1 /*-------------------------------------------------------------------------
2 *
3 * functions.c
4 * Execution of SQL-language functions
5 *
6 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/executor/functions.c
12 *
13 *-------------------------------------------------------------------------
14 */
15 #include "postgres.h"
16
17 #include "access/htup_details.h"
18 #include "access/xact.h"
19 #include "catalog/pg_proc.h"
20 #include "catalog/pg_type.h"
21 #include "executor/functions.h"
22 #include "funcapi.h"
23 #include "miscadmin.h"
24 #include "nodes/makefuncs.h"
25 #include "nodes/nodeFuncs.h"
26 #include "parser/parse_coerce.h"
27 #include "parser/parse_func.h"
28 #include "storage/proc.h"
29 #include "tcop/utility.h"
30 #include "utils/builtins.h"
31 #include "utils/datum.h"
32 #include "utils/lsyscache.h"
33 #include "utils/memutils.h"
34 #include "utils/snapmgr.h"
35 #include "utils/syscache.h"
36
37
38 /*
39 * Specialized DestReceiver for collecting query output in a SQL function
40 */
41 typedef struct
42 {
43 DestReceiver pub; /* publicly-known function pointers */
44 Tuplestorestate *tstore; /* where to put result tuples */
45 MemoryContext cxt; /* context containing tstore */
46 JunkFilter *filter; /* filter to convert tuple type */
47 } DR_sqlfunction;
48
49 /*
50 * We have an execution_state record for each query in a function. Each
51 * record contains a plantree for its query. If the query is currently in
52 * F_EXEC_RUN state then there's a QueryDesc too.
53 *
54 * The "next" fields chain together all the execution_state records generated
55 * from a single original parsetree. (There will only be more than one in
56 * case of rule expansion of the original parsetree.)
57 */
58 typedef enum
59 {
60 F_EXEC_START, F_EXEC_RUN, F_EXEC_DONE
61 } ExecStatus;
62
63 typedef struct execution_state
64 {
65 struct execution_state *next;
66 ExecStatus status;
67 bool setsResult; /* true if this query produces func's result */
68 bool lazyEval; /* true if should fetch one row at a time */
69 PlannedStmt *stmt; /* plan for this query */
70 QueryDesc *qd; /* null unless status == RUN */
71 } execution_state;
72
73
74 /*
75 * An SQLFunctionCache record is built during the first call,
76 * and linked to from the fn_extra field of the FmgrInfo struct.
77 *
78 * Note that currently this has only the lifespan of the calling query.
79 * Someday we should rewrite this code to use plancache.c to save parse/plan
80 * results for longer than that.
81 *
82 * Physically, though, the data has the lifespan of the FmgrInfo that's used
83 * to call the function, and there are cases (particularly with indexes)
84 * where the FmgrInfo might survive across transactions. We cannot assume
85 * that the parse/plan trees are good for longer than the (sub)transaction in
86 * which parsing was done, so we must mark the record with the LXID/subxid of
87 * its creation time, and regenerate everything if that's obsolete. To avoid
88 * memory leakage when we do have to regenerate things, all the data is kept
89 * in a sub-context of the FmgrInfo's fn_mcxt.
90 */
91 typedef struct
92 {
93 char *fname; /* function name (for error msgs) */
94 char *src; /* function body text (for error msgs) */
95
96 SQLFunctionParseInfoPtr pinfo; /* data for parser callback hooks */
97
98 Oid rettype; /* actual return type */
99 int16 typlen; /* length of the return type */
100 bool typbyval; /* true if return type is pass by value */
101 bool returnsSet; /* true if returning multiple rows */
102 bool returnsTuple; /* true if returning whole tuple result */
103 bool shutdown_reg; /* true if registered shutdown callback */
104 bool readonly_func; /* true to run in "read only" mode */
105 bool lazyEval; /* true if using lazyEval for result query */
106
107 ParamListInfo paramLI; /* Param list representing current args */
108
109 Tuplestorestate *tstore; /* where we accumulate result tuples */
110
111 JunkFilter *junkFilter; /* will be NULL if function returns VOID */
112
113 /*
114 * func_state is a List of execution_state records, each of which is the
115 * first for its original parsetree, with any additional records chained
116 * to it via the "next" fields. This sublist structure is needed to keep
117 * track of where the original query boundaries are.
