1 /*-------------------------------------------------------------------------
2 *
3 * deparse.c
4 * Query deparser for postgres_fdw
5 *
6 * This file includes functions that examine query WHERE clauses to see
7 * whether they're safe to send to the remote server for execution, as
8 * well as functions to construct the query text to be sent. The latter
9 * functionality is annoyingly duplicative of ruleutils.c, but there are
10 * enough special considerations that it seems best to keep this separate.
11 * One saving grace is that we only need deparse logic for node types that
12 * we consider safe to send.
13 *
14 * We assume that the remote session's search_path is exactly "pg_catalog",
15 * and thus we need schema-qualify all and only names outside pg_catalog.
16 *
17 * We do not consider that it is ever safe to send COLLATE expressions to
18 * the remote server: it might not have the same collation names we do.
19 * (Later we might consider it safe to send COLLATE "C", but even that would
20 * fail on old remote servers.) An expression is considered safe to send
21 * only if all operator/function input collations used in it are traceable to
22 * Var(s) of the foreign table. That implies that if the remote server gets
23 * a different answer than we do, the foreign table's columns are not marked
24 * with collations that match the remote table's columns, which we can
25 * consider to be user error.
26 *
27 * Portions Copyright (c) 2012-2021, PostgreSQL Global Development Group
28 *
29 * IDENTIFICATION
30 * contrib/postgres_fdw/deparse.c
31 *
32 *-------------------------------------------------------------------------
33 */
34 #include "postgres.h"
35
36 #include "access/htup_details.h"
37 #include "access/sysattr.h"
38 #include "access/table.h"
39 #include "catalog/pg_aggregate.h"
40 #include "catalog/pg_collation.h"
41 #include "catalog/pg_namespace.h"
42 #include "catalog/pg_operator.h"
43 #include "catalog/pg_proc.h"
44 #include "catalog/pg_type.h"
45 #include "commands/defrem.h"
46 #include "nodes/makefuncs.h"
47 #include "nodes/nodeFuncs.h"
48 #include "nodes/plannodes.h"
49 #include "optimizer/optimizer.h"
50 #include "optimizer/prep.h"
51 #include "optimizer/tlist.h"
52 #include "parser/parsetree.h"
53 #include "postgres_fdw.h"
54 #include "utils/builtins.h"
55 #include "utils/lsyscache.h"
56 #include "utils/rel.h"
57 #include "utils/syscache.h"
58 #include "utils/typcache.h"
59 #include "commands/tablecmds.h"
60
61 /*
62 * Global context for foreign_expr_walker's search of an expression tree.
63 */
64 typedef struct foreign_glob_cxt
65 {
66 PlannerInfo *root; /* global planner state */
67 RelOptInfo *foreignrel; /* the foreign relation we are planning for */
68 Relids relids; /* relids of base relations in the underlying
69 * scan */
70 } foreign_glob_cxt;
71
72 /*
73 * Local (per-tree-level) context for foreign_expr_walker's search.
74 * This is concerned with identifying collations used in the expression.
75 */
76 typedef enum
77 {
78 FDW_COLLATE_NONE, /* expression is of a noncollatable type, or
79 * it has default collation that is not
80 * traceable to a foreign Var */
81 FDW_COLLATE_SAFE, /* collation derives from a foreign Var */
82 FDW_COLLATE_UNSAFE /* collation is non-default and derives from
83 * something other than a foreign Var */
84 } FDWCollateState;
85
86 typedef struct foreign_loc_cxt
87 {
88 Oid collation; /* OID of current collation, if any */
89 FDWCollateState state; /* state of current collation choice */
90 } foreign_loc_cxt;
91
92 /*
93 * Context for deparseExpr
94 */
95 typedef struct deparse_expr_cxt
96 {
97 PlannerInfo *root; /* global planner state */
98 RelOptInfo *foreignrel; /* the foreign relation we are planning for */
99 RelOptInfo *scanrel; /* the underlying scan relation. Same as
100 * foreignrel, when that represents a join or
101 * a base relation. */
102 StringInfo buf; /* output buffer to append to */
103 List **params_list; /* exprs that will become remote Params */
104 } deparse_expr_cxt;
105
106 #define REL_ALIAS_PREFIX "r"
107 /* Handy macro to add relation name qualification */
108 #define ADD_REL_QUALIFIER(buf, varno) \
109 appendStringInfo((buf), "%s%d.", REL_ALIAS_PREFIX, (varno))
110 #define SUBQUERY_REL_ALIAS_PREFIX "s"
111 #define SUBQUERY_COL_ALIAS_PREFIX "c"
112
113 /*
114 * Functions to determine whether an expression can be evaluated safely on
115 * remote server.
116 */
117 static bool foreign_expr_walker(Node *node,
118 foreign_glob_cxt *glob_cxt,
119 foreign_loc_cxt *outer_cxt);
120 static char *deparse_type_name(Oid type_oid, int32 typemod);
121
122 /*
123 * Functions to construct string representation of a node tree.
124 */
125 static void deparseTargetList(StringInfo buf,
126 RangeTblEntry *rte,
127 Index rtindex,
128 Relation rel,
129 bool is_returning,
130 Bitmapset *attrs_used,
131 bool qualify_col,
132 List **retrieved_attrs);
133 static void deparseExplicitTargetList(List *tlist,
134 bool is_returning,
135 List **retrieved_attrs,
136 deparse_expr_cxt *context);
137 static void deparseSubqueryTargetList(deparse_expr_cxt *context);
138 static void deparseReturningList(StringInfo buf, RangeTblEntry *rte,
139 Index rtindex, Relation rel,
140 bool trig_after_row,
141 List *withCheckOptionList,
142 List *returningList,
143 List **retrieved_attrs);
144 static void deparseColumnRef(StringInfo buf, int varno, int varattno,
145 RangeTblEntry *rte, bool qualify_col);
146 static void deparseRelation(StringInfo buf, Relation rel);
147 static void deparseExpr(Expr *expr, deparse_expr_cxt *context);
148 static void deparseVar(Var *node, deparse_expr_cxt *context);
149 static void deparseConst(Const *node, deparse_expr_cxt *context, int showtype);
150 static void deparseParam(Param *node, deparse_expr_cxt *context);
151 static void deparseSubscriptingRef(SubscriptingRef *node, deparse_expr_cxt *context);
152 static void deparseFuncExpr(FuncExpr *node, deparse_expr_cxt *context);
153 static void deparseOpExpr(OpExpr *node, deparse_expr_cxt *context);
154 static void deparseOperatorName(StringInfo buf, Form_pg_operator opform);
155 static void deparseDistinctExpr(DistinctExpr *node, deparse_expr_cxt *context);
156 static void deparseScalarArrayOpExpr(ScalarArrayOpExpr *node,
157 deparse_expr_cxt *context);
158 static void deparseRelabelType(RelabelType *node, deparse_expr_cxt *context);
159 static void deparseBoolExpr(BoolExpr *node, deparse_expr_cxt *context);
160 static void deparseNullTest(NullTest *node, deparse_expr_cxt *context);
161 static void deparseArrayExpr(ArrayExpr *node, deparse_expr_cxt *context);
162 static void printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod,
163 deparse_expr_cxt *context);
164 static void printRemotePlaceholder(Oid paramtype, int32 paramtypmod,
165 deparse_expr_cxt *context);
166 static void deparseSelectSql(List *tlist, bool is_subquery, List **retrieved_attrs,
167 deparse_expr_cxt *context);
168 static void deparseLockingClause(deparse_expr_cxt *context);
169 static void appendOrderByClause(List *pathkeys, bool has_final_sort,
170 deparse_expr_cxt *context);
171 static void appendLimitClause(deparse_expr_cxt *context);
172 static void appendConditions(List *exprs, deparse_expr_cxt *context);
173 static void deparseFromExprForRel(StringInfo buf, PlannerInfo *root,
174 RelOptInfo *foreignrel, bool use_alias,
175 Index ignore_rel, List **ignore_conds,
176 List **params_list);
177 static void deparseFromExpr(List *quals, deparse_expr_cxt *context);
178 static void deparseRangeTblRef(StringInfo buf, PlannerInfo *root,
179 RelOptInfo *foreignrel, bool make_subquery,
180 Index ignore_rel, List **ignore_conds, List **params_list);
181 static void deparseAggref(Aggref *node, deparse_expr_cxt *context);
182 static void appendGroupByClause(List *tlist, deparse_expr_cxt *context);
183 static void appendAggOrderBy(List *orderList, List *targetList,
184 deparse_expr_cxt *context);
185 static void appendFunctionName(Oid funcid, deparse_expr_cxt *context);
186 static Node *deparseSortGroupClause(Index ref, List *tlist, bool force_colno,
187 deparse_expr_cxt *context);
188
189 /*
190 * Helper functions
191 */
192 static bool is_subquery_var(Var *node, RelOptInfo *foreignrel,
193 int *relno, int *colno);
194 static void get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
195 int *relno, int *colno);
196
197
198 /*
199 * Examine each qual clause in input_conds, and classify them into two groups,
200 * which are returned as two lists:
201 * - remote_conds contains expressions that can be evaluated remotely
202 * - local_conds contains expressions that can't be evaluated remotely
203 */
204 void
classifyConditions(PlannerInfo * root,RelOptInfo * baserel,List * input_conds,List ** remote_conds,List ** local_conds)205 classifyConditions(PlannerInfo *root,
206 RelOptInfo *baserel,
207 List *input_conds,
208 List **remote_conds,
209 List **local_conds)
210 {
211 ListCell *lc;
212
213 *remote_conds = NIL;
214 *local_conds = NIL;
215
216 foreach(lc, input_conds)
217 {
218 RestrictInfo *ri = lfirst_node(RestrictInfo, lc);
219
220 if (is_foreign_expr(root, baserel, ri->clause))
221 *remote_conds = lappend(*remote_conds, ri);
222 else
223 *local_conds = lappend(*local_conds, ri);
224 }
225 }
226
227 /*
228 * Returns true if given expr is safe to evaluate on the foreign server.
229 */
230 bool
is_foreign_expr(PlannerInfo * root,RelOptInfo * baserel,Expr * expr)231 is_foreign_expr(PlannerInfo *root,
232 RelOptInfo *baserel,
233 Expr *expr)
234 {
235 foreign_glob_cxt glob_cxt;
236 foreign_loc_cxt loc_cxt;
237 PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) (baserel->fdw_private);
238
239 /*
240 * Check that the expression consists of nodes that are safe to execute
241 * remotely.
242 */
243 glob_cxt.root = root;
244 glob_cxt.foreignrel = baserel;
245
246 /*
247 * For an upper relation, use relids from its underneath scan relation,
248 * because the upperrel's own relids currently aren't set to anything
249 * meaningful by the core code. For other relation, use their own relids.
250 */
251 if (IS_UPPER_REL(baserel))
252 glob_cxt.relids = fpinfo->outerrel->relids;
253 else
254 glob_cxt.relids = baserel->relids;
255 loc_cxt.collation = InvalidOid;
256 loc_cxt.state = FDW_COLLATE_NONE;
257 if (!foreign_expr_walker((Node *) expr, &glob_cxt, &loc_cxt))
258 return false;
259
260 /*
261 * If the expression has a valid collation that does not arise from a
262 * foreign var, the expression can not be sent over.
263 */
264 if (loc_cxt.state == FDW_COLLATE_UNSAFE)
265 return false;
266
267 /*
268 * An expression which includes any mutable functions can't be sent over
269 * because its result is not stable. For example, sending now() remote
270 * side could cause confusion from clock offsets. Future versions might
271 * be able to make this choice with more granularity. (We check this last
272 * because it requires a lot of expensive catalog lookups.)
273 */
274 if (contain_mutable_functions((Node *) expr))
275 return false;
276
277 /* OK to evaluate on the remote server */
278 return true;
279 }
280
281 /*
282 * Check if expression is safe to execute remotely, and return true if so.
283 *
284 * In addition, *outer_cxt is updated with collation information.
285 *
286 * We must check that the expression contains only node types we can deparse,
287 * that all types/functions/operators are safe to send (they are "shippable"),
288 * and that all collations used in the expression derive from Vars of the
289 * foreign table. Because of the latter, the logic is pretty close to
290 * assign_collations_walker() in parse_collate.c, though we can assume here
291 * that the given expression is valid. Note function mutability is not
292 * currently considered here.
293 */
294 static bool
foreign_expr_walker(Node * node,foreign_glob_cxt * glob_cxt,foreign_loc_cxt * outer_cxt)295 foreign_expr_walker(Node *node,
296 foreign_glob_cxt *glob_cxt,
297 foreign_loc_cxt *outer_cxt)
298 {
299 bool check_type = true;
300 PgFdwRelationInfo *fpinfo;
301 foreign_loc_cxt inner_cxt;
302 Oid collation;
303 FDWCollateState state;
304
305 /* Need do nothing for empty subexpressions */
306 if (node == NULL)
307 return true;
308
309 /* May need server info from baserel's fdw_private struct */
310 fpinfo = (PgFdwRelationInfo *) (glob_cxt->foreignrel->fdw_private);
311
312 /* Set up inner_cxt for possible recursion to child nodes */
313 inner_cxt.collation = InvalidOid;
314 inner_cxt.state = FDW_COLLATE_NONE;
315
316 switch (nodeTag(node))
317 {
318 case T_Var:
319 {
320 Var *var = (Var *) node;
321
322 /*
323 * If the Var is from the foreign table, we consider its
324 * collation (if any) safe to use. If it is from another
325 * table, we treat its collation the same way as we would a
326 * Param's collation, ie it's not safe for it to have a
327 * non-default collation.
328 */
329 if (bms_is_member(var->varno, glob_cxt->relids) &&
330 var->varlevelsup == 0)
331 {
332 /* Var belongs to foreign table */
333
334 /*
335 * System columns other than ctid should not be sent to
336 * the remote, since we don't make any effort to ensure
337 * that local and remote values match (tableoid, in
338 * particular, almost certainly doesn't match).
339 */
340 if (var->varattno < 0 &&
341 var->varattno != SelfItemPointerAttributeNumber)
342 return false;
343
344 /* Else check the collation */
345 collation = var->varcollid;
346 state = OidIsValid(collation) ? FDW_COLLATE_SAFE : FDW_COLLATE_NONE;
347 }
348 else
349 {
350 /* Var belongs to some other table */
351 collation = var->varcollid;
352 if (collation == InvalidOid ||
353 collation == DEFAULT_COLLATION_OID)
354 {
355 /*
356 * It's noncollatable, or it's safe to combine with a
357 * collatable foreign Var, so set state to NONE.
358 */
359 state = FDW_COLLATE_NONE;
360 }
361 else
362 {
363 /*
364 * Do not fail right away, since the Var might appear
365 * in a collation-insensitive context.
366 */
367 state = FDW_COLLATE_UNSAFE;
368 }
369 }
370 }
371 break;
372 case T_Const:
373 {
374 Const *c = (Const *) node;
375
376 /*
377 * If the constant has nondefault collation, either it's of a
378 * non-builtin type, or it reflects folding of a CollateExpr.
379 * It's unsafe to send to the remote unless it's used in a
380 * non-collation-sensitive context.
381 */
382 collation = c->constcollid;
383 if (collation == InvalidOid ||
384 collation == DEFAULT_COLLATION_OID)
385 state = FDW_COLLATE_NONE;
386 else
387 state = FDW_COLLATE_UNSAFE;
388 }
389 break;
390 case T_Param:
391 {
392 Param *p = (Param *) node;
393
394 /*
395 * If it's a MULTIEXPR Param, punt. We can't tell from here
396 * whether the referenced sublink/subplan contains any remote
397 * Vars; if it does, handling that is too complicated to
398 * consider supporting at present. Fortunately, MULTIEXPR
399 * Params are not reduced to plain PARAM_EXEC until the end of
400 * planning, so we can easily detect this case. (Normal
401 * PARAM_EXEC Params are safe to ship because their values
402 * come from somewhere else in the plan tree; but a MULTIEXPR
403 * references a sub-select elsewhere in the same targetlist,
404 * so we'd be on the hook to evaluate it somehow if we wanted
405 * to handle such cases as direct foreign updates.)
