finger the function that bad information came from.
4456 */
4457 callback_arg.proname = NameStr(funcform->proname);
4458 callback_arg.prosrc = src;
4459
4460 sqlerrcontext.callback = sql_inline_error_callback;
4461 sqlerrcontext.arg = (void *) &callback_arg;
4462 sqlerrcontext.previous = error_context_stack;
4463 error_context_stack = &sqlerrcontext;
4464
4465 /*
4466 * Set up to handle parameters while parsing the function body. We need a
4467 * dummy FuncExpr node containing the already-simplified arguments to pass
4468 * to prepare_sql_fn_parse_info. (In some cases we don't really need
4469 * that, but for simplicity we always build it.)
4470 */
4471 fexpr = makeNode(FuncExpr);
4472 fexpr->funcid = funcid;
4473 fexpr->funcresulttype = result_type;
4474 fexpr->funcretset = false;
4475 fexpr->funcvariadic = funcvariadic;
4476 fexpr->funcformat = COERCE_EXPLICIT_CALL; /* doesn't matter */
4477 fexpr->funccollid = result_collid; /* doesn't matter */
4478 fexpr->inputcollid = input_collid;
4479 fexpr->args = args;
4480 fexpr->location = -1;
4481
4482 pinfo = prepare_sql_fn_parse_info(func_tuple,
4483 (Node *) fexpr,
4484 input_collid);
4485
4486 /* fexpr also provides a convenient way to resolve a composite result */
4487 (void) get_expr_result_type((Node *) fexpr,
4488 NULL,
4489 &rettupdesc);
4490
4491 /*
4492 * We just do parsing and parse analysis, not rewriting, because rewriting
4493 * will not affect table-free-SELECT-only queries, which is all that we
4494 * care about. Also, we can punt as soon as we detect more than one
4495 * command in the function body.
4496 */
4497 raw_parsetree_list = pg_parse_query(src);
4498 if (list_length(raw_parsetree_list) != 1)
4499 goto fail;
4500
4501 pstate = make_parsestate(NULL);
4502 pstate->p_sourcetext = src;
4503 sql_fn_parser_setup(pstate, pinfo);
4504
4505 querytree = transformTopLevelStmt(pstate, linitial(raw_parsetree_list));
4506
4507 free_parsestate(pstate);
4508
4509 /*
4510 * The single command must be a simple "SELECT expression".
4511 *
4512 * Note: if you change the tests involved in this, see also plpgsql's
4513 * exec_simple_check_plan(). That generally needs to have the same idea
4514 * of what's a "simple expression", so that inlining a function that
4515 * previously wasn't inlined won't change plpgsql's conclusion.
4516 */
4517 if (!IsA(querytree, Query) ||
4518 querytree->commandType != CMD_SELECT ||
4519 querytree->hasAggs ||
4520 querytree->hasWindowFuncs ||
4521 querytree->hasTargetSRFs ||
4522 querytree->hasSubLinks ||
4523 querytree->cteList ||
4524 querytree->rtable ||
4525 querytree->jointree->fromlist ||
4526 querytree->jointree->quals ||
4527 querytree->groupClause ||
4528 querytree->groupingSets ||
4529 querytree->havingQual ||
4530 querytree->windowClause ||
4531 querytree->distinctClause ||
4532 querytree->sortClause ||
4533 querytree->limitOffset ||
4534 querytree->limitCount ||
4535 querytree->setOperations ||
4536 list_length(querytree->targetList) != 1)
4537 goto fail;
4538
4539 /*
4540 * Make sure the function (still) returns what it's declared to. This
4541 * will raise an error if wrong, but that's okay since the function would
4542 * fail at runtime anyway. Note that check_sql_fn_retval will also insert
4543 * a coercion if needed to make the tlist expression match the declared
4544 * type of the function.
4545 *
4546 * Note: we do not try this until we have verified that no rewriting was
4547 * needed; that's probably not important, but let's be careful.