118 */
119 List *func_state;
120
121 MemoryContext fcontext; /* memory context holding this struct and all
122 * subsidiary data */
123
124 LocalTransactionId lxid; /* lxid in which cache was made */
125 SubTransactionId subxid; /* subxid in which cache was made */
126 } SQLFunctionCache;
127
128 typedef SQLFunctionCache *SQLFunctionCachePtr;
129
130 /*
131 * Data structure needed by the parser callback hooks to resolve parameter
132 * references during parsing of a SQL function's body. This is separate from
133 * SQLFunctionCache since we sometimes do parsing separately from execution.
134 */
135 typedef struct SQLFunctionParseInfo
136 {
137 char *fname; /* function's name */
138 int nargs; /* number of input arguments */
139 Oid *argtypes; /* resolved types of input arguments */
140 char **argnames; /* names of input arguments; NULL if none */
141 /* Note that argnames[i] can be NULL, if some args are unnamed */
142 Oid collation; /* function's input collation, if known */
143 } SQLFunctionParseInfo;
144
145
146 /* non-export function prototypes */
147 static Node *sql_fn_param_ref(ParseState *pstate, ParamRef *pref);
148 static Node *sql_fn_post_column_ref(ParseState *pstate,
149 ColumnRef *cref, Node *var);
150 static Node *sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,
151 int paramno, int location);
152 static Node *sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,
153 const char *paramname, int location);
154 static List *init_execution_state(List *queryTree_list,
155 SQLFunctionCachePtr fcache,
156 bool lazyEvalOK);
157 static void init_sql_fcache(FmgrInfo *finfo, Oid collation, bool lazyEvalOK);
158 static void postquel_start(execution_state *es, SQLFunctionCachePtr fcache);
159 static bool postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache);
160 static void postquel_end(execution_state *es);
161 static void postquel_sub_params(SQLFunctionCachePtr fcache,
162 FunctionCallInfo fcinfo);
163 static Datum postquel_get_single_result(TupleTableSlot *slot,
164 FunctionCallInfo fcinfo,
165 SQLFunctionCachePtr fcache,
166 MemoryContext resultcontext);
167 static void sql_exec_error_callback(void *arg);
168 static void ShutdownSQLFunction(Datum arg);
169 static void sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
170 static bool sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self);
171 static void sqlfunction_shutdown(DestReceiver *self);
172 static void sqlfunction_destroy(DestReceiver *self);
173
174
175 /*
176 * Prepare the SQLFunctionParseInfo struct for parsing a SQL function body
177 *
178 * This includes resolving actual types of polymorphic arguments.
179 *
180 * call_expr can be passed as NULL, but then we will fail if there are any
181 * polymorphic arguments.
182 */
183 SQLFunctionParseInfoPtr
prepare_sql_fn_parse_info(HeapTuple procedureTuple,Node * call_expr,Oid inputCollation)184 prepare_sql_fn_parse_info(HeapTuple procedureTuple,
185 Node *call_expr,
186 Oid inputCollation)
187 {
188 SQLFunctionParseInfoPtr pinfo;
189 Form_pg_proc procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
190 int nargs;
191
192 pinfo = (SQLFunctionParseInfoPtr) palloc0(sizeof(SQLFunctionParseInfo));
193
194 /* Function's name (only) can be used to qualify argument names */
195 pinfo->fname = pstrdup(NameStr(procedureStruct->proname));
196
197 /* Save the function's input collation */
198 pinfo->collation = inputCollation;
199
200 /*
201 * Copy input argument types from the pg_proc entry, then resolve any
202 * polymorphic types.