406 */
407 if (p->paramkind == PARAM_MULTIEXPR)
408 return false;
409
410 /*
411 * Collation rule is same as for Consts and non-foreign Vars.
412 */
413 collation = p->paramcollid;
414 if (collation == InvalidOid ||
415 collation == DEFAULT_COLLATION_OID)
416 state = FDW_COLLATE_NONE;
417 else
418 state = FDW_COLLATE_UNSAFE;
419 }
420 break;
421 case T_SubscriptingRef:
422 {
423 SubscriptingRef *sr = (SubscriptingRef *) node;
424
425 /* Assignment should not be in restrictions. */
426 if (sr->refassgnexpr != NULL)
427 return false;
428
429 /*
430 * Recurse into the remaining subexpressions. The container
431 * subscripts will not affect collation of the SubscriptingRef
432 * result, so do those first and reset inner_cxt afterwards.
433 */
434 if (!foreign_expr_walker((Node *) sr->refupperindexpr,
435 glob_cxt, &inner_cxt))
436 return false;
437 inner_cxt.collation = InvalidOid;
438 inner_cxt.state = FDW_COLLATE_NONE;
439 if (!foreign_expr_walker((Node *) sr->reflowerindexpr,
440 glob_cxt, &inner_cxt))
441 return false;
442 inner_cxt.collation = InvalidOid;
443 inner_cxt.state = FDW_COLLATE_NONE;
444 if (!foreign_expr_walker((Node *) sr->refexpr,
445 glob_cxt, &inner_cxt))
446 return false;
447
448 /*
449 * Container subscripting typically yields same collation as
450 * refexpr's, but in case it doesn't, use same logic as for
451 * function nodes.
452 */
453 collation = sr->refcollid;
454 if (collation == InvalidOid)
455 state = FDW_COLLATE_NONE;
456 else if (inner_cxt.state == FDW_COLLATE_SAFE &&
457 collation == inner_cxt.collation)
458 state = FDW_COLLATE_SAFE;
459 else if (collation == DEFAULT_COLLATION_OID)
460 state = FDW_COLLATE_NONE;
461 else
462 state = FDW_COLLATE_UNSAFE;
463 }
464 break;
465 case T_FuncExpr:
466 {
467 FuncExpr *fe = (FuncExpr *) node;
468
469 /*
470 * If function used by the expression is not shippable, it
471 * can't be sent to remote because it might have incompatible
472 * semantics on remote side.
473 */
474 if (!is_shippable(fe->funcid, ProcedureRelationId, fpinfo))
475 return false;
476
477 /*
478 * Recurse to input subexpressions.
479 */
480 if (!foreign_expr_walker((Node *) fe->args,
481 glob_cxt, &inner_cxt))
482 return false;
483
484 /*
485 * If function's input collation is not derived from a foreign
486 * Var, it can't be sent to remote.
487 */
488 if (fe->inputcollid == InvalidOid)
489 /* OK, inputs are all noncollatable */ ;
490 else if (inner_cxt.state != FDW_COLLATE_SAFE ||
491 fe->inputcollid != inner_cxt.collation)
492 return false;
493
494 /*
495 * Detect whether node is introducing a collation not derived
496 * from a foreign Var. (If so, we just mark it unsafe for now
497 * rather than immediately returning false, since the parent
498 * node might not care.)
499 */
500 collation = fe->funccollid;
501 if (collation == InvalidOid)
502 state = FDW_COLLATE_NONE;
503 else if (inner_cxt.state == FDW_COLLATE_SAFE &&
504 collation == inner_cxt.collation)
505 state = FDW_COLLATE_SAFE;
506 else if (collation == DEFAULT_COLLATION_OID)
507 state = FDW_COLLATE_NONE;
508 else
509 state = FDW_COLLATE_UNSAFE;
510 }
511 break;
512 case T_OpExpr:
513 case T_DistinctExpr: /* struct-equivalent to OpExpr */
514 {
515 OpExpr *oe = (OpExpr *) node;
516
517 /*
518 * Similarly, only shippable operators can be sent to remote.
519 * (If the operator is shippable, we assume its underlying
520 * function is too.)
521 */
522 if (!is_shippable(oe->opno, OperatorRelationId, fpinfo))
523 return false;
524
525 /*
526 * Recurse to input subexpressions.
527 */
528 if (!foreign_expr_walker((Node *) oe->args,
529 glob_cxt, &inner_cxt))
530 return false;
531
532 /*
533 * If operator's input collation is not derived from a foreign
534 * Var, it can't be sent to remote.
535 */
536 if (oe->inputcollid == InvalidOid)
537 /* OK, inputs are all noncollatable */ ;
538 else if (inner_cxt.state != FDW_COLLATE_SAFE ||
539 oe->inputcollid != inner_cxt.collation)
540 return false;
541
542 /* Result-collation handling is same as for functions */
543 collation = oe->opcollid;
544 if (collation == InvalidOid)
545 state = FDW_COLLATE_NONE;
546 else if (inner_cxt.state == FDW_COLLATE_SAFE &&
547 collation == inner_cxt.collation)
548 state = FDW_COLLATE_SAFE;
549 else if (collation == DEFAULT_COLLATION_OID)
550 state = FDW_COLLATE_NONE;
551 else
552 state = FDW_COLLATE_UNSAFE;
553 }
554 break;
555 case T_ScalarArrayOpExpr:
556 {
557 ScalarArrayOpExpr *oe = (ScalarArrayOpExpr *) node;
558
559 /*
560 * Again, only shippable operators can be sent to remote.
561 */
562 if (!is_shippable(oe->opno, OperatorRelationId, fpinfo))
563 return false;
564
565 /*
566 * Recurse to input subexpressions.
567 */
568 if (!foreign_expr_walker((Node *) oe->args,
569 glob_cxt, &inner_cxt))
570 return false;
571
572 /*
573 * If operator's input collation is not derived from a foreign
574 * Var, it can't be sent to remote.
575 */
576 if (oe->inputcollid == InvalidOid)
577 /* OK, inputs are all noncollatable */ ;
578 else if (inner_cxt.state != FDW_COLLATE_SAFE ||
579 oe->inputcollid != inner_cxt.collation)
580 return false;
581
582 /* Output is always boolean and so noncollatable. */
583 collation = InvalidOid;
584 state = FDW_COLLATE_NONE;
585 }
586 break;
587 case T_RelabelType:
588 {
589 RelabelType *r = (RelabelType *) node;
590
591 /*
592 * Recurse to input subexpression.
593 */
594 if (!foreign_expr_walker((Node *) r->arg,
595 glob_cxt, &inner_cxt))
596 return false;
597
598 /*
599 * RelabelType must not introduce a collation not derived from
600 * an input foreign Var (same logic as for a real function).
601 */
602 collation = r->resultcollid;
603 if (collation == InvalidOid)
604 state = FDW_COLLATE_NONE;
605 else if (inner_cxt.state == FDW_COLLATE_SAFE &&
606 collation == inner_cxt.collation)
607 state = FDW_COLLATE_SAFE;
608 else if (collation == DEFAULT_COLLATION_OID)
609 state = FDW_COLLATE_NONE;
610 else
611 state = FDW_COLLATE_UNSAFE;
612 }
613 break;
614 case T_BoolExpr:
615 {
616 BoolExpr *b = (BoolExpr *) node;
617
618 /*
619 * Recurse to input subexpressions.
620 */
621 if (!foreign_expr_walker((Node *) b->args,
622 glob_cxt, &inner_cxt))
623 return false;
624
625 /* Output is always boolean and so noncollatable. */
626 collation = InvalidOid;
627 state = FDW_COLLATE_NONE;
628 }
629 break;
630 case T_NullTest:
631 {
632 NullTest *nt = (NullTest *) node;
633
634 /*
635 * Recurse to input subexpressions.
636 */
637 if (!foreign_expr_walker((Node *) nt->arg,
638 glob_cxt, &inner_cxt))
639 return false;
640
641 /* Output is always boolean and so noncollatable. */
642 collation = InvalidOid;
643 state = FDW_COLLATE_NONE;
644 }
645 break;
646 case T_ArrayExpr:
647 {
648 ArrayExpr *a = (ArrayExpr *) node;
649
650 /*
651 * Recurse to input subexpressions.
652 */
653 if (!foreign_expr_walker((Node *) a->elements,
654 glob_cxt, &inner_cxt))
655 return false;
656
657 /*
658 * ArrayExpr must not introduce a collation not derived from
659 * an input foreign Var (same logic as for a function).
660 */
661 collation = a->array_collid;
662 if (collation == InvalidOid)
663 state = FDW_COLLATE_NONE;
664 else if (inner_cxt.state == FDW_COLLATE_SAFE &&
665 collation == inner_cxt.collation)
666 state = FDW_COLLATE_SAFE;
667 else if (collation == DEFAULT_COLLATION_OID)
668 state = FDW_COLLATE_NONE;
669 else
670 state = FDW_COLLATE_UNSAFE;
671 }
672 break;
673 case T_List:
674 {
675 List *l = (List *) node;
676 ListCell *lc;
677
678 /*
679 * Recurse to component subexpressions.
680 */
681 foreach(lc, l)
682 {
683 if (!foreign_expr_walker((Node *) lfirst(lc),
684 glob_cxt, &inner_cxt))
685 return false;
686 }
687
688 /*
689 * When processing a list, collation state just bubbles up
690 * from the list elements.
691 */
692 collation = inner_cxt.collation;
693 state = inner_cxt.state;
694
695 /* Don't apply exprType() to the list. */
696 check_type = false;
697 }
698 break;
699 case T_Aggref:
700 {
701 Aggref *agg = (Aggref *) node;
702 ListCell *lc;
703
704 /* Not safe to pushdown when not in grouping context */
705 if (!IS_UPPER_REL(glob_cxt->foreignrel))
706 return false;
707
708 /* Only non-split aggregates are pushable. */
709 if (agg->aggsplit != AGGSPLIT_SIMPLE)
710 return false;
711
712 /* As usual, it must be shippable. */
713 if (!is_shippable(agg->aggfnoid, ProcedureRelationId, fpinfo))
714 return false;
715
716 /*
717 * Recurse to input args. aggdirectargs, aggorder and
718 * aggdistinct are all present in args, so no need to check
719 * their shippability explicitly.
720 */
721 foreach(lc, agg->args)
722 {
723 Node *n = (Node *) lfirst(lc);
724
725 /* If TargetEntry, extract the expression from it */
726 if (IsA(n, TargetEntry))
727 {
728 TargetEntry *tle = (TargetEntry *) n;
729
730 n = (Node *) tle->expr;
731 }
732
733 if (!foreign_expr_walker(n, glob_cxt, &inner_cxt))
734 return false;
735 }
736
737 /*
738 * For aggorder elements, check whether the sort operator, if
739 * specified, is shippable or not.
740 */
741 if (agg->aggorder)
742 {
743 ListCell *lc;
744
745 foreach(lc, agg->aggorder)
746 {
747 SortGroupClause *srt = (SortGroupClause *) lfirst(lc);
748 Oid sortcoltype;
749 TypeCacheEntry *typentry;
750 TargetEntry *tle;
751
752 tle = get_sortgroupref_tle(srt->tleSortGroupRef,
753 agg->args);
754 sortcoltype = exprType((Node *) tle->expr);
755 typentry = lookup_type_cache(sortcoltype,
756 TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
757 /* Check shippability of non-default sort operator. */
758 if (srt->sortop != typentry->lt_opr &&
759 srt->sortop != typentry->gt_opr &&
760 !is_shippable(srt->sortop, OperatorRelationId,
761 fpinfo))
762 return false;
763 }
764 }
765
766 /* Check aggregate filter */
767 if (!foreign_expr_walker((Node *) agg->aggfilter,
768 glob_cxt, &inner_cxt))
769 return false;
770
771 /*
772 * If aggregate's input collation is not derived from a
773 * foreign Var, it can't be sent to remote.
774 */
775 if (agg->inputcollid == InvalidOid)
776 /* OK, inputs are all noncollatable */ ;
777 else if (inner_cxt.state != FDW_COLLATE_SAFE ||
778 agg->inputcollid != inner_cxt.collation)
779 return false;
780
781 /*
782 * Detect whether node is introducing a collation not derived
783 * from a foreign Var. (If so, we just mark it unsafe for now
784 * rather than immediately returning false, since the parent
785 * node might not care.)
786 */
787 collation = agg->aggcollid;
788 if (collation == InvalidOid)
789 state = FDW_COLLATE_NONE;
790 else if (inner_cxt.state == FDW_COLLATE_SAFE &&
791 collation == inner_cxt.collation)
792 state = FDW_COLLATE_SAFE;
793 else if (collation == DEFAULT_COLLATION_OID)
794 state = FDW_COLLATE_NONE;
795 else
796 state = FDW_COLLATE_UNSAFE;
797 }
798 break;
799 default:
800
801 /*
802 * If it's anything else, assume it's unsafe. This list can be
803 * expanded later, but don't forget to add deparse support below.
804 */
805 return false;
806 }
807
808 /*
809 * If result type of given expression is not shippable, it can't be sent
810 * to remote because it might have incompatible semantics on remote side.
811 */
812 if (check_type && !is_shippable(exprType(node), TypeRelationId, fpinfo))
813 return false;
814
815 /*
816 * Now, merge my collation information into my parent's state.
817 */
818 if (state > outer_cxt->state)
819 {
820 /* Override previous parent state */
821 outer_cxt->collation = collation;
822 outer_cxt->state = state;
823 }
824 else if (state == outer_cxt->state)
825 {
826 /* Merge, or detect error if there's a collation conflict */
827 switch (state)
828 {
829 case FDW_COLLATE_NONE:
830 /* Nothing + nothing is still nothing */
831 break;
832 case FDW_COLLATE_SAFE:
833 if (collation != outer_cxt->collation)
834 {
835 /*
836 * Non-default collation always beats default.
837 */
838 if (outer_cxt->collation == DEFAULT_COLLATION_OID)
839 {
840 /* Override previous parent state */
841 outer_cxt->collation = collation;
842 }
843 else if (collation != DEFAULT_COLLATION_OID)
844 {
845 /*
846 * Conflict; show state as indeterminate. We don't
847 * want to "return false" right away, since parent
848 * node might not care about collation.
849 */
850 outer_cxt->state = FDW_COLLATE_UNSAFE;
851 }
852 }
853 break;
854 case FDW_COLLATE_UNSAFE:
855 /* We're still conflicted ... */
856 break;
857 }
858 }
859
860 /* It looks OK */
861 return true;
862 }
863
864 /*
865 * Returns true if given expr is something we'd have to send the value of
866 * to the foreign server.
867 *
868 * This should return true when the expression is a shippable node that
869 * deparseExpr would add to context->params_list. Note that we don't care
870 * if the expression *contains* such a node, only whether one appears at top
871 * level. We need this to detect cases where setrefs.c would recognize a
872 * false match between an fdw_exprs item (which came from the params_list)
873 * and an entry in fdw_scan_tlist (which we're considering putting the given
874 * expression into).
875 */
876 bool
is_foreign_param(PlannerInfo * root,RelOptInfo * baserel,Expr * expr)877 is_foreign_param(PlannerInfo *root,
878 RelOptInfo *baserel,
879 Expr *expr)
880 {
881 if (expr == NULL)
882 return false;
883
884 switch (nodeTag(expr))
885 {
886 case T_Var:
887 {
888 /* It would have to be sent unless it's a foreign Var */
889 Var *var = (Var *) expr;
890 PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) (baserel->fdw_private);
891 Relids relids;
892
893 if (IS_UPPER_REL(baserel))
894 relids = fpinfo->outerrel->relids;
895 else
896 relids = baserel->relids;
897
898 if (bms_is_member(var->varno, relids) && var->varlevelsup == 0)
899 return false; /* foreign Var, so not a param */
900 else
901 return true; /* it'd have to be a param */
902 break;
903 }
904 case T_Param:
905 /* Params always have to be sent to the foreign server */
906 return true;
907 default:
908 break;
909 }
910 return false;
911 }
912
913 /*
914 * Convert type OID + typmod info into a type name we can ship to the remote
915 * server. Someplace else had better have verified that this type name is
916 * expected to be known on the remote end.