4548 */
4549 querytree_list = list_make1(querytree);
4550 if (check_sql_fn_retval(list_make1(querytree_list),
4551 result_type, rettupdesc,
4552 false, NULL))
4553 goto fail; /* reject whole-tuple-result cases */
4554
4555 /*
4556 * Given the tests above, check_sql_fn_retval shouldn't have decided to
4557 * inject a projection step, but let's just make sure.
4558 */
4559 if (querytree != linitial(querytree_list))
4560 goto fail;
4561
4562 /* Now we can grab the tlist expression */
4563 newexpr = (Node *) ((TargetEntry *) linitial(querytree->targetList))->expr;
4564
4565 /*
4566 * If the SQL function returns VOID, we can only inline it if it is a
4567 * SELECT of an expression returning VOID (ie, it's just a redirection to
4568 * another VOID-returning function). In all non-VOID-returning cases,
4569 * check_sql_fn_retval should ensure that newexpr returns the function's
4570 * declared result type, so this test shouldn't fail otherwise; but we may
4571 * as well cope gracefully if it does.
4572 */
4573 if (exprType(newexpr) != result_type)
4574 goto fail;
4575
4576 /*
4577 * Additional validity checks on the expression. It mustn't be more
4578 * volatile than the surrounding function (this is to avoid breaking hacks
4579 * that involve pretending a function is immutable when it really ain't).
4580 * If the surrounding function is declared strict, then the expression
4581 * must contain only strict constructs and must use all of the function
4582 * parameters (this is overkill, but an exact analysis is hard).
4583 */
4584 if (funcform->provolatile == PROVOLATILE_IMMUTABLE &&
4585 contain_mutable_functions(newexpr))
4586 goto fail;
4587 else if (funcform->provolatile == PROVOLATILE_STABLE &&
4588 contain_volatile_functions(newexpr))
4589 goto fail;
4590
4591 if (funcform->proisstrict &&
4592 contain_nonstrict_functions(newexpr))
4593 goto fail;
4594
4595 /*
4596 * If any parameter expression contains a context-dependent node, we can't
4597 * inline, for fear of putting such a node into the wrong context.
4598 */
4599 if (contain_context_dependent_node((Node *) args))
4600 goto fail;
4601
4602 /*
4603 * We may be able to do it; there are still checks on parameter usage to
4604 * make, but those are most easily done in combination with the actual
4605 * substitution of the inputs. So start building expression with inputs
4606 * substituted.
4607 */
4608 usecounts = (int *) palloc0(funcform->pronargs * sizeof(int));
4609 newexpr = substitute_actual_parameters(newexpr, funcform->pronargs,
4610 args, usecounts);
4611
4612 /* Now check for parameter usage */
4613 i = 0;
4614 foreach(arg, args)
4615 {
4616 Node *param = lfirst(arg);
4617
4618 if (usecounts[i] == 0)
4619 {
4620 /* Param not used at all: uncool if func is strict */
4621 if (funcform->proisstrict)
4622 goto fail;
4623 }
4624 else if (usecounts[i] != 1)
4625 {
4626 /* Param used multiple times: uncool if expensive or volatile */
4627 QualCost eval_cost;
4628
4629 /*
4630 * We define "expensive" as "contains any subplan or more than 10
4631 * operators". Note that the subplan search has to be done
4632 * explicitly, since cost_qual_eval() will barf on unplanned
4633 * subselects.
4634 */
4635 if (contain_subplans(param))
4636 goto fail;
4637 cost_qual_eval(&eval_cost, list_make1(param), NULL);
4638 if (eval_cost.startup + eval_cost.per_tuple >
4639 10 * cpu_operator_cost)
4640 goto fail;
4641
4642 /*
4643 * Check volatility last since this is more expensive than the
4644 * above tests
4645 */
4646 if (contain_volatile_functions(param))
4647 goto fail;
4648 }
4649 i++;
4650 }
4651
4652 /*
4653 * Whew --- we can make the substitution. Copy the modified expression
4654 * out of the temporary memory context, and clean up.