203 */
204 pinfo->nargs = nargs = procedureStruct->pronargs;
205 if (nargs > 0)
206 {
207 Oid *argOidVect;
208 int argnum;
209
210 argOidVect = (Oid *) palloc(nargs * sizeof(Oid));
211 memcpy(argOidVect,
212 procedureStruct->proargtypes.values,
213 nargs * sizeof(Oid));
214
215 for (argnum = 0; argnum < nargs; argnum++)
216 {
217 Oid argtype = argOidVect[argnum];
218
219 if (IsPolymorphicType(argtype))
220 {
221 argtype = get_call_expr_argtype(call_expr, argnum);
222 if (argtype == InvalidOid)
223 ereport(ERROR,
224 (errcode(ERRCODE_DATATYPE_MISMATCH),
225 errmsg("could not determine actual type of argument declared %s",
226 format_type_be(argOidVect[argnum]))));
227 argOidVect[argnum] = argtype;
228 }
229 }
230
231 pinfo->argtypes = argOidVect;
232 }
233
234 /*
235 * Collect names of arguments, too, if any
236 */
237 if (nargs > 0)
238 {
239 Datum proargnames;
240 Datum proargmodes;
241 int n_arg_names;
242 bool isNull;
243
244 proargnames = SysCacheGetAttr(PROCNAMEARGSNSP, procedureTuple,
245 Anum_pg_proc_proargnames,
246 &isNull);
247 if (isNull)
248 proargnames = PointerGetDatum(NULL); /* just to be sure */
249
250 proargmodes = SysCacheGetAttr(PROCNAMEARGSNSP, procedureTuple,
251 Anum_pg_proc_proargmodes,
252 &isNull);
253 if (isNull)
254 proargmodes = PointerGetDatum(NULL); /* just to be sure */
255
256 n_arg_names = get_func_input_arg_names(proargnames, proargmodes,
257 &pinfo->argnames);
258
259 /* Paranoia: ignore the result if too few array entries */
260 if (n_arg_names < nargs)
261 pinfo->argnames = NULL;
262 }
263 else
264 pinfo->argnames = NULL;
265
266 return pinfo;
267 }
268
269 /*
270 * Parser setup hook for parsing a SQL function body.
271 */
272 void
sql_fn_parser_setup(struct ParseState * pstate,SQLFunctionParseInfoPtr pinfo)273 sql_fn_parser_setup(struct ParseState *pstate, SQLFunctionParseInfoPtr pinfo)
274 {
275 pstate->p_pre_columnref_hook = NULL;
276 pstate->p_post_columnref_hook = sql_fn_post_column_ref;
277 pstate->p_paramref_hook = sql_fn_param_ref;
278 /* no need to use p_coerce_param_hook */
279 pstate->p_ref_hook_state = (void *) pinfo;
280 }
281
282 /*
283 * sql_fn_post_column_ref parser callback for ColumnRefs
284 */
285 static Node *
sql_fn_post_column_ref(ParseState * pstate,ColumnRef * cref,Node * var)286 sql_fn_post_column_ref(ParseState *pstate, ColumnRef *cref, Node *var)
287 {
288 SQLFunctionParseInfoPtr pinfo = (SQLFunctionParseInfoPtr) pstate->p_ref_hook_state;
289 int nnames;
290 Node *field1;
291 Node *subfield = NULL;
292 const char *name1;
293 const char *name2 = NULL;
294 Node *param;
295
296 /*
297 * Never override a table-column reference. This corresponds to
298 * considering the parameter names to appear in a scope outside the
299 * individual SQL commands, which is what we want.
300 */
301 if (var != NULL)
302 return NULL;
303
304 /*----------
305 * The allowed syntaxes are:
306 *
307 * A A = parameter name
308 * A.B A = function name, B = parameter name
309 * OR: A = record-typed parameter name, B = field name
310 * (the first possibility takes precedence)
311 * A.B.C A = function name, B = record-typed parameter name,
312 * C = field name
313 * A.* Whole-row reference to composite parameter A.
314 * A.B.* Same, with A = function name, B = parameter name
315 *
316 * Here, it's sufficient to ignore the "*" in the last two cases --- the
317 * main parser will take care of expanding the whole-row reference.