917 *
918 * This is almost just format_type_with_typemod(), except that if left to its
919 * own devices, that function will make schema-qualification decisions based
920 * on the local search_path, which is wrong. We must schema-qualify all
921 * type names that are not in pg_catalog. We assume here that built-in types
922 * are all in pg_catalog and need not be qualified; otherwise, qualify.
923 */
924 static char *
deparse_type_name(Oid type_oid,int32 typemod)925 deparse_type_name(Oid type_oid, int32 typemod)
926 {
927 bits16 flags = FORMAT_TYPE_TYPEMOD_GIVEN;
928
929 if (!is_builtin(type_oid))
930 flags |= FORMAT_TYPE_FORCE_QUALIFY;
931
932 return format_type_extended(type_oid, typemod, flags);
933 }
934
935 /*
936 * Build the targetlist for given relation to be deparsed as SELECT clause.
937 *
938 * The output targetlist contains the columns that need to be fetched from the
939 * foreign server for the given relation. If foreignrel is an upper relation,
940 * then the output targetlist can also contain expressions to be evaluated on
941 * foreign server.
942 */
943 List *
build_tlist_to_deparse(RelOptInfo * foreignrel)944 build_tlist_to_deparse(RelOptInfo *foreignrel)
945 {
946 List *tlist = NIL;
947 PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
948 ListCell *lc;
949
950 /*
951 * For an upper relation, we have already built the target list while
952 * checking shippability, so just return that.
953 */
954 if (IS_UPPER_REL(foreignrel))
955 return fpinfo->grouped_tlist;
956
957 /*
958 * We require columns specified in foreignrel->reltarget->exprs and those
959 * required for evaluating the local conditions.
960 */
961 tlist = add_to_flat_tlist(tlist,
962 pull_var_clause((Node *) foreignrel->reltarget->exprs,
963 PVC_RECURSE_PLACEHOLDERS));
964 foreach(lc, fpinfo->local_conds)
965 {
966 RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
967
968 tlist = add_to_flat_tlist(tlist,
969 pull_var_clause((Node *) rinfo->clause,
970 PVC_RECURSE_PLACEHOLDERS));
971 }
972
973 return tlist;
974 }
975
976 /*
977 * Deparse SELECT statement for given relation into buf.
978 *
979 * tlist contains the list of desired columns to be fetched from foreign server.
980 * For a base relation fpinfo->attrs_used is used to construct SELECT clause,
981 * hence the tlist is ignored for a base relation.
982 *
983 * remote_conds is the list of conditions to be deparsed into the WHERE clause
984 * (or, in the case of upper relations, into the HAVING clause).
985 *
986 * If params_list is not NULL, it receives a list of Params and other-relation
987 * Vars used in the clauses; these values must be transmitted to the remote
988 * server as parameter values.
989 *
990 * If params_list is NULL, we're generating the query for EXPLAIN purposes,
991 * so Params and other-relation Vars should be replaced by dummy values.
992 *
993 * pathkeys is the list of pathkeys to order the result by.
994 *
995 * is_subquery is the flag to indicate whether to deparse the specified
996 * relation as a subquery.
997 *
998 * List of columns selected is returned in retrieved_attrs.
999 */
1000 void
deparseSelectStmtForRel(StringInfo buf,PlannerInfo * root,RelOptInfo * rel,List * tlist,List * remote_conds,List * pathkeys,bool has_final_sort,bool has_limit,bool is_subquery,List ** retrieved_attrs,List ** params_list)1001 deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *rel,
1002 List *tlist, List *remote_conds, List *pathkeys,
1003 bool has_final_sort, bool has_limit, bool is_subquery,
1004 List **retrieved_attrs, List **params_list)
1005 {
1006 deparse_expr_cxt context;
1007 PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
1008 List *quals;
1009
1010 /*
1011 * We handle relations for foreign tables, joins between those and upper
1012 * relations.
1013 */
1014 Assert(IS_JOIN_REL(rel) || IS_SIMPLE_REL(rel) || IS_UPPER_REL(rel));
1015
1016 /* Fill portions of context common to upper, join and base relation */
1017 context.buf = buf;
1018 context.root = root;
1019 context.foreignrel = rel;
1020 context.scanrel = IS_UPPER_REL(rel) ? fpinfo->outerrel : rel;
1021 context.params_list = params_list;
1022
1023 /* Construct SELECT clause */
1024 deparseSelectSql(tlist, is_subquery, retrieved_attrs, &context);
1025
1026 /*
1027 * For upper relations, the WHERE clause is built from the remote
1028 * conditions of the underlying scan relation; otherwise, we can use the
1029 * supplied list of remote conditions directly.
1030 */
1031 if (IS_UPPER_REL(rel))
1032 {
1033 PgFdwRelationInfo *ofpinfo;
1034
1035 ofpinfo = (PgFdwRelationInfo *) fpinfo->outerrel->fdw_private;
1036 quals = ofpinfo->remote_conds;
1037 }
1038 else
1039 quals = remote_conds;
1040
1041 /* Construct FROM and WHERE clauses */
1042 deparseFromExpr(quals, &context);
1043
1044 if (IS_UPPER_REL(rel))
1045 {
1046 /* Append GROUP BY clause */
1047 appendGroupByClause(tlist, &context);
1048
1049 /* Append HAVING clause */
1050 if (remote_conds)
1051 {
1052 appendStringInfoString(buf, " HAVING ");
1053 appendConditions(remote_conds, &context);
1054 }
1055 }
1056
1057 /* Add ORDER BY clause if we found any useful pathkeys */
1058 if (pathkeys)
1059 appendOrderByClause(pathkeys, has_final_sort, &context);
1060
1061 /* Add LIMIT clause if necessary */
1062 if (has_limit)
1063 appendLimitClause(&context);
1064
1065 /* Add any necessary FOR UPDATE/SHARE. */
1066 deparseLockingClause(&context);
1067 }
1068
1069 /*
1070 * Construct a simple SELECT statement that retrieves desired columns
1071 * of the specified foreign table, and append it to "buf". The output
1072 * contains just "SELECT ... ".
1073 *
1074 * We also create an integer List of the columns being retrieved, which is
1075 * returned to *retrieved_attrs, unless we deparse the specified relation
1076 * as a subquery.
1077 *
1078 * tlist is the list of desired columns. is_subquery is the flag to
1079 * indicate whether to deparse the specified relation as a subquery.
1080 * Read prologue of deparseSelectStmtForRel() for details.
1081 */
1082 static void
deparseSelectSql(List * tlist,bool is_subquery,List ** retrieved_attrs,deparse_expr_cxt * context)1083 deparseSelectSql(List *tlist, bool is_subquery, List **retrieved_attrs,
1084 deparse_expr_cxt *context)
1085 {
1086 StringInfo buf = context->buf;
1087 RelOptInfo *foreignrel = context->foreignrel;
1088 PlannerInfo *root = context->root;
1089 PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
1090
1091 /*
1092 * Construct SELECT list
1093 */
1094 appendStringInfoString(buf, "SELECT ");
1095
1096 if (is_subquery)
1097 {
1098 /*
1099 * For a relation that is deparsed as a subquery, emit expressions
1100 * specified in the relation's reltarget. Note that since this is for
1101 * the subquery, no need to care about *retrieved_attrs.
1102 */
1103 deparseSubqueryTargetList(context);
1104 }
1105 else if (IS_JOIN_REL(foreignrel) || IS_UPPER_REL(foreignrel))
1106 {
1107 /*
1108 * For a join or upper relation the input tlist gives the list of
1109 * columns required to be fetched from the foreign server.
1110 */
1111 deparseExplicitTargetList(tlist, false, retrieved_attrs, context);
1112 }
1113 else
1114 {
1115 /*
1116 * For a base relation fpinfo->attrs_used gives the list of columns
1117 * required to be fetched from the foreign server.
1118 */
1119 RangeTblEntry *rte = planner_rt_fetch(foreignrel->relid, root);
1120
1121 /*
1122 * Core code already has some lock on each rel being planned, so we
1123 * can use NoLock here.
1124 */
1125 Relation rel = table_open(rte->relid, NoLock);
1126
1127 deparseTargetList(buf, rte, foreignrel->relid, rel, false,
1128 fpinfo->attrs_used, false, retrieved_attrs);
1129 table_close(rel, NoLock);
1130 }
1131 }
1132
1133 /*
1134 * Construct a FROM clause and, if needed, a WHERE clause, and append those to
1135 * "buf".
1136 *
1137 * quals is the list of clauses to be included in the WHERE clause.
1138 * (These may or may not include RestrictInfo decoration.)
1139 */
1140 static void
deparseFromExpr(List * quals,deparse_expr_cxt * context)1141 deparseFromExpr(List *quals, deparse_expr_cxt *context)
1142 {
1143 StringInfo buf = context->buf;
1144 RelOptInfo *scanrel = context->scanrel;
1145
1146 /* For upper relations, scanrel must be either a joinrel or a baserel */
1147 Assert(!IS_UPPER_REL(context->foreignrel) ||
1148 IS_JOIN_REL(scanrel) || IS_SIMPLE_REL(scanrel));
1149
1150 /* Construct FROM clause */
1151 appendStringInfoString(buf, " FROM ");
1152 deparseFromExprForRel(buf, context->root, scanrel,
1153 (bms_membership(scanrel->relids) == BMS_MULTIPLE),
1154 (Index) 0, NULL, context->params_list);
1155
1156 /* Construct WHERE clause */
1157 if (quals != NIL)
1158 {
1159 appendStringInfoString(buf, " WHERE ");
1160 appendConditions(quals, context);
1161 }
1162 }
1163
1164 /*
1165 * Emit a target list that retrieves the columns specified in attrs_used.
1166 * This is used for both SELECT and RETURNING targetlists; the is_returning
1167 * parameter is true only for a RETURNING targetlist.
1168 *
1169 * The tlist text is appended to buf, and we also create an integer List
1170 * of the columns being retrieved, which is returned to *retrieved_attrs.
1171 *
1172 * If qualify_col is true, add relation alias before the column name.
1173 */
1174 static void
deparseTargetList(StringInfo buf,RangeTblEntry * rte,Index rtindex,Relation rel,bool is_returning,Bitmapset * attrs_used,bool qualify_col,List ** retrieved_attrs)1175 deparseTargetList(StringInfo buf,
1176 RangeTblEntry *rte,
1177 Index rtindex,
1178 Relation rel,
1179 bool is_returning,
1180 Bitmapset *attrs_used,
1181 bool qualify_col,
1182 List **retrieved_attrs)
1183 {
1184 TupleDesc tupdesc = RelationGetDescr(rel);
1185 bool have_wholerow;
1186 bool first;
1187 int i;
1188
1189 *retrieved_attrs = NIL;
1190
1191 /* If there's a whole-row reference, we'll need all the columns. */
1192 have_wholerow = bms_is_member(0 - FirstLowInvalidHeapAttributeNumber,
1193 attrs_used);
1194
1195 first = true;
1196 for (i = 1; i <= tupdesc->natts; i++)
1197 {
1198 Form_pg_attribute attr = TupleDescAttr(tupdesc, i - 1);
1199
1200 /* Ignore dropped attributes. */
1201 if (attr->attisdropped)
1202 continue;
1203
1204 if (have_wholerow ||
1205 bms_is_member(i - FirstLowInvalidHeapAttributeNumber,
1206 attrs_used))
1207 {
1208 if (!first)
1209 appendStringInfoString(buf, ", ");
1210 else if (is_returning)
1211 appendStringInfoString(buf, " RETURNING ");
1212 first = false;
1213
1214 deparseColumnRef(buf, rtindex, i, rte, qualify_col);
1215
1216 *retrieved_attrs = lappend_int(*retrieved_attrs, i);
1217 }
1218 }
1219
1220 /*
1221 * Add ctid if needed. We currently don't support retrieving any other
1222 * system columns.
1223 */
1224 if (bms_is_member(SelfItemPointerAttributeNumber - FirstLowInvalidHeapAttributeNumber,
1225 attrs_used))
1226 {
1227 if (!first)
1228 appendStringInfoString(buf, ", ");
1229 else if (is_returning)
1230 appendStringInfoString(buf, " RETURNING ");
1231 first = false;
1232
1233 if (qualify_col)
1234 ADD_REL_QUALIFIER(buf, rtindex);
1235 appendStringInfoString(buf, "ctid");
1236
1237 *retrieved_attrs = lappend_int(*retrieved_attrs,
1238 SelfItemPointerAttributeNumber);
1239 }
1240
1241 /* Don't generate bad syntax if no undropped columns */
1242 if (first && !is_returning)
1243 appendStringInfoString(buf, "NULL");
1244 }
1245
1246 /*
1247 * Deparse the appropriate locking clause (FOR UPDATE or FOR SHARE) for a
1248 * given relation (context->scanrel).
1249 */
1250 static void
deparseLockingClause(deparse_expr_cxt * context)1251 deparseLockingClause(deparse_expr_cxt *context)
1252 {
1253 StringInfo buf = context->buf;
1254 PlannerInfo *root = context->root;
1255 RelOptInfo *rel = context->scanrel;
1256 PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
1257 int relid = -1;
1258
1259 while ((relid = bms_next_member(rel->relids, relid)) >= 0)
1260 {
1261 /*
1262 * Ignore relation if it appears in a lower subquery. Locking clause
1263 * for such a relation is included in the subquery if necessary.
1264 */
1265 if (bms_is_member(relid, fpinfo->lower_subquery_rels))
1266 continue;
1267
1268 /*
1269 * Add FOR UPDATE/SHARE if appropriate. We apply locking during the
1270 * initial row fetch, rather than later on as is done for local
1271 * tables. The extra roundtrips involved in trying to duplicate the
1272 * local semantics exactly don't seem worthwhile (see also comments
1273 * for RowMarkType).
1274 *
1275 * Note: because we actually run the query as a cursor, this assumes
1276 * that DECLARE CURSOR ... FOR UPDATE is supported, which it isn't
1277 * before 8.3.
1278 */
1279 if (bms_is_member(relid, root->all_result_relids) &&
1280 (root->parse->commandType == CMD_UPDATE ||
1281 root->parse->commandType == CMD_DELETE))
1282 {
1283 /* Relation is UPDATE/DELETE target, so use FOR UPDATE */
1284 appendStringInfoString(buf, " FOR UPDATE");
1285
1286 /* Add the relation alias if we are here for a join relation */
1287 if (IS_JOIN_REL(rel))
1288 appendStringInfo(buf, " OF %s%d", REL_ALIAS_PREFIX, relid);
1289 }
1290 else
1291 {
1292 PlanRowMark *rc = get_plan_rowmark(root->rowMarks, relid);
1293
1294 if (rc)
1295 {
1296 /*
1297 * Relation is specified as a FOR UPDATE/SHARE target, so
1298 * handle that. (But we could also see LCS_NONE, meaning this
1299 * isn't a target relation after all.)
1300 *
1301 * For now, just ignore any [NO] KEY specification, since (a)
1302 * it's not clear what that means for a remote table that we
1303 * don't have complete information about, and (b) it wouldn't
1304 * work anyway on older remote servers. Likewise, we don't
1305 * worry about NOWAIT.
1306 */
1307 switch (rc->strength)
1308 {
1309 case LCS_NONE:
1310 /* No locking needed */
1311 break;
1312 case LCS_FORKEYSHARE:
1313 case LCS_FORSHARE:
1314 appendStringInfoString(buf, " FOR SHARE");
1315 break;
1316 case LCS_FORNOKEYUPDATE:
1317 case LCS_FORUPDATE:
1318 appendStringInfoString(buf, " FOR UPDATE");
1319 break;
1320 }
1321
1322 /* Add the relation alias if we are here for a join relation */
1323 if (bms_membership(rel->relids) == BMS_MULTIPLE &&
1324 rc->strength != LCS_NONE)
1325 appendStringInfo(buf, " OF %s%d", REL_ALIAS_PREFIX, relid);
1326 }
1327 }
1328 }
1329 }
1330
1331 /*
1332 * Deparse conditions from the provided list and append them to buf.