4655 */
4656 MemoryContextSwitchTo(oldcxt);
4657
4658 newexpr = copyObject(newexpr);
4659
4660 MemoryContextDelete(mycxt);
4661
4662 /*
4663 * If the result is of a collatable type, force the result to expose the
4664 * correct collation. In most cases this does not matter, but it's
4665 * possible that the function result is used directly as a sort key or in
4666 * other places where we expect exprCollation() to tell the truth.
4667 */
4668 if (OidIsValid(result_collid))
4669 {
4670 Oid exprcoll = exprCollation(newexpr);
4671
4672 if (OidIsValid(exprcoll) && exprcoll != result_collid)
4673 {
4674 CollateExpr *newnode = makeNode(CollateExpr);
4675
4676 newnode->arg = (Expr *) newexpr;
4677 newnode->collOid = result_collid;
4678 newnode->location = -1;
4679
4680 newexpr = (Node *) newnode;
4681 }
4682 }
4683
4684 /*
4685 * Since there is now no trace of the function in the plan tree, we must
4686 * explicitly record the plan's dependency on the function.
4687 */
4688 if (context->root)
4689 record_plan_function_dependency(context->root, funcid);
4690
4691 /*
4692 * Recursively try to simplify the modified expression. Here we must add
4693 * the current function to the context list of active functions.
4694 */
4695 context->active_fns = lappend_oid(context->active_fns, funcid);
4696 newexpr = eval_const_expressions_mutator(newexpr, context);
4697 context->active_fns = list_delete_last(context->active_fns);
4698
4699 error_context_stack = sqlerrcontext.previous;
4700
4701 return (Expr *) newexpr;
4702
4703 /* Here if func is not inlinable: release temp memory and return NULL */
4704 fail:
4705 MemoryContextSwitchTo(oldcxt);
4706 MemoryContextDelete(mycxt);
4707 error_context_stack = sqlerrcontext.previous;
4708
4709 return NULL;
4710 }
4711
4712 /*
4713 * Replace Param nodes by appropriate actual parameters
4714 */
4715 static Node *
substitute_actual_parameters(Node * expr,int nargs,List * args,int * usecounts)4716 substitute_actual_parameters(Node *expr, int nargs, List *args,
4717 int *usecounts)
4718 {
4719 substitute_actual_parameters_context context;
4720
4721 context.nargs = nargs;
4722 context.args = args;
4723 context.usecounts = usecounts;
4724
4725 return substitute_actual_parameters_mutator(expr, &context);
4726 }
4727
4728 static Node *
substitute_actual_parameters_mutator(Node * node,substitute_actual_parameters_context * context)4729 substitute_actual_parameters_mutator(Node *node,
4730 substitute_actual_parameters_context *context)
4731 {
4732 if (node == NULL)
4733 return NULL;
4734 if (IsA(node, Param))
4735 {
4736 Param *param = (Param *) node;
4737
4738 if (param->paramkind != PARAM_EXTERN)
4739 elog(ERROR, "unexpected paramkind: %d", (int) param->paramkind);
4740 if (param->paramid <= 0 || param->paramid > context->nargs)
4741 elog(ERROR, "invalid paramid: %d", param->paramid);
4742
4743 /* Count usage of parameter */
4744 context->usecounts[param->paramid - 1]++;
4745
4746 /* Select the appropriate actual arg and replace the Param with it */
4747 /* We don't need to copy at this time (it'll get done later) */
4748 return list_nth(context->args, param->paramid - 1);
4749 }
4750 return expression_tree_mutator(node, substitute_actual_parameters_mutator,
4751 (void *) context);
4752 }
4753
4754 /*
4755 * error context callback to let us supply a call-stack traceback
4756 */
4757 static void
sql_inline_error_callback(void * arg)4758 sql_inline_error_callback(void *arg)
4759 {
4760 inline_error_callback_arg *callback_arg = (inline_error_callback_arg *) arg;
4761 int syntaxerrposition;
4762
4763 /* If it's a syntax error, convert to internal syntax error report */
4764 syntaxerrposition = geterrposition();
4765 if (syntaxerrposition > 0)
4766 {
4767 errposition(0);
4768 internalerrposition(syntaxerrposition);
4769 internalerrquery(callback_arg->prosrc);
4770 }
4771
4772 errcontext("SQL function \"%s\" during inlining", callback_arg->proname);
4773 }
4774
4775 /*
4776 * evaluate_expr: pre-evaluate a constant expression
4777 *
4778 * We use the executor's routine ExecEvalExpr() to avoid duplication of
4779 * code and ensure we get the same result as the executor would get.