318 *----------
319 */
320 nnames = list_length(cref->fields);
321
322 if (nnames > 3)
323 return NULL;
324
325 if (IsA(llast(cref->fields), A_Star))
326 nnames--;
327
328 field1 = (Node *) linitial(cref->fields);
329 Assert(IsA(field1, String));
330 name1 = strVal(field1);
331 if (nnames > 1)
332 {
333 subfield = (Node *) lsecond(cref->fields);
334 Assert(IsA(subfield, String));
335 name2 = strVal(subfield);
336 }
337
338 if (nnames == 3)
339 {
340 /*
341 * Three-part name: if the first part doesn't match the function name,
342 * we can fail immediately. Otherwise, look up the second part, and
343 * take the third part to be a field reference.
344 */
345 if (strcmp(name1, pinfo->fname) != 0)
346 return NULL;
347
348 param = sql_fn_resolve_param_name(pinfo, name2, cref->location);
349
350 subfield = (Node *) lthird(cref->fields);
351 Assert(IsA(subfield, String));
352 }
353 else if (nnames == 2 && strcmp(name1, pinfo->fname) == 0)
354 {
355 /*
356 * Two-part name with first part matching function name: first see if
357 * second part matches any parameter name.
358 */
359 param = sql_fn_resolve_param_name(pinfo, name2, cref->location);
360
361 if (param)
362 {
363 /* Yes, so this is a parameter reference, no subfield */
364 subfield = NULL;
365 }
366 else
367 {
368 /* No, so try to match as parameter name and subfield */
369 param = sql_fn_resolve_param_name(pinfo, name1, cref->location);
370 }
371 }
372 else
373 {
374 /* Single name, or parameter name followed by subfield */
375 param = sql_fn_resolve_param_name(pinfo, name1, cref->location);
376 }
377
378 if (!param)
379 return NULL; /* No match */
380
381 if (subfield)
382 {
383 /*
384 * Must be a reference to a field of a composite parameter; otherwise
385 * ParseFuncOrColumn will return NULL, and we'll fail back at the
386 * caller.
387 */
388 param = ParseFuncOrColumn(pstate,
389 list_make1(subfield),
390 list_make1(param),
391 pstate->p_last_srf,
392 NULL,
393 cref->location);
394 }
395
396 return param;
397 }
398
399 /*
400 * sql_fn_param_ref parser callback for ParamRefs ($n symbols)
401 */
402 static Node *
sql_fn_param_ref(ParseState * pstate,ParamRef * pref)403 sql_fn_param_ref(ParseState *pstate, ParamRef *pref)
404 {
405 SQLFunctionParseInfoPtr pinfo = (SQLFunctionParseInfoPtr) pstate->p_ref_hook_state;
406 int paramno = pref->number;
407
408 /* Check parameter number is valid */
409 if (paramno <= 0 || paramno > pinfo->nargs)
410 return NULL; /* unknown parameter number */
411
412 return sql_fn_make_param(pinfo, paramno, pref->location);
413 }
414
415 /*
416 * sql_fn_make_param construct a Param node for the given paramno
417 */
418 static Node *
sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,int paramno,int location)419 sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,
420 int paramno, int location)
421 {
422 Param *param;
423
424 param = makeNode(Param);
425 param->paramkind = PARAM_EXTERN;
426 param->paramid = paramno;
427 param->paramtype = pinfo->argtypes[paramno - 1];
428 param->paramtypmod = -1;
429 param->paramcollid = get_typcollation(param->paramtype);
430 param->location = location;
431
432 /*
433 * If we have a function input collation, allow it to override the
434 * type-derived collation for parameter symbols. (XXX perhaps this should
435 * not happen if the type collation is not default?)
436 */
437 if (OidIsValid(pinfo->collation) && OidIsValid(param->paramcollid))
438 param->paramcollid = pinfo->collation;
439
440 return (Node *) param;
441 }
442
443 /*
444 * Search for a function parameter of the given name; if there is one,
445 * construct and return a Param node for it. If not, return NULL.
446 * Helper function for sql_fn_post_column_ref.