1333 *
1334 * The conditions in the list are assumed to be ANDed. This function is used to
1335 * deparse WHERE clauses, JOIN .. ON clauses and HAVING clauses.
1336 *
1337 * Depending on the caller, the list elements might be either RestrictInfos
1338 * or bare clauses.
1339 */
1340 static void
appendConditions(List * exprs,deparse_expr_cxt * context)1341 appendConditions(List *exprs, deparse_expr_cxt *context)
1342 {
1343 int nestlevel;
1344 ListCell *lc;
1345 bool is_first = true;
1346 StringInfo buf = context->buf;
1347
1348 /* Make sure any constants in the exprs are printed portably */
1349 nestlevel = set_transmission_modes();
1350
1351 foreach(lc, exprs)
1352 {
1353 Expr *expr = (Expr *) lfirst(lc);
1354
1355 /* Extract clause from RestrictInfo, if required */
1356 if (IsA(expr, RestrictInfo))
1357 expr = ((RestrictInfo *) expr)->clause;
1358
1359 /* Connect expressions with "AND" and parenthesize each condition. */
1360 if (!is_first)
1361 appendStringInfoString(buf, " AND ");
1362
1363 appendStringInfoChar(buf, '(');
1364 deparseExpr(expr, context);
1365 appendStringInfoChar(buf, ')');
1366
1367 is_first = false;
1368 }
1369
1370 reset_transmission_modes(nestlevel);
1371 }
1372
1373 /* Output join name for given join type */
1374 const char *
get_jointype_name(JoinType jointype)1375 get_jointype_name(JoinType jointype)
1376 {
1377 switch (jointype)
1378 {
1379 case JOIN_INNER:
1380 return "INNER";
1381
1382 case JOIN_LEFT:
1383 return "LEFT";
1384
1385 case JOIN_RIGHT:
1386 return "RIGHT";
1387
1388 case JOIN_FULL:
1389 return "FULL";
1390
1391 default:
1392 /* Shouldn't come here, but protect from buggy code. */
1393 elog(ERROR, "unsupported join type %d", jointype);
1394 }
1395
1396 /* Keep compiler happy */
1397 return NULL;
1398 }
1399
1400 /*
1401 * Deparse given targetlist and append it to context->buf.
1402 *
1403 * tlist is list of TargetEntry's which in turn contain Var nodes.
1404 *
1405 * retrieved_attrs is the list of continuously increasing integers starting
1406 * from 1. It has same number of entries as tlist.
1407 *
1408 * This is used for both SELECT and RETURNING targetlists; the is_returning
1409 * parameter is true only for a RETURNING targetlist.
1410 */
1411 static void
deparseExplicitTargetList(List * tlist,bool is_returning,List ** retrieved_attrs,deparse_expr_cxt * context)1412 deparseExplicitTargetList(List *tlist,
1413 bool is_returning,
1414 List **retrieved_attrs,
1415 deparse_expr_cxt *context)
1416 {
1417 ListCell *lc;
1418 StringInfo buf = context->buf;
1419 int i = 0;
1420
1421 *retrieved_attrs = NIL;
1422
1423 foreach(lc, tlist)
1424 {
1425 TargetEntry *tle = lfirst_node(TargetEntry, lc);
1426
1427 if (i > 0)
1428 appendStringInfoString(buf, ", ");
1429 else if (is_returning)
1430 appendStringInfoString(buf, " RETURNING ");
1431
1432 deparseExpr((Expr *) tle->expr, context);
1433
1434 *retrieved_attrs = lappend_int(*retrieved_attrs, i + 1);
1435 i++;
1436 }
1437
1438 if (i == 0 && !is_returning)
1439 appendStringInfoString(buf, "NULL");
1440 }
1441
1442 /*
1443 * Emit expressions specified in the given relation's reltarget.
1444 *
1445 * This is used for deparsing the given relation as a subquery.
1446 */
1447 static void
deparseSubqueryTargetList(deparse_expr_cxt * context)1448 deparseSubqueryTargetList(deparse_expr_cxt *context)
1449 {
1450 StringInfo buf = context->buf;
1451 RelOptInfo *foreignrel = context->foreignrel;
1452 bool first;
1453 ListCell *lc;
1454
1455 /* Should only be called in these cases. */
1456 Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel));
1457
1458 first = true;
1459 foreach(lc, foreignrel->reltarget->exprs)
1460 {
1461 Node *node = (Node *) lfirst(lc);
1462
1463 if (!first)
1464 appendStringInfoString(buf, ", ");
1465 first = false;
1466
1467 deparseExpr((Expr *) node, context);
1468 }
1469
1470 /* Don't generate bad syntax if no expressions */
1471 if (first)
1472 appendStringInfoString(buf, "NULL");
1473 }
1474
1475 /*
1476 * Construct FROM clause for given relation
1477 *
1478 * The function constructs ... JOIN ... ON ... for join relation. For a base
1479 * relation it just returns schema-qualified tablename, with the appropriate
1480 * alias if so requested.
1481 *
1482 * 'ignore_rel' is either zero or the RT index of a target relation. In the
1483 * latter case the function constructs FROM clause of UPDATE or USING clause
1484 * of DELETE; it deparses the join relation as if the relation never contained
1485 * the target relation, and creates a List of conditions to be deparsed into
1486 * the top-level WHERE clause, which is returned to *ignore_conds.
1487 */
1488 static void
deparseFromExprForRel(StringInfo buf,PlannerInfo * root,RelOptInfo * foreignrel,bool use_alias,Index ignore_rel,List ** ignore_conds,List ** params_list)1489 deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
1490 bool use_alias, Index ignore_rel, List **ignore_conds,
1491 List **params_list)
1492 {
1493 PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
1494
1495 if (IS_JOIN_REL(foreignrel))
1496 {
1497 StringInfoData join_sql_o;
1498 StringInfoData join_sql_i;
1499 RelOptInfo *outerrel = fpinfo->outerrel;
1500 RelOptInfo *innerrel = fpinfo->innerrel;
1501 bool outerrel_is_target = false;
1502 bool innerrel_is_target = false;
1503
1504 if (ignore_rel > 0 && bms_is_member(ignore_rel, foreignrel->relids))
1505 {
1506 /*
1507 * If this is an inner join, add joinclauses to *ignore_conds and
1508 * set it to empty so that those can be deparsed into the WHERE
1509 * clause. Note that since the target relation can never be
1510 * within the nullable side of an outer join, those could safely
1511 * be pulled up into the WHERE clause (see foreign_join_ok()).
1512 * Note also that since the target relation is only inner-joined
1513 * to any other relation in the query, all conditions in the join
1514 * tree mentioning the target relation could be deparsed into the
1515 * WHERE clause by doing this recursively.
1516 */
1517 if (fpinfo->jointype == JOIN_INNER)
1518 {
1519 *ignore_conds = list_concat(*ignore_conds,
1520 fpinfo->joinclauses);
1521 fpinfo->joinclauses = NIL;
1522 }
1523
1524 /*
1525 * Check if either of the input relations is the target relation.
1526 */
1527 if (outerrel->relid == ignore_rel)
1528 outerrel_is_target = true;
1529 else if (innerrel->relid == ignore_rel)
1530 innerrel_is_target = true;
1531 }
1532
1533 /* Deparse outer relation if not the target relation. */
1534 if (!outerrel_is_target)
1535 {
1536 initStringInfo(&join_sql_o);
1537 deparseRangeTblRef(&join_sql_o, root, outerrel,
1538 fpinfo->make_outerrel_subquery,
1539 ignore_rel, ignore_conds, params_list);
1540
1541 /*
1542 * If inner relation is the target relation, skip deparsing it.
1543 * Note that since the join of the target relation with any other
1544 * relation in the query is an inner join and can never be within
1545 * the nullable side of an outer join, the join could be
1546 * interchanged with higher-level joins (cf. identity 1 on outer
1547 * join reordering shown in src/backend/optimizer/README), which
1548 * means it's safe to skip the target-relation deparsing here.
1549 */
1550 if (innerrel_is_target)
1551 {
1552 Assert(fpinfo->jointype == JOIN_INNER);
1553 Assert(fpinfo->joinclauses == NIL);
1554 appendBinaryStringInfo(buf, join_sql_o.data, join_sql_o.len);
1555 return;
1556 }
1557 }
1558
1559 /* Deparse inner relation if not the target relation. */
1560 if (!innerrel_is_target)
1561 {
1562 initStringInfo(&join_sql_i);
1563 deparseRangeTblRef(&join_sql_i, root, innerrel,
1564 fpinfo->make_innerrel_subquery,
1565 ignore_rel, ignore_conds, params_list);
1566
1567 /*
1568 * If outer relation is the target relation, skip deparsing it.
1569 * See the above note about safety.
1570 */
1571 if (outerrel_is_target)
1572 {
1573 Assert(fpinfo->jointype == JOIN_INNER);
1574 Assert(fpinfo->joinclauses == NIL);
1575 appendBinaryStringInfo(buf, join_sql_i.data, join_sql_i.len);
1576 return;
1577 }
1578 }
1579
1580 /* Neither of the relations is the target relation. */
1581 Assert(!outerrel_is_target && !innerrel_is_target);
1582
1583 /*
1584 * For a join relation FROM clause entry is deparsed as
1585 *
1586 * ((outer relation) <join type> (inner relation) ON (joinclauses))
1587 */
1588 appendStringInfo(buf, "(%s %s JOIN %s ON ", join_sql_o.data,
1589 get_jointype_name(fpinfo->jointype), join_sql_i.data);
1590
1591 /* Append join clause; (TRUE) if no join clause */
1592 if (fpinfo->joinclauses)
1593 {
1594 deparse_expr_cxt context;
1595
1596 context.buf = buf;
1597 context.foreignrel = foreignrel;
1598 context.scanrel = foreignrel;
1599 context.root = root;
1600 context.params_list = params_list;
1601
1602 appendStringInfoChar(buf, '(');
1603 appendConditions(fpinfo->joinclauses, &context);
1604 appendStringInfoChar(buf, ')');
1605 }
1606 else
1607 appendStringInfoString(buf, "(TRUE)");
1608
1609 /* End the FROM clause entry. */
1610 appendStringInfoChar(buf, ')');
1611 }
1612 else
1613 {
1614 RangeTblEntry *rte = planner_rt_fetch(foreignrel->relid, root);
1615
1616 /*
1617 * Core code already has some lock on each rel being planned, so we
1618 * can use NoLock here.
1619 */
1620 Relation rel = table_open(rte->relid, NoLock);
1621
1622 deparseRelation(buf, rel);
1623
1624 /*
1625 * Add a unique alias to avoid any conflict in relation names due to
1626 * pulled up subqueries in the query being built for a pushed down
1627 * join.
1628 */
1629 if (use_alias)
1630 appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, foreignrel->relid);
1631
1632 table_close(rel, NoLock);
1633 }
1634 }
1635
1636 /*
1637 * Append FROM clause entry for the given relation into buf.
1638 */
1639 static void
deparseRangeTblRef(StringInfo buf,PlannerInfo * root,RelOptInfo * foreignrel,bool make_subquery,Index ignore_rel,List ** ignore_conds,List ** params_list)1640 deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
1641 bool make_subquery, Index ignore_rel, List **ignore_conds,
1642 List **params_list)
1643 {
1644 PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
1645
1646 /* Should only be called in these cases. */
1647 Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel));
1648
1649 Assert(fpinfo->local_conds == NIL);
1650
1651 /* If make_subquery is true, deparse the relation as a subquery. */
1652 if (make_subquery)
1653 {
1654 List *retrieved_attrs;
1655 int ncols;
1656
1657 /*
1658 * The given relation shouldn't contain the target relation, because
1659 * this should only happen for input relations for a full join, and
1660 * such relations can never contain an UPDATE/DELETE target.
1661 */
1662 Assert(ignore_rel == 0 ||
1663 !bms_is_member(ignore_rel, foreignrel->relids));
1664
1665 /* Deparse the subquery representing the relation. */
1666 appendStringInfoChar(buf, '(');
1667 deparseSelectStmtForRel(buf, root, foreignrel, NIL,
1668 fpinfo->remote_conds, NIL,
1669 false, false, true,
1670 &retrieved_attrs, params_list);
1671 appendStringInfoChar(buf, ')');
1672
1673 /* Append the relation alias. */
1674 appendStringInfo(buf, " %s%d", SUBQUERY_REL_ALIAS_PREFIX,
1675 fpinfo->relation_index);
1676
1677 /*
1678 * Append the column aliases if needed. Note that the subquery emits
1679 * expressions specified in the relation's reltarget (see
1680 * deparseSubqueryTargetList).
1681 */
1682 ncols = list_length(foreignrel->reltarget->exprs);
1683 if (ncols > 0)
1684 {
1685 int i;
1686
1687 appendStringInfoChar(buf, '(');
1688 for (i = 1; i <= ncols; i++)
1689 {
1690 if (i > 1)
1691 appendStringInfoString(buf, ", ");
1692
1693 appendStringInfo(buf, "%s%d", SUBQUERY_COL_ALIAS_PREFIX, i);
1694 }
1695 appendStringInfoChar(buf, ')');
1696 }
1697 }
1698 else
1699 deparseFromExprForRel(buf, root, foreignrel, true, ignore_rel,
1700 ignore_conds, params_list);
1701 }
1702
1703 /*
1704 * deparse remote INSERT statement
1705 *
1706 * The statement text is appended to buf, and we also create an integer List
1707 * of the columns being retrieved by WITH CHECK OPTION or RETURNING (if any),
1708 * which is returned to *retrieved_attrs.
1709 *
1710 * This also stores end position of the VALUES clause, so that we can rebuild
1711 * an INSERT for a batch of rows later.
1712 */
1713 void
deparseInsertSql(StringInfo buf,RangeTblEntry * rte,Index rtindex,Relation rel,List * targetAttrs,bool doNothing,List * withCheckOptionList,List * returningList,List ** retrieved_attrs,int * values_end_len)1714 deparseInsertSql(StringInfo buf, RangeTblEntry *rte,
1715 Index rtindex, Relation rel,
1716 List *targetAttrs, bool doNothing,
1717 List *withCheckOptionList, List *returningList,
1718 List **retrieved_attrs, int *values_end_len)
1719 {
1720 TupleDesc tupdesc = RelationGetDescr(rel);
1721 AttrNumber pindex;
1722 bool first;
1723 ListCell *lc;
1724
1725 appendStringInfoString(buf, "INSERT INTO ");
1726 deparseRelation(buf, rel);
1727
1728 if (targetAttrs)
1729 {
1730 appendStringInfoChar(buf, '(');
1731
1732 first = true;
1733 foreach(lc, targetAttrs)
1734 {
1735 int attnum = lfirst_int(lc);
1736
1737 if (!first)
1738 appendStringInfoString(buf, ", ");
1739 first = false;
1740
1741 deparseColumnRef(buf, rtindex, attnum, rte, false);
1742 }
1743
1744 appendStringInfoString(buf, ") VALUES (");
1745
1746 pindex = 1;
1747 first = true;
1748 foreach(lc, targetAttrs)
1749 {
1750 int attnum = lfirst_int(lc);
1751 Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
1752
1753 if (!first)
1754 appendStringInfoString(buf, ", ");
1755 first = false;
1756
1757 if (attr->attgenerated)
1758 appendStringInfoString(buf, "DEFAULT");
1759 else
1760 {
1761 appendStringInfo(buf, "$%d", pindex);
1762 pindex++;
1763 }
1764 }
1765
1766 appendStringInfoChar(buf, ')');
1767 }
1768 else
1769 appendStringInfoString(buf, " DEFAULT VALUES");
1770 *values_end_len = buf->len;
1771
1772 if (doNothing)
1773 appendStringInfoString(buf, " ON CONFLICT DO NOTHING");
1774
1775 deparseReturningList(buf, rte, rtindex, rel,
1776 rel->trigdesc && rel->trigdesc->trig_insert_after_row,
1777 withCheckOptionList, returningList, retrieved_attrs);
1778 }
1779
1780 /*
1781 * rebuild remote INSERT statement
1782 *
1783 * Provided a number of rows in a batch, builds INSERT statement with the
1784 * right number of parameters.