4780 */
4781 Expr *
evaluate_expr(Expr * expr,Oid result_type,int32 result_typmod,Oid result_collation)4782 evaluate_expr(Expr *expr, Oid result_type, int32 result_typmod,
4783 Oid result_collation)
4784 {
4785 EState *estate;
4786 ExprState *exprstate;
4787 MemoryContext oldcontext;
4788 Datum const_val;
4789 bool const_is_null;
4790 int16 resultTypLen;
4791 bool resultTypByVal;
4792
4793 /*
4794 * To use the executor, we need an EState.
4795 */
4796 estate = CreateExecutorState();
4797
4798 /* We can use the estate's working context to avoid memory leaks. */
4799 oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
4800
4801 /* Make sure any opfuncids are filled in. */
4802 fix_opfuncids((Node *) expr);
4803
4804 /*
4805 * Prepare expr for execution. (Note: we can't use ExecPrepareExpr
4806 * because it'd result in recursively invoking eval_const_expressions.)
4807 */
4808 exprstate = ExecInitExpr(expr, NULL);
4809
4810 /*
4811 * And evaluate it.
4812 *
4813 * It is OK to use a default econtext because none of the ExecEvalExpr()
4814 * code used in this situation will use econtext. That might seem
4815 * fortuitous, but it's not so unreasonable --- a constant expression does
4816 * not depend on context, by definition, n'est ce pas?
4817 */
4818 const_val = ExecEvalExprSwitchContext(exprstate,
4819 GetPerTupleExprContext(estate),
4820 &const_is_null);
4821
4822 /* Get info needed about result datatype */
4823 get_typlenbyval(result_type, &resultTypLen, &resultTypByVal);
4824
4825 /* Get back to outer memory context */
4826 MemoryContextSwitchTo(oldcontext);
4827
4828 /*
4829 * Must copy result out of sub-context used by expression eval.
4830 *
4831 * Also, if it's varlena, forcibly detoast it. This protects us against
4832 * storing TOAST pointers into plans that might outlive the referenced
4833 * data. (makeConst would handle detoasting anyway, but it's worth a few
4834 * extra lines here so that we can do the copy and detoast in one step.)
4835 */
4836 if (!const_is_null)
4837 {
4838 if (resultTypLen == -1)
4839 const_val = PointerGetDatum(PG_DETOAST_DATUM_COPY(const_val));
4840 else
4841 const_val = datumCopy(const_val, resultTypByVal, resultTypLen);
4842 }
4843
4844 /* Release all the junk we just created */
4845 FreeExecutorState(estate);
4846
4847 /*
4848 * Make the constant result node.
4849 */
4850 return (Expr *) makeConst(result_type, result_typmod, result_collation,
4851 resultTypLen,
4852 const_val, const_is_null,
4853 resultTypByVal);
4854 }
4855
4856
4857 /*
4858 * inline_set_returning_function
4859 * Attempt to "inline" a set-returning function in the FROM clause.
4860 *
4861 * "rte" is an RTE_FUNCTION rangetable entry. If it represents a call of a
4862 * set-returning SQL function that can safely be inlined, expand the function
4863 * and return the substitute Query structure. Otherwise, return NULL.
4864 *
4865 * We assume that the RTE's expression has already been put through
4866 * eval_const_expressions(), which among other things will take care of
4867 * default arguments and named-argument notation.
4868 *
4869 * This has a good deal of similarity to inline_function(), but that's
4870 * for the non-set-returning case, and there are enough differences to
4871 * justify separate functions.