447 */
448 static Node *
sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,const char * paramname,int location)449 sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,
450 const char *paramname, int location)
451 {
452 int i;
453
454 if (pinfo->argnames == NULL)
455 return NULL;
456
457 for (i = 0; i < pinfo->nargs; i++)
458 {
459 if (pinfo->argnames[i] && strcmp(pinfo->argnames[i], paramname) == 0)
460 return sql_fn_make_param(pinfo, i + 1, location);
461 }
462
463 return NULL;
464 }
465
466 /*
467 * Set up the per-query execution_state records for a SQL function.
468 *
469 * The input is a List of Lists of parsed and rewritten, but not planned,
470 * querytrees. The sublist structure denotes the original query boundaries.
471 */
472 static List *
init_execution_state(List * queryTree_list,SQLFunctionCachePtr fcache,bool lazyEvalOK)473 init_execution_state(List *queryTree_list,
474 SQLFunctionCachePtr fcache,
475 bool lazyEvalOK)
476 {
477 List *eslist = NIL;
478 execution_state *lasttages = NULL;
479 ListCell *lc1;
480
481 foreach(lc1, queryTree_list)
482 {
483 List *qtlist = lfirst_node(List, lc1);
484 execution_state *firstes = NULL;
485 execution_state *preves = NULL;
486 ListCell *lc2;
487
488 foreach(lc2, qtlist)
489 {
490 Query *queryTree = lfirst_node(Query, lc2);
491 PlannedStmt *stmt;
492 execution_state *newes;
493
494 /* Plan the query if needed */
495 if (queryTree->commandType == CMD_UTILITY)
496 {
497 /* Utility commands require no planning. */
498 stmt = makeNode(PlannedStmt);
499 stmt->commandType = CMD_UTILITY;
500 stmt->canSetTag = queryTree->canSetTag;
501 stmt->utilityStmt = queryTree->utilityStmt;
502 stmt->stmt_location = queryTree->stmt_location;
503 stmt->stmt_len = queryTree->stmt_len;
504 }
505 else
506 stmt = pg_plan_query(queryTree,
507 CURSOR_OPT_PARALLEL_OK,
508 NULL);
509
510 /*
511 * Precheck all commands for validity in a function. This should
512 * generally match the restrictions spi.c applies.
513 */
514 if (stmt->commandType == CMD_UTILITY)
515 {
516 if (IsA(stmt->utilityStmt, CopyStmt) &&
517 ((CopyStmt *) stmt->utilityStmt)->filename == NULL)
518 ereport(ERROR,
519 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
520 errmsg("cannot COPY to/from client in a SQL function")));
521
522 if (IsA(stmt->utilityStmt, TransactionStmt))
523 ereport(ERROR,
524 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
525 /* translator: %s is a SQL statement name */
526 errmsg("%s is not allowed in a SQL function",
527 CreateCommandTag(stmt->utilityStmt))));
528 }
529
530 if (fcache->readonly_func && !CommandIsReadOnly(stmt))
531 ereport(ERROR,
532 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
533 /* translator: %s is a SQL statement name */
534 errmsg("%s is not allowed in a non-volatile function",
535 CreateCommandTag((Node *) stmt))));
536
537 if (IsInParallelMode() && !CommandIsReadOnly(stmt))
538 PreventCommandIfParallelMode(CreateCommandTag((Node *) stmt));
539
540 /* OK, build the execution_state for this query */
541 newes = (execution_state *) palloc(sizeof(execution_state));
542 if (preves)
543 preves->next = newes;
544 else
545 firstes = newes;
546
547 newes->next = NULL;
548 newes->status = F_EXEC_START;
549 newes->setsResult = false; /* might change below */
550 newes->lazyEval = false; /* might change below */
551 newes->stmt = stmt;
552 newes->qd = NULL;
553
554 if (queryTree->canSetTag)
555 lasttages = newes;
556
557 preves = newes;
558 }
559
560 eslist = lappend(eslist, firstes);
561 }
562
563 /*
564 * Mark the last canSetTag query as delivering the function result; then,
565 * if it is a plain SELECT, mark it for lazy evaluation. If it's not a
566 * SELECT we must always run it to completion.