1785 */
1786 void
rebuildInsertSql(StringInfo buf,Relation rel,char * orig_query,List * target_attrs,int values_end_len,int num_params,int num_rows)1787 rebuildInsertSql(StringInfo buf, Relation rel,
1788 char *orig_query, List *target_attrs,
1789 int values_end_len, int num_params,
1790 int num_rows)
1791 {
1792 TupleDesc tupdesc = RelationGetDescr(rel);
1793 int i;
1794 int pindex;
1795 bool first;
1796 ListCell *lc;
1797
1798 /* Make sure the values_end_len is sensible */
1799 Assert((values_end_len > 0) && (values_end_len <= strlen(orig_query)));
1800
1801 /* Copy up to the end of the first record from the original query */
1802 appendBinaryStringInfo(buf, orig_query, values_end_len);
1803
1804 /*
1805 * Add records to VALUES clause (we already have parameters for the first
1806 * row, so start at the right offset).
1807 */
1808 pindex = num_params + 1;
1809 for (i = 0; i < num_rows; i++)
1810 {
1811 appendStringInfoString(buf, ", (");
1812
1813 first = true;
1814 foreach(lc, target_attrs)
1815 {
1816 int attnum = lfirst_int(lc);
1817 Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
1818
1819 if (!first)
1820 appendStringInfoString(buf, ", ");
1821 first = false;
1822
1823 if (attr->attgenerated)
1824 appendStringInfoString(buf, "DEFAULT");
1825 else
1826 {
1827 appendStringInfo(buf, "$%d", pindex);
1828 pindex++;
1829 }
1830 }
1831
1832 appendStringInfoChar(buf, ')');
1833 }
1834
1835 /* Copy stuff after VALUES clause from the original query */
1836 appendStringInfoString(buf, orig_query + values_end_len);
1837 }
1838
1839 /*
1840 * deparse remote UPDATE statement
1841 *
1842 * The statement text is appended to buf, and we also create an integer List
1843 * of the columns being retrieved by WITH CHECK OPTION or RETURNING (if any),
1844 * which is returned to *retrieved_attrs.
1845 */
1846 void
deparseUpdateSql(StringInfo buf,RangeTblEntry * rte,Index rtindex,Relation rel,List * targetAttrs,List * withCheckOptionList,List * returningList,List ** retrieved_attrs)1847 deparseUpdateSql(StringInfo buf, RangeTblEntry *rte,
1848 Index rtindex, Relation rel,
1849 List *targetAttrs,
1850 List *withCheckOptionList, List *returningList,
1851 List **retrieved_attrs)
1852 {
1853 TupleDesc tupdesc = RelationGetDescr(rel);
1854 AttrNumber pindex;
1855 bool first;
1856 ListCell *lc;
1857
1858 appendStringInfoString(buf, "UPDATE ");
1859 deparseRelation(buf, rel);
1860 appendStringInfoString(buf, " SET ");
1861
1862 pindex = 2; /* ctid is always the first param */
1863 first = true;
1864 foreach(lc, targetAttrs)
1865 {
1866 int attnum = lfirst_int(lc);
1867 Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
1868
1869 if (!first)
1870 appendStringInfoString(buf, ", ");
1871 first = false;
1872
1873 deparseColumnRef(buf, rtindex, attnum, rte, false);
1874 if (attr->attgenerated)
1875 appendStringInfoString(buf, " = DEFAULT");
1876 else
1877 {
1878 appendStringInfo(buf, " = $%d", pindex);
1879 pindex++;
1880 }
1881 }
1882 appendStringInfoString(buf, " WHERE ctid = $1");
1883
1884 deparseReturningList(buf, rte, rtindex, rel,
1885 rel->trigdesc && rel->trigdesc->trig_update_after_row,
1886 withCheckOptionList, returningList, retrieved_attrs);
1887 }
1888
1889 /*
1890 * deparse remote UPDATE statement
1891 *
1892 * 'buf' is the output buffer to append the statement to
1893 * 'rtindex' is the RT index of the associated target relation
1894 * 'rel' is the relation descriptor for the target relation
1895 * 'foreignrel' is the RelOptInfo for the target relation or the join relation
1896 * containing all base relations in the query
1897 * 'targetlist' is the tlist of the underlying foreign-scan plan node
1898 * (note that this only contains new-value expressions and junk attrs)
1899 * 'targetAttrs' is the target columns of the UPDATE
1900 * 'remote_conds' is the qual clauses that must be evaluated remotely
1901 * '*params_list' is an output list of exprs that will become remote Params
1902 * 'returningList' is the RETURNING targetlist
1903 * '*retrieved_attrs' is an output list of integers of columns being retrieved
1904 * by RETURNING (if any)
1905 */
1906 void
deparseDirectUpdateSql(StringInfo buf,PlannerInfo * root,Index rtindex,Relation rel,RelOptInfo * foreignrel,List * targetlist,List * targetAttrs,List * remote_conds,List ** params_list,List * returningList,List ** retrieved_attrs)1907 deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
1908 Index rtindex, Relation rel,
1909 RelOptInfo *foreignrel,
1910 List *targetlist,
1911 List *targetAttrs,
1912 List *remote_conds,
1913 List **params_list,
1914 List *returningList,
1915 List **retrieved_attrs)
1916 {
1917 deparse_expr_cxt context;
1918 int nestlevel;
1919 bool first;
1920 RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
1921 ListCell *lc,
1922 *lc2;
1923
1924 /* Set up context struct for recursion */
1925 context.root = root;
1926 context.foreignrel = foreignrel;
1927 context.scanrel = foreignrel;
1928 context.buf = buf;
1929 context.params_list = params_list;
1930
1931 appendStringInfoString(buf, "UPDATE ");
1932 deparseRelation(buf, rel);
1933 if (foreignrel->reloptkind == RELOPT_JOINREL)
1934 appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, rtindex);
1935 appendStringInfoString(buf, " SET ");
1936
1937 /* Make sure any constants in the exprs are printed portably */
1938 nestlevel = set_transmission_modes();
1939
1940 first = true;
1941 forboth(lc, targetlist, lc2, targetAttrs)
1942 {
1943 TargetEntry *tle = lfirst_node(TargetEntry, lc);
1944 int attnum = lfirst_int(lc2);
1945
1946 /* update's new-value expressions shouldn't be resjunk */
1947 Assert(!tle->resjunk);
1948
1949 if (!first)
1950 appendStringInfoString(buf, ", ");
1951 first = false;
1952
1953 deparseColumnRef(buf, rtindex, attnum, rte, false);
1954 appendStringInfoString(buf, " = ");
1955 deparseExpr((Expr *) tle->expr, &context);
1956 }
1957
1958 reset_transmission_modes(nestlevel);
1959
1960 if (foreignrel->reloptkind == RELOPT_JOINREL)
1961 {
1962 List *ignore_conds = NIL;
1963
1964 appendStringInfoString(buf, " FROM ");
1965 deparseFromExprForRel(buf, root, foreignrel, true, rtindex,
1966 &ignore_conds, params_list);
1967 remote_conds = list_concat(remote_conds, ignore_conds);
1968 }
1969
1970 if (remote_conds)
1971 {
1972 appendStringInfoString(buf, " WHERE ");
1973 appendConditions(remote_conds, &context);
1974 }
1975
1976 if (foreignrel->reloptkind == RELOPT_JOINREL)
1977 deparseExplicitTargetList(returningList, true, retrieved_attrs,
1978 &context);
1979 else
1980 deparseReturningList(buf, rte, rtindex, rel, false,
1981 NIL, returningList, retrieved_attrs);
1982 }
1983
1984 /*
1985 * deparse remote DELETE statement
1986 *
1987 * The statement text is appended to buf, and we also create an integer List
1988 * of the columns being retrieved by RETURNING (if any), which is returned
1989 * to *retrieved_attrs.
1990 */
1991 void
deparseDeleteSql(StringInfo buf,RangeTblEntry * rte,Index rtindex,Relation rel,List * returningList,List ** retrieved_attrs)1992 deparseDeleteSql(StringInfo buf, RangeTblEntry *rte,
1993 Index rtindex, Relation rel,
1994 List *returningList,
1995 List **retrieved_attrs)
1996 {
1997 appendStringInfoString(buf, "DELETE FROM ");
1998 deparseRelation(buf, rel);
1999 appendStringInfoString(buf, " WHERE ctid = $1");
2000
2001 deparseReturningList(buf, rte, rtindex, rel,
2002 rel->trigdesc && rel->trigdesc->trig_delete_after_row,
2003 NIL, returningList, retrieved_attrs);
2004 }
2005
2006 /*
2007 * deparse remote DELETE statement
2008 *
2009 * 'buf' is the output buffer to append the statement to
2010 * 'rtindex' is the RT index of the associated target relation
2011 * 'rel' is the relation descriptor for the target relation
2012 * 'foreignrel' is the RelOptInfo for the target relation or the join relation
2013 * containing all base relations in the query
2014 * 'remote_conds' is the qual clauses that must be evaluated remotely
2015 * '*params_list' is an output list of exprs that will become remote Params
2016 * 'returningList' is the RETURNING targetlist
2017 * '*retrieved_attrs' is an output list of integers of columns being retrieved
2018 * by RETURNING (if any)
2019 */
2020 void
deparseDirectDeleteSql(StringInfo buf,PlannerInfo * root,Index rtindex,Relation rel,RelOptInfo * foreignrel,List * remote_conds,List ** params_list,List * returningList,List ** retrieved_attrs)2021 deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
2022 Index rtindex, Relation rel,
2023 RelOptInfo *foreignrel,
2024 List *remote_conds,
2025 List **params_list,
2026 List *returningList,
2027 List **retrieved_attrs)
2028 {
2029 deparse_expr_cxt context;
2030
2031 /* Set up context struct for recursion */
2032 context.root = root;
2033 context.foreignrel = foreignrel;
2034 context.scanrel = foreignrel;
2035 context.buf = buf;
2036 context.params_list = params_list;
2037
2038 appendStringInfoString(buf, "DELETE FROM ");
2039 deparseRelation(buf, rel);
2040 if (foreignrel->reloptkind == RELOPT_JOINREL)
2041 appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, rtindex);
2042
2043 if (foreignrel->reloptkind == RELOPT_JOINREL)
2044 {
2045 List *ignore_conds = NIL;
2046
2047 appendStringInfoString(buf, " USING ");
2048 deparseFromExprForRel(buf, root, foreignrel, true, rtindex,
2049 &ignore_conds, params_list);
2050 remote_conds = list_concat(remote_conds, ignore_conds);
2051 }
2052
2053 if (remote_conds)
2054 {
2055 appendStringInfoString(buf, " WHERE ");
2056 appendConditions(remote_conds, &context);
2057 }
2058
2059 if (foreignrel->reloptkind == RELOPT_JOINREL)
2060 deparseExplicitTargetList(returningList, true, retrieved_attrs,
2061 &context);
2062 else
2063 deparseReturningList(buf, planner_rt_fetch(rtindex, root),
2064 rtindex, rel, false,
2065 NIL, returningList, retrieved_attrs);
2066 }
2067
2068 /*
2069 * Add a RETURNING clause, if needed, to an INSERT/UPDATE/DELETE.
2070 */
2071 static void
deparseReturningList(StringInfo buf,RangeTblEntry * rte,Index rtindex,Relation rel,bool trig_after_row,List * withCheckOptionList,List * returningList,List ** retrieved_attrs)2072 deparseReturningList(StringInfo buf, RangeTblEntry *rte,
2073 Index rtindex, Relation rel,
2074 bool trig_after_row,
2075 List *withCheckOptionList,
2076 List *returningList,
2077 List **retrieved_attrs)
2078 {
2079 Bitmapset *attrs_used = NULL;
2080
2081 if (trig_after_row)
2082 {
2083 /* whole-row reference acquires all non-system columns */
2084 attrs_used =
2085 bms_make_singleton(0 - FirstLowInvalidHeapAttributeNumber);
2086 }
2087
2088 if (withCheckOptionList != NIL)
2089 {
2090 /*
2091 * We need the attrs, non-system and system, mentioned in the local
2092 * query's WITH CHECK OPTION list.
2093 *
2094 * Note: we do this to ensure that WCO constraints will be evaluated
2095 * on the data actually inserted/updated on the remote side, which
2096 * might differ from the data supplied by the core code, for example
2097 * as a result of remote triggers.
2098 */
2099 pull_varattnos((Node *) withCheckOptionList, rtindex,
2100 &attrs_used);
2101 }
2102
2103 if (returningList != NIL)
2104 {
2105 /*
2106 * We need the attrs, non-system and system, mentioned in the local
2107 * query's RETURNING list.
2108 */
2109 pull_varattnos((Node *) returningList, rtindex,
2110 &attrs_used);
2111 }
2112
2113 if (attrs_used != NULL)
2114 deparseTargetList(buf, rte, rtindex, rel, true, attrs_used, false,
2115 retrieved_attrs);
2116 else
2117 *retrieved_attrs = NIL;
2118 }
2119
2120 /*
2121 * Construct SELECT statement to acquire size in blocks of given relation.
2122 *
2123 * Note: we use local definition of block size, not remote definition.
2124 * This is perhaps debatable.
2125 *
2126 * Note: pg_relation_size() exists in 8.1 and later.
2127 */
2128 void
deparseAnalyzeSizeSql(StringInfo buf,Relation rel)2129 deparseAnalyzeSizeSql(StringInfo buf, Relation rel)
2130 {
2131 StringInfoData relname;
2132
2133 /* We'll need the remote relation name as a literal. */
2134 initStringInfo(&relname);
2135 deparseRelation(&relname, rel);
2136
2137 appendStringInfoString(buf, "SELECT pg_catalog.pg_relation_size(");
2138 deparseStringLiteral(buf, relname.data);
2139 appendStringInfo(buf, "::pg_catalog.regclass) / %d", BLCKSZ);
2140 }
2141
2142 /*
2143 * Construct SELECT statement to acquire sample rows of given relation.
2144 *
2145 * SELECT command is appended to buf, and list of columns retrieved
2146 * is returned to *retrieved_attrs.