4872 */
4873 Query *
inline_set_returning_function(PlannerInfo * root,RangeTblEntry * rte)4874 inline_set_returning_function(PlannerInfo *root, RangeTblEntry *rte)
4875 {
4876 RangeTblFunction *rtfunc;
4877 FuncExpr *fexpr;
4878 Oid func_oid;
4879 HeapTuple func_tuple;
4880 Form_pg_proc funcform;
4881 char *src;
4882 Datum tmp;
4883 bool isNull;
4884 MemoryContext oldcxt;
4885 MemoryContext mycxt;
4886 inline_error_callback_arg callback_arg;
4887 ErrorContextCallback sqlerrcontext;
4888 SQLFunctionParseInfoPtr pinfo;
4889 TypeFuncClass functypclass;
4890 TupleDesc rettupdesc;
4891 List *raw_parsetree_list;
4892 List *querytree_list;
4893 Query *querytree;
4894
4895 Assert(rte->rtekind == RTE_FUNCTION);
4896
4897 /*
4898 * It doesn't make a lot of sense for a SQL SRF to refer to itself in its
4899 * own FROM clause, since that must cause infinite recursion at runtime.
4900 * It will cause this code to recurse too, so check for stack overflow.
4901 * (There's no need to do more.)
4902 */
4903 check_stack_depth();
4904
4905 /* Fail if the RTE has ORDINALITY - we don't implement that here. */
4906 if (rte->funcordinality)
4907 return NULL;
4908
4909 /* Fail if RTE isn't a single, simple FuncExpr */
4910 if (list_length(rte->functions) != 1)
4911 return NULL;
4912 rtfunc = (RangeTblFunction *) linitial(rte->functions);
4913
4914 if (!IsA(rtfunc->funcexpr, FuncExpr))
4915 return NULL;
4916 fexpr = (FuncExpr *) rtfunc->funcexpr;
4917
4918 func_oid = fexpr->funcid;
4919
4920 /*
4921 * The function must be declared to return a set, else inlining would
4922 * change the results if the contained SELECT didn't return exactly one
4923 * row.
4924 */
4925 if (!fexpr->funcretset)
4926 return NULL;
4927
4928 /*
4929 * Refuse to inline if the arguments contain any volatile functions or
4930 * sub-selects. Volatile functions are rejected because inlining may
4931 * result in the arguments being evaluated multiple times, risking a
4932 * change in behavior. Sub-selects are rejected partly for implementation
4933 * reasons (pushing them down another level might change their behavior)
4934 * and partly because they're likely to be expensive and so multiple
4935 * evaluation would be bad.
4936 */
4937 if (contain_volatile_functions((Node *) fexpr->args) ||
4938 contain_subplans((Node *) fexpr->args))
4939 return NULL;
4940
4941 /* Check permission to call function (fail later, if not) */
4942 if (pg_proc_aclcheck(func_oid, GetUserId(), ACL_EXECUTE) != ACLCHECK_OK)
4943 return NULL;
4944
4945 /* Check whether a plugin wants to hook function entry/exit */
4946 if (FmgrHookIsNeeded(func_oid))
4947 return NULL;
4948
4949 /*
4950 * OK, let's take a look at the function's pg_proc entry.
4951 */
4952 func_tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(func_oid));
4953 if (!HeapTupleIsValid(func_tuple))
4954 elog(ERROR, "cache lookup failed for function %u", func_oid);
4955 funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
4956
4957 /*
4958 * Forget it if the function is not SQL-language or has other showstopper
4959 * properties. In particular it mustn't be declared STRICT, since we
4960 * couldn't enforce that. It also mustn't be VOLATILE, because that is
4961 * supposed to cause it to be executed with its own snapshot, rather than
4962 * sharing the snapshot of the calling query. We also disallow returning
4963 * SETOF VOID, because inlining would result in exposing the actual result
4964 * of the function's last SELECT, which should not happen in that case.
4965 * (Rechecking prokind, proretset, and pronargs is just paranoia.)