2147 */
2148 void
deparseAnalyzeSql(StringInfo buf,Relation rel,List ** retrieved_attrs)2149 deparseAnalyzeSql(StringInfo buf, Relation rel, List **retrieved_attrs)
2150 {
2151 Oid relid = RelationGetRelid(rel);
2152 TupleDesc tupdesc = RelationGetDescr(rel);
2153 int i;
2154 char *colname;
2155 List *options;
2156 ListCell *lc;
2157 bool first = true;
2158
2159 *retrieved_attrs = NIL;
2160
2161 appendStringInfoString(buf, "SELECT ");
2162 for (i = 0; i < tupdesc->natts; i++)
2163 {
2164 /* Ignore dropped columns. */
2165 if (TupleDescAttr(tupdesc, i)->attisdropped)
2166 continue;
2167
2168 if (!first)
2169 appendStringInfoString(buf, ", ");
2170 first = false;
2171
2172 /* Use attribute name or column_name option. */
2173 colname = NameStr(TupleDescAttr(tupdesc, i)->attname);
2174 options = GetForeignColumnOptions(relid, i + 1);
2175
2176 foreach(lc, options)
2177 {
2178 DefElem *def = (DefElem *) lfirst(lc);
2179
2180 if (strcmp(def->defname, "column_name") == 0)
2181 {
2182 colname = defGetString(def);
2183 break;
2184 }
2185 }
2186
2187 appendStringInfoString(buf, quote_identifier(colname));
2188
2189 *retrieved_attrs = lappend_int(*retrieved_attrs, i + 1);
2190 }
2191
2192 /* Don't generate bad syntax for zero-column relation. */
2193 if (first)
2194 appendStringInfoString(buf, "NULL");
2195
2196 /*
2197 * Construct FROM clause
2198 */
2199 appendStringInfoString(buf, " FROM ");
2200 deparseRelation(buf, rel);
2201 }
2202
2203 /*
2204 * Construct a simple "TRUNCATE rel" statement
2205 */
2206 void
deparseTruncateSql(StringInfo buf,List * rels,DropBehavior behavior,bool restart_seqs)2207 deparseTruncateSql(StringInfo buf,
2208 List *rels,
2209 DropBehavior behavior,
2210 bool restart_seqs)
2211 {
2212 ListCell *cell;
2213
2214 appendStringInfoString(buf, "TRUNCATE ");
2215
2216 foreach(cell, rels)
2217 {
2218 Relation rel = lfirst(cell);
2219
2220 if (cell != list_head(rels))
2221 appendStringInfoString(buf, ", ");
2222
2223 deparseRelation(buf, rel);
2224 }
2225
2226 appendStringInfo(buf, " %s IDENTITY",
2227 restart_seqs ? "RESTART" : "CONTINUE");
2228
2229 if (behavior == DROP_RESTRICT)
2230 appendStringInfoString(buf, " RESTRICT");
2231 else if (behavior == DROP_CASCADE)
2232 appendStringInfoString(buf, " CASCADE");
2233 }
2234
2235 /*
2236 * Construct name to use for given column, and emit it into buf.
2237 * If it has a column_name FDW option, use that instead of attribute name.
2238 *
2239 * If qualify_col is true, qualify column name with the alias of relation.
2240 */
2241 static void
deparseColumnRef(StringInfo buf,int varno,int varattno,RangeTblEntry * rte,bool qualify_col)2242 deparseColumnRef(StringInfo buf, int varno, int varattno, RangeTblEntry *rte,
2243 bool qualify_col)
2244 {
2245 /* We support fetching the remote side's CTID and OID. */
2246 if (varattno == SelfItemPointerAttributeNumber)
2247 {
2248 if (qualify_col)
2249 ADD_REL_QUALIFIER(buf, varno);
2250 appendStringInfoString(buf, "ctid");
2251 }
2252 else if (varattno < 0)
2253 {
2254 /*
2255 * All other system attributes are fetched as 0, except for table OID,
2256 * which is fetched as the local table OID. However, we must be
2257 * careful; the table could be beneath an outer join, in which case it
2258 * must go to NULL whenever the rest of the row does.
2259 */
2260 Oid fetchval = 0;
2261
2262 if (varattno == TableOidAttributeNumber)
2263 fetchval = rte->relid;
2264
2265 if (qualify_col)
2266 {
2267 appendStringInfoString(buf, "CASE WHEN (");
2268 ADD_REL_QUALIFIER(buf, varno);
2269 appendStringInfo(buf, "*)::text IS NOT NULL THEN %u END", fetchval);
2270 }
2271 else
2272 appendStringInfo(buf, "%u", fetchval);
2273 }
2274 else if (varattno == 0)
2275 {
2276 /* Whole row reference */
2277 Relation rel;
2278 Bitmapset *attrs_used;
2279
2280 /* Required only to be passed down to deparseTargetList(). */
2281 List *retrieved_attrs;
2282
2283 /*
2284 * The lock on the relation will be held by upper callers, so it's
2285 * fine to open it with no lock here.
2286 */
2287 rel = table_open(rte->relid, NoLock);
2288
2289 /*
2290 * The local name of the foreign table can not be recognized by the
2291 * foreign server and the table it references on foreign server might
2292 * have different column ordering or different columns than those
2293 * declared locally. Hence we have to deparse whole-row reference as
2294 * ROW(columns referenced locally). Construct this by deparsing a
2295 * "whole row" attribute.
2296 */
2297 attrs_used = bms_add_member(NULL,
2298 0 - FirstLowInvalidHeapAttributeNumber);
2299
2300 /*
2301 * In case the whole-row reference is under an outer join then it has
2302 * to go NULL whenever the rest of the row goes NULL. Deparsing a join
2303 * query would always involve multiple relations, thus qualify_col
2304 * would be true.
2305 */
2306 if (qualify_col)
2307 {
2308 appendStringInfoString(buf, "CASE WHEN (");
2309 ADD_REL_QUALIFIER(buf, varno);
2310 appendStringInfoString(buf, "*)::text IS NOT NULL THEN ");
2311 }
2312
2313 appendStringInfoString(buf, "ROW(");
2314 deparseTargetList(buf, rte, varno, rel, false, attrs_used, qualify_col,
2315 &retrieved_attrs);
2316 appendStringInfoChar(buf, ')');
2317
2318 /* Complete the CASE WHEN statement started above. */
2319 if (qualify_col)
2320 appendStringInfoString(buf, " END");
2321
2322 table_close(rel, NoLock);
2323 bms_free(attrs_used);
2324 }
2325 else
2326 {
2327 char *colname = NULL;
2328 List *options;
2329 ListCell *lc;
2330
2331 /* varno must not be any of OUTER_VAR, INNER_VAR and INDEX_VAR. */
2332 Assert(!IS_SPECIAL_VARNO(varno));
2333
2334 /*
2335 * If it's a column of a foreign table, and it has the column_name FDW
2336 * option, use that value.
2337 */
2338 options = GetForeignColumnOptions(rte->relid, varattno);
2339 foreach(lc, options)
2340 {
2341 DefElem *def = (DefElem *) lfirst(lc);
2342
2343 if (strcmp(def->defname, "column_name") == 0)
2344 {
2345 colname = defGetString(def);
2346 break;
2347 }
2348 }
2349
2350 /*
2351 * If it's a column of a regular table or it doesn't have column_name
2352 * FDW option, use attribute name.
2353 */
2354 if (colname == NULL)
2355 colname = get_attname(rte->relid, varattno, false);
2356
2357 if (qualify_col)
2358 ADD_REL_QUALIFIER(buf, varno);
2359
2360 appendStringInfoString(buf, quote_identifier(colname));
2361 }
2362 }
2363
2364 /*
2365 * Append remote name of specified foreign table to buf.
2366 * Use value of table_name FDW option (if any) instead of relation's name.
2367 * Similarly, schema_name FDW option overrides schema name.
2368 */
2369 static void
deparseRelation(StringInfo buf,Relation rel)2370 deparseRelation(StringInfo buf, Relation rel)
2371 {
2372 ForeignTable *table;
2373 const char *nspname = NULL;
2374 const char *relname = NULL;
2375 ListCell *lc;
2376
2377 /* obtain additional catalog information. */
2378 table = GetForeignTable(RelationGetRelid(rel));
2379
2380 /*
2381 * Use value of FDW options if any, instead of the name of object itself.
2382 */
2383 foreach(lc, table->options)
2384 {
2385 DefElem *def = (DefElem *) lfirst(lc);
2386
2387 if (strcmp(def->defname, "schema_name") == 0)
2388 nspname = defGetString(def);
2389 else if (strcmp(def->defname, "table_name") == 0)
2390 relname = defGetString(def);
2391 }
2392
2393 /*
2394 * Note: we could skip printing the schema name if it's pg_catalog, but
2395 * that doesn't seem worth the trouble.
2396 */
2397 if (nspname == NULL)
2398 nspname = get_namespace_name(RelationGetNamespace(rel));
2399 if (relname == NULL)
2400 relname = RelationGetRelationName(rel);
2401
2402 appendStringInfo(buf, "%s.%s",
2403 quote_identifier(nspname), quote_identifier(relname));
2404 }
2405
2406 /*
2407 * Append a SQL string literal representing "val" to buf.
2408 */
2409 void
deparseStringLiteral(StringInfo buf,const char * val)2410 deparseStringLiteral(StringInfo buf, const char *val)
2411 {
2412 const char *valptr;
2413
2414 /*
2415 * Rather than making assumptions about the remote server's value of
2416 * standard_conforming_strings, always use E'foo' syntax if there are any
2417 * backslashes. This will fail on remote servers before 8.1, but those
2418 * are long out of support.
2419 */
2420 if (strchr(val, '\\') != NULL)
2421 appendStringInfoChar(buf, ESCAPE_STRING_SYNTAX);
2422 appendStringInfoChar(buf, '\'');
2423 for (valptr = val; *valptr; valptr++)
2424 {
2425 char ch = *valptr;
2426
2427 if (SQL_STR_DOUBLE(ch, true))
2428 appendStringInfoChar(buf, ch);
2429 appendStringInfoChar(buf, ch);
2430 }
2431 appendStringInfoChar(buf, '\'');
2432 }
2433
2434 /*
2435 * Deparse given expression into context->buf.
2436 *
2437 * This function must support all the same node types that foreign_expr_walker
2438 * accepts.
2439 *
2440 * Note: unlike ruleutils.c, we just use a simple hard-wired parenthesization
2441 * scheme: anything more complex than a Var, Const, function call or cast
2442 * should be self-parenthesized.
2443 */
2444 static void
deparseExpr(Expr * node,deparse_expr_cxt * context)2445 deparseExpr(Expr *node, deparse_expr_cxt *context)
2446 {
2447 if (node == NULL)
2448 return;
2449
2450 switch (nodeTag(node))
2451 {
2452 case T_Var:
2453 deparseVar((Var *) node, context);
2454 break;
2455 case T_Const:
2456 deparseConst((Const *) node, context, 0);
2457 break;
2458 case T_Param:
2459 deparseParam((Param *) node, context);
2460 break;
2461 case T_SubscriptingRef:
2462 deparseSubscriptingRef((SubscriptingRef *) node, context);
2463 break;
2464 case T_FuncExpr:
2465 deparseFuncExpr((FuncExpr *) node, context);
2466 break;
2467 case T_OpExpr:
2468 deparseOpExpr((OpExpr *) node, context);
2469 break;
2470 case T_DistinctExpr:
2471 deparseDistinctExpr((DistinctExpr *) node, context);
2472 break;
2473 case T_ScalarArrayOpExpr:
2474 deparseScalarArrayOpExpr((ScalarArrayOpExpr *) node, context);
2475 break;
2476 case T_RelabelType:
2477 deparseRelabelType((RelabelType *) node, context);
2478 break;
2479 case T_BoolExpr:
2480 deparseBoolExpr((BoolExpr *) node, context);
2481 break;
2482 case T_NullTest:
2483 deparseNullTest((NullTest *) node, context);
2484 break;
2485 case T_ArrayExpr:
2486 deparseArrayExpr((ArrayExpr *) node, context);
2487 break;
2488 case T_Aggref:
2489 deparseAggref((Aggref *) node, context);
2490 break;
2491 default:
2492 elog(ERROR, "unsupported expression type for deparse: %d",
2493 (int) nodeTag(node));
2494 break;
2495 }
2496 }
2497
2498 /*
2499 * Deparse given Var node into context->buf.
2500 *
2501 * If the Var belongs to the foreign relation, just print its remote name.
2502 * Otherwise, it's effectively a Param (and will in fact be a Param at
2503 * run time). Handle it the same way we handle plain Params --- see
2504 * deparseParam for comments.
2505 */
2506 static void
deparseVar(Var * node,deparse_expr_cxt * context)2507 deparseVar(Var *node, deparse_expr_cxt *context)
2508 {
2509 Relids relids = context->scanrel->relids;
2510 int relno;
2511 int colno;
2512
2513 /* Qualify columns when multiple relations are involved. */
2514 bool qualify_col = (bms_membership(relids) == BMS_MULTIPLE);
2515
2516 /*
2517 * If the Var belongs to the foreign relation that is deparsed as a
2518 * subquery, use the relation and column alias to the Var provided by the
2519 * subquery, instead of the remote name.
2520 */
2521 if (is_subquery_var(node, context->scanrel, &relno, &colno))
2522 {
2523 appendStringInfo(context->buf, "%s%d.%s%d",
2524 SUBQUERY_REL_ALIAS_PREFIX, relno,
2525 SUBQUERY_COL_ALIAS_PREFIX, colno);
2526 return;
2527 }
2528
2529 if (bms_is_member(node->varno, relids) && node->varlevelsup == 0)
2530 deparseColumnRef(context->buf, node->varno, node->varattno,
2531 planner_rt_fetch(node->varno, context->root),
2532 qualify_col);
2533 else
2534 {
2535 /* Treat like a Param */
2536 if (context->params_list)
2537 {
2538 int pindex = 0;
2539 ListCell *lc;
2540
2541 /* find its index in params_list */
2542 foreach(lc, *context->params_list)
2543 {
2544 pindex++;
2545 if (equal(node, (Node *) lfirst(lc)))
2546 break;
2547 }
2548 if (lc == NULL)
2549 {
2550 /* not in list, so add it */
2551 pindex++;
2552 *context->params_list = lappend(*context->params_list, node);
2553 }
2554
2555 printRemoteParam(pindex, node->vartype, node->vartypmod, context);
2556 }
2557 else
2558 {
2559 printRemotePlaceholder(node->vartype, node->vartypmod, context);
2560 }
2561 }
2562 }
2563
2564 /*
2565 * Deparse given constant value into context->buf.
2566 *
2567 * This function has to be kept in sync with ruleutils.c's get_const_expr.
2568 * As for that function, showtype can be -1 to never show "::typename" decoration,
2569 * or +1 to always show it, or 0 to show it only if the constant wouldn't be assumed
2570 * to be the right type by default.
2571 */
2572 static void
deparseConst(Const * node,deparse_expr_cxt * context,int showtype)2573 deparseConst(Const *node, deparse_expr_cxt *context, int showtype)
2574 {
2575 StringInfo buf = context->buf;
2576 Oid typoutput;
2577 bool typIsVarlena;
2578 char *extval;
2579 bool isfloat = false;
2580 bool needlabel;
2581
2582 if (node->constisnull)
2583 {
2584 appendStringInfoString(buf, "NULL");
2585 if (showtype >= 0)
2586 appendStringInfo(buf, "::%s",
2587 deparse_type_name(node->consttype,
2588 node->consttypmod));
2589 return;
2590 }
2591
2592 getTypeOutputInfo(node->consttype,
2593 &typoutput, &typIsVarlena);
2594 extval = OidOutputFunctionCall(typoutput, node->constvalue);
2595
2596 switch (node->consttype)
2597 {
2598 case INT2OID:
2599 case INT4OID:
2600 case INT8OID:
2601 case OIDOID:
2602 case FLOAT4OID:
2603 case FLOAT8OID:
2604 case NUMERICOID:
2605 {
2606 /*
2607 * No need to quote unless it's a special value such as 'NaN'.
2608 * See comments in get_const_expr().
2609 */
2610 if (strspn(extval, "0123456789+-eE.") == strlen(extval))
2611 {
2612 if (extval[0] == '+' || extval[0] == '-')
2613 appendStringInfo(buf, "(%s)", extval);
2614 else
2615 appendStringInfoString(buf, extval);
2616 if (strcspn(extval, "eE.") != strlen(extval))
2617 isfloat = true; /* it looks like a float */
2618 }
2619 else
2620 appendStringInfo(buf, "'%s'", extval);
2621 }
2622 break;
2623 case BITOID:
2624 case VARBITOID:
2625 appendStringInfo(buf, "B'%s'", extval);
2626 break;
2627 case BOOLOID:
2628 if (strcmp(extval, "t") == 0)
2629 appendStringInfoString(buf, "true");
2630 else
2631 appendStringInfoString(buf, "false");
2632 break;
2633 default:
2634 deparseStringLiteral(buf, extval);
2635 break;
2636 }
2637
2638 pfree(extval);
2639
2640 if (showtype < 0)
2641 return;
2642
2643 /*
2644 * For showtype == 0, append ::typename unless the constant will be
2645 * implicitly typed as the right type when it is read in.
2646 *
2647 * XXX this code has to be kept in sync with the behavior of the parser,
2648 * especially make_const.
2649 */
2650 switch (node->consttype)
2651 {
2652 case BOOLOID:
2653 case INT4OID:
2654 case UNKNOWNOID:
2655 needlabel = false;
2656 break;
2657 case NUMERICOID:
2658 needlabel = !isfloat || (node->consttypmod >= 0);
2659 break;
2660 default:
2661 needlabel = true;
2662 break;
2663 }
2664 if (needlabel || showtype > 0)
2665 appendStringInfo(buf, "::%s",
2666 deparse_type_name(node->consttype,
2667 node->consttypmod));
2668 }
2669
2670 /*
2671 * Deparse given Param node.
2672 *
2673 * If we're generating the query "for real", add the Param to
2674 * context->params_list if it's not already present, and then use its index
2675 * in that list as the remote parameter number. During EXPLAIN, there's
2676 * no need to identify a parameter number.
2677 */
2678 static void
deparseParam(Param * node,deparse_expr_cxt * context)2679 deparseParam(Param *node, deparse_expr_cxt *context)
2680 {
2681 if (context->params_list)
2682 {
2683 int pindex = 0;
2684 ListCell *lc;
2685
2686 /* find its index in params_list */
2687 foreach(lc, *context->params_list)
2688 {
2689 pindex++;
2690 if (equal(node, (Node *) lfirst(lc)))
2691 break;
2692 }
2693 if (lc == NULL)
2694 {
2695 /* not in list, so add it */
2696 pindex++;
2697 *context->params_list = lappend(*context->params_list, node);
2698 }
2699
2700 printRemoteParam(pindex, node->paramtype, node->paramtypmod, context);
2701 }
2702 else
2703 {
2704 printRemotePlaceholder(node->paramtype, node->paramtypmod, context);
2705 }
2706 }
2707
2708 /*
2709 * Deparse a container subscript expression.
2710 */
2711 static void
deparseSubscriptingRef(SubscriptingRef * node,deparse_expr_cxt * context)2712 deparseSubscriptingRef(SubscriptingRef *node, deparse_expr_cxt *context)
2713 {
2714 StringInfo buf = context->buf;
2715 ListCell *lowlist_item;
2716 ListCell *uplist_item;
2717
2718 /* Always parenthesize the expression. */
2719 appendStringInfoChar(buf, '(');
2720
2721 /*
2722 * Deparse referenced array expression first. If that expression includes
2723 * a cast, we have to parenthesize to prevent the array subscript from
2724 * being taken as typename decoration. We can avoid that in the typical
2725 * case of subscripting a Var, but otherwise do it.
2726 */
2727 if (IsA(node->refexpr, Var))
2728 deparseExpr(node->refexpr, context);
2729 else
2730 {
2731 appendStringInfoChar(buf, '(');
2732 deparseExpr(node->refexpr, context);
2733 appendStringInfoChar(buf, ')');
2734 }
2735
2736 /* Deparse subscript expressions. */
2737 lowlist_item = list_head(node->reflowerindexpr); /* could be NULL */
2738 foreach(uplist_item, node->refupperindexpr)
2739 {
2740 appendStringInfoChar(buf, '[');
2741 if (lowlist_item)
2742 {
2743 deparseExpr(lfirst(lowlist_item), context);
2744 appendStringInfoChar(buf, ':');
2745 lowlist_item = lnext(node->reflowerindexpr, lowlist_item);
2746 }
2747 deparseExpr(lfirst(uplist_item), context);
2748 appendStringInfoChar(buf, ']');
2749 }
2750
2751 appendStringInfoChar(buf, ')');
2752 }
2753
2754 /*
2755 * Deparse a function call.
2756 */
2757 static void
deparseFuncExpr(FuncExpr * node,deparse_expr_cxt * context)2758 deparseFuncExpr(FuncExpr *node, deparse_expr_cxt *context)
2759 {
2760 StringInfo buf = context->buf;
2761 bool use_variadic;
2762 bool first;
2763 ListCell *arg;
2764
2765 /*
2766 * If the function call came from an implicit coercion, then just show the
2767 * first argument.
2768 */
2769 if (node->funcformat == COERCE_IMPLICIT_CAST)
2770 {
2771 deparseExpr((Expr *) linitial(node->args), context);
2772 return;
2773 }
2774
2775 /*
2776 * If the function call came from a cast, then show the first argument
2777 * plus an explicit cast operation.
2778 */
2779 if (node->funcformat == COERCE_EXPLICIT_CAST)
2780 {
2781 Oid rettype = node->funcresulttype;
2782 int32 coercedTypmod;
2783
2784 /* Get the typmod if this is a length-coercion function */
2785 (void) exprIsLengthCoercion((Node *) node, &coercedTypmod);
2786
2787 deparseExpr((Expr *) linitial(node->args), context);
2788 appendStringInfo(buf, "::%s",
2789 deparse_type_name(rettype, coercedTypmod));
2790 return;
2791 }
2792
2793 /* Check if need to print VARIADIC (cf. ruleutils.c) */
2794 use_variadic = node->funcvariadic;
2795
2796 /*
2797 * Normal function: display as proname(args).
2798 */
2799 appendFunctionName(node->funcid, context);
2800 appendStringInfoChar(buf, '(');
2801
2802 /* ... and all the arguments */
2803 first = true;
2804 foreach(arg, node->args)
2805 {
2806 if (!first)
2807 appendStringInfoString(buf, ", ");
2808 if (use_variadic && lnext(node->args, arg) == NULL)
2809 appendStringInfoString(buf, "VARIADIC ");
2810 deparseExpr((Expr *) lfirst(arg), context);
2811 first = false;
2812 }
2813 appendStringInfoChar(buf, ')');
2814 }
2815
2816 /*
2817 * Deparse given operator expression. To avoid problems around
2818 * priority of operations, we always parenthesize the arguments.
2819 */
2820 static void
deparseOpExpr(OpExpr * node,deparse_expr_cxt * context)2821 deparseOpExpr(OpExpr *node, deparse_expr_cxt *context)
2822 {
2823 StringInfo buf = context->buf;
2824 HeapTuple tuple;
2825 Form_pg_operator form;
2826 char oprkind;
2827
2828 /* Retrieve information about the operator from system catalog. */
2829 tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(node->opno));
2830 if (!HeapTupleIsValid(tuple))
2831 elog(ERROR, "cache lookup failed for operator %u", node->opno);
2832 form = (Form_pg_operator) GETSTRUCT(tuple);
2833 oprkind = form->oprkind;
2834
2835 /* Sanity check. */
2836 Assert((oprkind == 'l' && list_length(node->args) == 1) ||
2837 (oprkind == 'b' && list_length(node->args) == 2));
2838
2839 /* Always parenthesize the expression. */
2840 appendStringInfoChar(buf, '(');
2841
2842 /* Deparse left operand, if any. */
2843 if (oprkind == 'b')
2844 {
2845 deparseExpr(linitial(node->args), context);
2846 appendStringInfoChar(buf, ' ');
2847 }
2848
2849 /* Deparse operator name. */
2850 deparseOperatorName(buf, form);
2851
2852 /* Deparse right operand. */
2853 appendStringInfoChar(buf, ' ');
2854 deparseExpr(llast(node->args), context);
2855
2856 appendStringInfoChar(buf, ')');
2857
2858 ReleaseSysCache(tuple);
2859 }
2860
2861 /*
2862 * Print the name of an operator.
2863 */
2864 static void
deparseOperatorName(StringInfo buf,Form_pg_operator opform)2865 deparseOperatorName(StringInfo buf, Form_pg_operator opform)
2866 {
2867 char *opname;
2868
2869 /* opname is not a SQL identifier, so we should not quote it. */
2870 opname = NameStr(opform->oprname);
2871
2872 /* Print schema name only if it's not pg_catalog */
2873 if (opform->oprnamespace != PG_CATALOG_NAMESPACE)
2874 {
2875 const char *opnspname;
2876
2877 opnspname = get_namespace_name(opform->oprnamespace);
2878 /* Print fully qualified operator name. */
2879 appendStringInfo(buf, "OPERATOR(%s.%s)",
2880 quote_identifier(opnspname), opname);
2881 }
2882 else
2883 {
2884 /* Just print operator name. */
2885 appendStringInfoString(buf, opname);
2886 }
2887 }
2888
2889 /*
2890 * Deparse IS DISTINCT FROM.
2891 */
2892 static void
deparseDistinctExpr(DistinctExpr * node,deparse_expr_cxt * context)2893 deparseDistinctExpr(DistinctExpr *node, deparse_expr_cxt *context)
2894 {
2895 StringInfo buf = context->buf;
2896
2897 Assert(list_length(node->args) == 2);
2898
2899 appendStringInfoChar(buf, '(');
2900 deparseExpr(linitial(node->args), context);
2901 appendStringInfoString(buf, " IS DISTINCT FROM ");
2902 deparseExpr(lsecond(node->args), context);
2903 appendStringInfoChar(buf, ')');
2904 }
2905
2906 /*
2907 * Deparse given ScalarArrayOpExpr expression. To avoid problems
2908 * around priority of operations, we always parenthesize the arguments.
2909 */
2910 static void
deparseScalarArrayOpExpr(ScalarArrayOpExpr * node,deparse_expr_cxt * context)2911 deparseScalarArrayOpExpr(ScalarArrayOpExpr *node, deparse_expr_cxt *context)
2912 {
2913 StringInfo buf = context->buf;
2914 HeapTuple tuple;
2915 Form_pg_operator form;
2916 Expr *arg1;
2917 Expr *arg2;
2918
2919 /* Retrieve information about the operator from system catalog. */
2920 tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(node->opno));
2921 if (!HeapTupleIsValid(tuple))
2922 elog(ERROR, "cache lookup failed for operator %u", node->opno);
2923 form = (Form_pg_operator) GETSTRUCT(tuple);
2924
2925 /* Sanity check. */
2926 Assert(list_length(node->args) == 2);
2927
2928 /* Always parenthesize the expression. */
2929 appendStringInfoChar(buf, '(');
2930
2931 /* Deparse left operand. */
2932 arg1 = linitial(node->args);
2933 deparseExpr(arg1, context);
2934 appendStringInfoChar(buf, ' ');
2935
2936 /* Deparse operator name plus decoration. */
2937 deparseOperatorName(buf, form);
2938 appendStringInfo(buf, " %s (", node->useOr ? "ANY" : "ALL");
2939
2940 /* Deparse right operand. */
2941 arg2 = lsecond(node->args);
2942 deparseExpr(arg2, context);
2943
2944 appendStringInfoChar(buf, ')');
2945
2946 /* Always parenthesize the expression. */
2947 appendStringInfoChar(buf, ')');
2948
2949 ReleaseSysCache(tuple);
2950 }
2951
2952 /*
2953 * Deparse a RelabelType (binary-compatible cast) node.
2954 */
2955 static void
deparseRelabelType(RelabelType * node,deparse_expr_cxt * context)2956 deparseRelabelType(RelabelType *node, deparse_expr_cxt *context)
2957 {
2958 deparseExpr(node->arg, context);
2959 if (node->relabelformat != COERCE_IMPLICIT_CAST)
2960 appendStringInfo(context->buf, "::%s",
2961 deparse_type_name(node->resulttype,
2962 node->resulttypmod));
2963 }
2964
2965 /*
2966 * Deparse a BoolExpr node.
2967 */
2968 static void
deparseBoolExpr(BoolExpr * node,deparse_expr_cxt * context)2969 deparseBoolExpr(BoolExpr *node, deparse_expr_cxt *context)
2970 {
2971 StringInfo buf = context->buf;
2972 const char *op = NULL; /* keep compiler quiet */
2973 bool first;
2974 ListCell *lc;
2975
2976 switch (node->boolop)
2977 {
2978 case AND_EXPR:
2979 op = "AND";
2980 break;
2981 case OR_EXPR:
2982 op = "OR";
2983 break;
2984 case NOT_EXPR:
2985 appendStringInfoString(buf, "(NOT ");
2986 deparseExpr(linitial(node->args), context);
2987 appendStringInfoChar(buf, ')');
2988 return;
2989 }
2990
2991 appendStringInfoChar(buf, '(');
2992 first = true;
2993 foreach(lc, node->args)
2994 {
2995 if (!first)
2996 appendStringInfo(buf, " %s ", op);
2997 deparseExpr((Expr *) lfirst(lc), context);
2998 first = false;
2999 }
3000 appendStringInfoChar(buf, ')');
3001 }
3002
3003 /*
3004 * Deparse IS [NOT] NULL expression.
3005 */
3006 static void
deparseNullTest(NullTest * node,deparse_expr_cxt * context)3007 deparseNullTest(NullTest *node, deparse_expr_cxt *context)
3008 {
3009 StringInfo buf = context->buf;
3010
3011 appendStringInfoChar(buf, '(');
3012 deparseExpr(node->arg, context);
3013
3014 /*
3015 * For scalar inputs, we prefer to print as IS [NOT] NULL, which is
3016 * shorter and traditional. If it's a rowtype input but we're applying a
3017 * scalar test, must print IS [NOT] DISTINCT FROM NULL to be semantically
3018 * correct.
3019 */
3020 if (node->argisrow || !type_is_rowtype(exprType((Node *) node->arg)))
3021 {
3022 if (node->nulltesttype == IS_NULL)
3023 appendStringInfoString(buf, " IS NULL)");
3024 else
3025 appendStringInfoString(buf, " IS NOT NULL)");
3026 }
3027 else
3028 {
3029 if (node->nulltesttype == IS_NULL)
3030 appendStringInfoString(buf, " IS NOT DISTINCT FROM NULL)");
3031 else
3032 appendStringInfoString(buf, " IS DISTINCT FROM NULL)");
3033 }
3034 }
3035
3036 /*
3037 * Deparse ARRAY[...] construct.
3038 */
3039 static void
deparseArrayExpr(ArrayExpr * node,deparse_expr_cxt * context)3040 deparseArrayExpr(ArrayExpr *node, deparse_expr_cxt *context)
3041 {
3042 StringInfo buf = context->buf;
3043 bool first = true;
3044 ListCell *lc;
3045
3046 appendStringInfoString(buf, "ARRAY[");
3047 foreach(lc, node->elements)
3048 {
3049 if (!first)
3050 appendStringInfoString(buf, ", ");
3051 deparseExpr(lfirst(lc), context);
3052 first = false;
3053 }
3054 appendStringInfoChar(buf, ']');
3055
3056 /* If the array is empty, we need an explicit cast to the array type. */
3057 if (node->elements == NIL)
3058 appendStringInfo(buf, "::%s",
3059 deparse_type_name(node->array_typeid, -1));
3060 }
3061
3062 /*
3063 * Deparse an Aggref node.