4966 */
4967 if (funcform->prolang != SQLlanguageId ||
4968 funcform->prokind != PROKIND_FUNCTION ||
4969 funcform->proisstrict ||
4970 funcform->provolatile == PROVOLATILE_VOLATILE ||
4971 funcform->prorettype == VOIDOID ||
4972 funcform->prosecdef ||
4973 !funcform->proretset ||
4974 list_length(fexpr->args) != funcform->pronargs ||
4975 !heap_attisnull(func_tuple, Anum_pg_proc_proconfig, NULL))
4976 {
4977 ReleaseSysCache(func_tuple);
4978 return NULL;
4979 }
4980
4981 /*
4982 * Make a temporary memory context, so that we don't leak all the stuff
4983 * that parsing might create.
4984 */
4985 mycxt = AllocSetContextCreate(CurrentMemoryContext,
4986 "inline_set_returning_function",
4987 ALLOCSET_DEFAULT_SIZES);
4988 oldcxt = MemoryContextSwitchTo(mycxt);
4989
4990 /* Fetch the function body */
4991 tmp = SysCacheGetAttr(PROCOID,
4992 func_tuple,
4993 Anum_pg_proc_prosrc,
4994 &isNull);
4995 if (isNull)
4996 elog(ERROR, "null prosrc for function %u", func_oid);
4997 src = TextDatumGetCString(tmp);
4998
4999 /*
5000 * Setup error traceback support for ereport(). This is so that we can
5001 * finger the function that bad information came from.
5002 */
5003 callback_arg.proname = NameStr(funcform->proname);
5004 callback_arg.prosrc = src;
5005
5006 sqlerrcontext.callback = sql_inline_error_callback;
5007 sqlerrcontext.arg = (void *) &callback_arg;
5008 sqlerrcontext.previous = error_context_stack;
5009 error_context_stack = &sqlerrcontext;
5010
5011 /*
5012 * Set up to handle parameters while parsing the function body. We can
5013 * use the FuncExpr just created as the input for
5014 * prepare_sql_fn_parse_info.
5015 */
5016 pinfo = prepare_sql_fn_parse_info(func_tuple,
5017 (Node *) fexpr,
5018 fexpr->inputcollid);
5019
5020 /*
5021 * Also resolve the actual function result tupdesc, if composite. If the
5022 * function is just declared to return RECORD, dig the info out of the AS
5023 * clause.
5024 */
5025 functypclass = get_expr_result_type((Node *) fexpr, NULL, &rettupdesc);
5026 if (functypclass == TYPEFUNC_RECORD)
5027 rettupdesc = BuildDescFromLists(rtfunc->funccolnames,
5028 rtfunc->funccoltypes,
5029 rtfunc->funccoltypmods,
5030 rtfunc->funccolcollations);
5031
5032 /*
5033 * Parse, analyze, and rewrite (unlike inline_function(), we can't skip
5034 * rewriting here). We can fail as soon as we find more than one query,
5035 * though.
5036 */
5037 raw_parsetree_list = pg_parse_query(src);
5038 if (list_length(raw_parsetree_list) != 1)
5039 goto fail;
5040
5041 querytree_list = pg_analyze_and_rewrite_params(linitial(raw_parsetree_list),
5042 src,
5043 (ParserSetupHook) sql_fn_parser_setup,
5044 pinfo, NULL);
5045 if (list_length(querytree_list) != 1)
5046 goto fail;
5047 querytree = linitial(querytree_list);
5048
5049 /*
5050 * The single command must be a plain SELECT.
5051 */
5052 if (!IsA(querytree, Query) ||
5053 querytree->commandType != CMD_SELECT)
5054 goto fail;
5055
5056 /*
5057 * Make sure the function (still) returns what it's declared to. This
5058 * will raise an error if wrong, but that's okay since the function would
5059 * fail at runtime anyway. Note that check_sql_fn_retval will also insert
5060 * coercions if needed to make the tlist expression(s) match the declared
5061 * type of the function. We also ask it to insert dummy NULL columns for
5062 * any dropped columns in rettupdesc, so that the elements of the modified
5063 * tlist match up to the attribute numbers.
5064 *
5065 * If the function returns a composite type, don't inline unless the check
5066 * shows it's returning a whole tuple result; otherwise what it's
5067 * returning is a single composite column which is not what we need.