3064 */
3065 static void
deparseAggref(Aggref * node,deparse_expr_cxt * context)3066 deparseAggref(Aggref *node, deparse_expr_cxt *context)
3067 {
3068 StringInfo buf = context->buf;
3069 bool use_variadic;
3070
3071 /* Only basic, non-split aggregation accepted. */
3072 Assert(node->aggsplit == AGGSPLIT_SIMPLE);
3073
3074 /* Check if need to print VARIADIC (cf. ruleutils.c) */
3075 use_variadic = node->aggvariadic;
3076
3077 /* Find aggregate name from aggfnoid which is a pg_proc entry */
3078 appendFunctionName(node->aggfnoid, context);
3079 appendStringInfoChar(buf, '(');
3080
3081 /* Add DISTINCT */
3082 appendStringInfoString(buf, (node->aggdistinct != NIL) ? "DISTINCT " : "");
3083
3084 if (AGGKIND_IS_ORDERED_SET(node->aggkind))
3085 {
3086 /* Add WITHIN GROUP (ORDER BY ..) */
3087 ListCell *arg;
3088 bool first = true;
3089
3090 Assert(!node->aggvariadic);
3091 Assert(node->aggorder != NIL);
3092
3093 foreach(arg, node->aggdirectargs)
3094 {
3095 if (!first)
3096 appendStringInfoString(buf, ", ");
3097 first = false;
3098
3099 deparseExpr((Expr *) lfirst(arg), context);
3100 }
3101
3102 appendStringInfoString(buf, ") WITHIN GROUP (ORDER BY ");
3103 appendAggOrderBy(node->aggorder, node->args, context);
3104 }
3105 else
3106 {
3107 /* aggstar can be set only in zero-argument aggregates */
3108 if (node->aggstar)
3109 appendStringInfoChar(buf, '*');
3110 else
3111 {
3112 ListCell *arg;
3113 bool first = true;
3114
3115 /* Add all the arguments */
3116 foreach(arg, node->args)
3117 {
3118 TargetEntry *tle = (TargetEntry *) lfirst(arg);
3119 Node *n = (Node *) tle->expr;
3120
3121 if (tle->resjunk)
3122 continue;
3123
3124 if (!first)
3125 appendStringInfoString(buf, ", ");
3126 first = false;
3127
3128 /* Add VARIADIC */
3129 if (use_variadic && lnext(node->args, arg) == NULL)
3130 appendStringInfoString(buf, "VARIADIC ");
3131
3132 deparseExpr((Expr *) n, context);
3133 }
3134 }
3135
3136 /* Add ORDER BY */
3137 if (node->aggorder != NIL)
3138 {
3139 appendStringInfoString(buf, " ORDER BY ");
3140 appendAggOrderBy(node->aggorder, node->args, context);
3141 }
3142 }
3143
3144 /* Add FILTER (WHERE ..) */
3145 if (node->aggfilter != NULL)
3146 {
3147 appendStringInfoString(buf, ") FILTER (WHERE ");
3148 deparseExpr((Expr *) node->aggfilter, context);
3149 }
3150
3151 appendStringInfoChar(buf, ')');
3152 }
3153
3154 /*
3155 * Append ORDER BY within aggregate function.
3156 */
3157 static void
appendAggOrderBy(List * orderList,List * targetList,deparse_expr_cxt * context)3158 appendAggOrderBy(List *orderList, List *targetList, deparse_expr_cxt *context)
3159 {
3160 StringInfo buf = context->buf;
3161 ListCell *lc;
3162 bool first = true;
3163
3164 foreach(lc, orderList)
3165 {
3166 SortGroupClause *srt = (SortGroupClause *) lfirst(lc);
3167 Node *sortexpr;
3168 Oid sortcoltype;
3169 TypeCacheEntry *typentry;
3170
3171 if (!first)
3172 appendStringInfoString(buf, ", ");
3173 first = false;
3174
3175 sortexpr = deparseSortGroupClause(srt->tleSortGroupRef, targetList,
3176 false, context);
3177 sortcoltype = exprType(sortexpr);
3178 /* See whether operator is default < or > for datatype */
3179 typentry = lookup_type_cache(sortcoltype,
3180 TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
3181 if (srt->sortop == typentry->lt_opr)
3182 appendStringInfoString(buf, " ASC");
3183 else if (srt->sortop == typentry->gt_opr)
3184 appendStringInfoString(buf, " DESC");
3185 else
3186 {
3187 HeapTuple opertup;
3188 Form_pg_operator operform;
3189
3190 appendStringInfoString(buf, " USING ");
3191
3192 /* Append operator name. */
3193 opertup = SearchSysCache1(OPEROID, ObjectIdGetDatum(srt->sortop));
3194 if (!HeapTupleIsValid(opertup))
3195 elog(ERROR, "cache lookup failed for operator %u", srt->sortop);
3196 operform = (Form_pg_operator) GETSTRUCT(opertup);
3197 deparseOperatorName(buf, operform);
3198 ReleaseSysCache(opertup);
3199 }
3200
3201 if (srt->nulls_first)
3202 appendStringInfoString(buf, " NULLS FIRST");
3203 else
3204 appendStringInfoString(buf, " NULLS LAST");
3205 }
3206 }
3207
3208 /*
3209 * Print the representation of a parameter to be sent to the remote side.
3210 *
3211 * Note: we always label the Param's type explicitly rather than relying on
3212 * transmitting a numeric type OID in PQexecParams(). This allows us to
3213 * avoid assuming that types have the same OIDs on the remote side as they
3214 * do locally --- they need only have the same names.
3215 */
3216 static void
printRemoteParam(int paramindex,Oid paramtype,int32 paramtypmod,deparse_expr_cxt * context)3217 printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod,
3218 deparse_expr_cxt *context)
3219 {
3220 StringInfo buf = context->buf;
3221 char *ptypename = deparse_type_name(paramtype, paramtypmod);
3222
3223 appendStringInfo(buf, "$%d::%s", paramindex, ptypename);
3224 }
3225
3226 /*
3227 * Print the representation of a placeholder for a parameter that will be
3228 * sent to the remote side at execution time.
3229 *
3230 * This is used when we're just trying to EXPLAIN the remote query.
3231 * We don't have the actual value of the runtime parameter yet, and we don't
3232 * want the remote planner to generate a plan that depends on such a value
3233 * anyway. Thus, we can't do something simple like "$1::paramtype".
3234 * Instead, we emit "((SELECT null::paramtype)::paramtype)".
3235 * In all extant versions of Postgres, the planner will see that as an unknown
3236 * constant value, which is what we want. This might need adjustment if we
3237 * ever make the planner flatten scalar subqueries. Note: the reason for the
3238 * apparently useless outer cast is to ensure that the representation as a
3239 * whole will be parsed as an a_expr and not a select_with_parens; the latter
3240 * would do the wrong thing in the context "x = ANY(...)".
3241 */
3242 static void
printRemotePlaceholder(Oid paramtype,int32 paramtypmod,deparse_expr_cxt * context)3243 printRemotePlaceholder(Oid paramtype, int32 paramtypmod,
3244 deparse_expr_cxt *context)
3245 {
3246 StringInfo buf = context->buf;
3247 char *ptypename = deparse_type_name(paramtype, paramtypmod);
3248
3249 appendStringInfo(buf, "((SELECT null::%s)::%s)", ptypename, ptypename);
3250 }
3251
3252 /*
3253 * Deparse GROUP BY clause.
3254 */
3255 static void
appendGroupByClause(List * tlist,deparse_expr_cxt * context)3256 appendGroupByClause(List *tlist, deparse_expr_cxt *context)
3257 {
3258 StringInfo buf = context->buf;
3259 Query *query = context->root->parse;
3260 ListCell *lc;
3261 bool first = true;
3262
3263 /* Nothing to be done, if there's no GROUP BY clause in the query. */
3264 if (!query->groupClause)
3265 return;
3266
3267 appendStringInfoString(buf, " GROUP BY ");
3268
3269 /*
3270 * Queries with grouping sets are not pushed down, so we don't expect
3271 * grouping sets here.
3272 */
3273 Assert(!query->groupingSets);
3274
3275 foreach(lc, query->groupClause)
3276 {
3277 SortGroupClause *grp = (SortGroupClause *) lfirst(lc);
3278
3279 if (!first)
3280 appendStringInfoString(buf, ", ");
3281 first = false;
3282
3283 deparseSortGroupClause(grp->tleSortGroupRef, tlist, true, context);
3284 }
3285 }
3286
3287 /*
3288 * Deparse ORDER BY clause according to the given pathkeys for given base
3289 * relation. From given pathkeys expressions belonging entirely to the given
3290 * base relation are obtained and deparsed.
3291 */
3292 static void
appendOrderByClause(List * pathkeys,bool has_final_sort,deparse_expr_cxt * context)3293 appendOrderByClause(List *pathkeys, bool has_final_sort,
3294 deparse_expr_cxt *context)
3295 {
3296 ListCell *lcell;
3297 int nestlevel;
3298 char *delim = " ";
3299 RelOptInfo *baserel = context->scanrel;
3300 StringInfo buf = context->buf;
3301
3302 /* Make sure any constants in the exprs are printed portably */
3303 nestlevel = set_transmission_modes();
3304
3305 appendStringInfoString(buf, " ORDER BY");
3306 foreach(lcell, pathkeys)
3307 {
3308 PathKey *pathkey = lfirst(lcell);
3309 Expr *em_expr;
3310
3311 if (has_final_sort)
3312 {
3313 /*
3314 * By construction, context->foreignrel is the input relation to
3315 * the final sort.
3316 */
3317 em_expr = find_em_expr_for_input_target(context->root,
3318 pathkey->pk_eclass,
3319 context->foreignrel->reltarget);
3320 }
3321 else
3322 em_expr = find_em_expr_for_rel(pathkey->pk_eclass, baserel);
3323
3324 Assert(em_expr != NULL);
3325
3326 appendStringInfoString(buf, delim);
3327 deparseExpr(em_expr, context);
3328 if (pathkey->pk_strategy == BTLessStrategyNumber)
3329 appendStringInfoString(buf, " ASC");
3330 else
3331 appendStringInfoString(buf, " DESC");
3332
3333 if (pathkey->pk_nulls_first)
3334 appendStringInfoString(buf, " NULLS FIRST");
3335 else
3336 appendStringInfoString(buf, " NULLS LAST");
3337
3338 delim = ", ";
3339 }
3340 reset_transmission_modes(nestlevel);
3341 }
3342
3343 /*
3344 * Deparse LIMIT/OFFSET clause.
3345 */
3346 static void
appendLimitClause(deparse_expr_cxt * context)3347 appendLimitClause(deparse_expr_cxt *context)
3348 {
3349 PlannerInfo *root = context->root;
3350 StringInfo buf = context->buf;
3351 int nestlevel;
3352
3353 /* Make sure any constants in the exprs are printed portably */
3354 nestlevel = set_transmission_modes();
3355
3356 if (root->parse->limitCount)
3357 {
3358 appendStringInfoString(buf, " LIMIT ");
3359 deparseExpr((Expr *) root->parse->limitCount, context);
3360 }
3361 if (root->parse->limitOffset)
3362 {
3363 appendStringInfoString(buf, " OFFSET ");
3364 deparseExpr((Expr *) root->parse->limitOffset, context);
3365 }
3366
3367 reset_transmission_modes(nestlevel);
3368 }
3369
3370 /*
3371 * appendFunctionName
3372 * Deparses function name from given function oid.
3373 */
3374 static void
appendFunctionName(Oid funcid,deparse_expr_cxt * context)3375 appendFunctionName(Oid funcid, deparse_expr_cxt *context)
3376 {
3377 StringInfo buf = context->buf;
3378 HeapTuple proctup;
3379 Form_pg_proc procform;
3380 const char *proname;
3381
3382 proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
3383 if (!HeapTupleIsValid(proctup))
3384 elog(ERROR, "cache lookup failed for function %u", funcid);
3385 procform = (Form_pg_proc) GETSTRUCT(proctup);
3386
3387 /* Print schema name only if it's not pg_catalog */
3388 if (procform->pronamespace != PG_CATALOG_NAMESPACE)
3389 {
3390 const char *schemaname;
3391
3392 schemaname = get_namespace_name(procform->pronamespace);
3393 appendStringInfo(buf, "%s.", quote_identifier(schemaname));
3394 }
3395
3396 /* Always print the function name */
3397 proname = NameStr(procform->proname);
3398 appendStringInfoString(buf, quote_identifier(proname));
3399
3400 ReleaseSysCache(proctup);
3401 }
3402
3403 /*
3404 * Appends a sort or group clause.
3405 *
3406 * Like get_rule_sortgroupclause(), returns the expression tree, so caller
3407 * need not find it again.
3408 */
3409 static Node *
deparseSortGroupClause(Index ref,List * tlist,bool force_colno,deparse_expr_cxt * context)3410 deparseSortGroupClause(Index ref, List *tlist, bool force_colno,
3411 deparse_expr_cxt *context)
3412 {
3413 StringInfo buf = context->buf;
3414 TargetEntry *tle;
3415 Expr *expr;
3416
3417 tle = get_sortgroupref_tle(ref, tlist);
3418 expr = tle->expr;
3419
3420 if (force_colno)
3421 {
3422 /* Use column-number form when requested by caller. */
3423 Assert(!tle->resjunk);
3424 appendStringInfo(buf, "%d", tle->resno);
3425 }
3426 else if (expr && IsA(expr, Const))
3427 {
3428 /*
3429 * Force a typecast here so that we don't emit something like "GROUP
3430 * BY 2", which will be misconstrued as a column position rather than
3431 * a constant.
3432 */
3433 deparseConst((Const *) expr, context, 1);
3434 }
3435 else if (!expr || IsA(expr, Var))
3436 deparseExpr(expr, context);
3437 else
3438 {
3439 /* Always parenthesize the expression. */
3440 appendStringInfoChar(buf, '(');
3441 deparseExpr(expr, context);
3442 appendStringInfoChar(buf, ')');
3443 }
3444
3445 return (Node *) expr;
3446 }
3447
3448
3449 /*
3450 * Returns true if given Var is deparsed as a subquery output column, in
3451 * which case, *relno and *colno are set to the IDs for the relation and
3452 * column alias to the Var provided by the subquery.
3453 */
3454 static bool
is_subquery_var(Var * node,RelOptInfo * foreignrel,int * relno,int * colno)3455 is_subquery_var(Var *node, RelOptInfo *foreignrel, int *relno, int *colno)
3456 {
3457 PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
3458 RelOptInfo *outerrel = fpinfo->outerrel;
3459 RelOptInfo *innerrel = fpinfo->innerrel;
3460
3461 /* Should only be called in these cases. */
3462 Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel));
3463
3464 /*
3465 * If the given relation isn't a join relation, it doesn't have any lower
3466 * subqueries, so the Var isn't a subquery output column.
3467 */
3468 if (!IS_JOIN_REL(foreignrel))
3469 return false;
3470
3471 /*
3472 * If the Var doesn't belong to any lower subqueries, it isn't a subquery
3473 * output column.
3474 */
3475 if (!bms_is_member(node->varno, fpinfo->lower_subquery_rels))
3476 return false;
3477
3478 if (bms_is_member(node->varno, outerrel->relids))
3479 {
3480 /*
3481 * If outer relation is deparsed as a subquery, the Var is an output
3482 * column of the subquery; get the IDs for the relation/column alias.
3483 */
3484 if (fpinfo->make_outerrel_subquery)
3485 {
3486 get_relation_column_alias_ids(node, outerrel, relno, colno);
3487 return true;
3488 }
3489
3490 /* Otherwise, recurse into the outer relation. */
3491 return is_subquery_var(node, outerrel, relno, colno);
3492 }
3493 else
3494 {
3495 Assert(bms_is_member(node->varno, innerrel->relids));
3496
3497 /*
3498 * If inner relation is deparsed as a subquery, the Var is an output
3499 * column of the subquery; get the IDs for the relation/column alias.
3500 */
3501 if (fpinfo->make_innerrel_subquery)
3502 {
3503 get_relation_column_alias_ids(node, innerrel, relno, colno);
3504 return true;
3505 }
3506
3507 /* Otherwise, recurse into the inner relation. */
3508 return is_subquery_var(node, innerrel, relno, colno);
3509 }
3510 }
3511
3512 /*
3513 * Get the IDs for the relation and column alias to given Var belonging to
3514 * given relation, which are returned into *relno and *colno.
3515 */
3516 static void
get_relation_column_alias_ids(Var * node,RelOptInfo * foreignrel,int * relno,int * colno)3517 get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
3518 int *relno, int *colno)
3519 {
3520 PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
3521 int i;
3522 ListCell *lc;
3523
3524 /* Get the relation alias ID */
3525 *relno = fpinfo->relation_index;
3526
3527 /* Get the column alias ID */
3528 i = 1;
3529 foreach(lc, foreignrel->reltarget->exprs)
3530 {
3531 if (equal(lfirst(lc), (Node *) node))
3532 {
3533 *colno = i;
3534 return;
3535 }
3536 i++;
3537 }
3538
3539 /* Shouldn't get here */
3540 elog(ERROR, "unexpected expression in subquery output");
3541 }
3542