5068 */
5069 if (!check_sql_fn_retval(list_make1(querytree_list),
5070 fexpr->funcresulttype, rettupdesc,
5071 true, NULL) &&
5072 (functypclass == TYPEFUNC_COMPOSITE ||
5073 functypclass == TYPEFUNC_COMPOSITE_DOMAIN ||
5074 functypclass == TYPEFUNC_RECORD))
5075 goto fail; /* reject not-whole-tuple-result cases */
5076
5077 /*
5078 * check_sql_fn_retval might've inserted a projection step, but that's
5079 * fine; just make sure we use the upper Query.
5080 */
5081 querytree = linitial_node(Query, querytree_list);
5082
5083 /*
5084 * Looks good --- substitute parameters into the query.
5085 */
5086 querytree = substitute_actual_srf_parameters(querytree,
5087 funcform->pronargs,
5088 fexpr->args);
5089
5090 /*
5091 * Copy the modified query out of the temporary memory context, and clean
5092 * up.
5093 */
5094 MemoryContextSwitchTo(oldcxt);
5095
5096 querytree = copyObject(querytree);
5097
5098 MemoryContextDelete(mycxt);
5099 error_context_stack = sqlerrcontext.previous;
5100 ReleaseSysCache(func_tuple);
5101
5102 /*
5103 * We don't have to fix collations here because the upper query is already
5104 * parsed, ie, the collations in the RTE are what count.
5105 */
5106
5107 /*
5108 * Since there is now no trace of the function in the plan tree, we must
5109 * explicitly record the plan's dependency on the function.
5110 */
5111 record_plan_function_dependency(root, func_oid);
5112
5113 return querytree;
5114
5115 /* Here if func is not inlinable: release temp memory and return NULL */
5116 fail:
5117 MemoryContextSwitchTo(oldcxt);
5118 MemoryContextDelete(mycxt);
5119 error_context_stack = sqlerrcontext.previous;
5120 ReleaseSysCache(func_tuple);
5121
5122 return NULL;
5123 }
5124
5125 /*
5126 * Replace Param nodes by appropriate actual parameters
5127 *
5128 * This is just enough different from substitute_actual_parameters()
5129 * that it needs its own code.
5130 */
5131 static Query *
substitute_actual_srf_parameters(Query * expr,int nargs,List * args)5132 substitute_actual_srf_parameters(Query *expr, int nargs, List *args)
5133 {
5134 substitute_actual_srf_parameters_context context;
5135
5136 context.nargs = nargs;
5137 context.args = args;
5138 context.sublevels_up = 1;
5139
5140 return query_tree_mutator(expr,
5141 substitute_actual_srf_parameters_mutator,
5142 &context,
5143 0);
5144 }
5145
5146 static Node *
substitute_actual_srf_parameters_mutator(Node * node,substitute_actual_srf_parameters_context * context)5147 substitute_actual_srf_parameters_mutator(Node *node,
5148 substitute_actual_srf_parameters_context *context)
5149 {
5150 Node *result;
5151
5152 if (node == NULL)
5153 return NULL;
5154 if (IsA(node, Query))
5155 {
5156 context->sublevels_up++;
5157 result = (Node *) query_tree_mutator((Query *) node,
5158 substitute_actual_srf_parameters_mutator,
5159 (void *) context,
5160 0);
5161 context->sublevels_up--;
5162 return result;
5163 }
5164 if (IsA(node, Param))
5165 {
5166 Param *param = (Param *) node;
5167
5168 if (param->paramkind == PARAM_EXTERN)
5169 {
5170 if (param->paramid <= 0 || param->paramid > context->nargs)
5171 elog(ERROR, "invalid paramid: %d", param->paramid);
5172
5173 /*
5174 * Since the parameter is being inserted into a subquery, we must
5175 * adjust levels.
5176 */
5177 result = copyObject(list_nth(context->args, param->paramid - 1));
5178 IncrementVarSublevelsUp(result, context->sublevels_up, 0);
5179 return result;
5180 }
5181 }
5182 return expression_tree_mutator(node,
5183 substitute_actual_srf_parameters_mutator,
5184 (void *) context);
5185 }
5186