567 *
568 * Note: at some point we might add additional criteria for whether to use
569 * lazy eval. However, we should prefer to use it whenever the function
570 * doesn't return set, since fetching more than one row is useless in that
571 * case.
572 *
573 * Note: don't set setsResult if the function returns VOID, as evidenced
574 * by not having made a junkfilter. This ensures we'll throw away any
575 * output from a utility statement that check_sql_fn_retval deemed to not
576 * have output.
577 */
578 if (lasttages && fcache->junkFilter)
579 {
580 lasttages->setsResult = true;
581 if (lazyEvalOK &&
582 lasttages->stmt->commandType == CMD_SELECT &&
583 !lasttages->stmt->hasModifyingCTE)
584 fcache->lazyEval = lasttages->lazyEval = true;
585 }
586
587 return eslist;
588 }
589
590 /*
591 * Initialize the SQLFunctionCache for a SQL function
592 */
593 static void
init_sql_fcache(FmgrInfo * finfo,Oid collation,bool lazyEvalOK)594 init_sql_fcache(FmgrInfo *finfo, Oid collation, bool lazyEvalOK)
595 {
596 Oid foid = finfo->fn_oid;
597 MemoryContext fcontext;
598 MemoryContext oldcontext;
599 Oid rettype;
600 HeapTuple procedureTuple;
601 Form_pg_proc procedureStruct;
602 SQLFunctionCachePtr fcache;
603 List *raw_parsetree_list;
604 List *queryTree_list;
605 List *flat_query_list;
606 ListCell *lc;
607 Datum tmp;
608 bool isNull;
609
610 /*
611 * Create memory context that holds all the SQLFunctionCache data. It
612 * must be a child of whatever context holds the FmgrInfo.
613 */
614 fcontext = AllocSetContextCreate(finfo->fn_mcxt,
615 "SQL function data",
616 ALLOCSET_DEFAULT_SIZES);
617
618 oldcontext = MemoryContextSwitchTo(fcontext);
619
620 /*
621 * Create the struct proper, link it to fcontext and fn_extra. Once this
622 * is done, we'll be able to recover the memory after failure, even if the
623 * FmgrInfo is long-lived.
624 */
625 fcache = (SQLFunctionCachePtr) palloc0(sizeof(SQLFunctionCache));
626 fcache->fcontext = fcontext;
627 finfo->fn_extra = (void *) fcache;
628
629 /*
630 * get the procedure tuple corresponding to the given function Oid
631 */
632 procedureTuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(foid));
633 if (!HeapTupleIsValid(procedureTuple))
634 elog(ERROR, "cache lookup failed for function %u", foid);
635 procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
636
637 /*
638 * copy function name immediately for use by error reporting callback
639 */
640 fcache->fname = pstrdup(NameStr(procedureStruct->proname));
641
642 /*
643 * get the result type from the procedure tuple, and check for polymorphic
644 * result type; if so, find out the actual result type.
645 */
646 rettype = procedureStruct->prorettype;
647
648 if (IsPolymorphicType(rettype))
649 {
650 rettype = get_fn_expr_rettype(finfo);
651 if (rettype == InvalidOid) /* this probably should not happen */
652 ereport(ERROR,
653 (errcode(ERRCODE_DATATYPE_MISMATCH),
654 errmsg("could not determine actual result type for function declared to return type %s",
655 format_type_be(procedureStruct->prorettype))));
656 }
657
658 fcache->rettype = rettype;
659
660 /* Fetch the typlen and byval info for the result type */
661 get_typlenbyval(rettype, &fcache->typlen, &fcache->typbyval);
662
663 /* Remember whether we're returning setof something */
664 fcache->returnsSet = procedureStruct->proretset;
665
666 /* Remember if function is STABLE/IMMUTABLE */
667 fcache->readonly_func =
668 (procedureStruct->provolatile != PROVOLATILE_VOLATILE);
669
670 /*
671 * We need the actual argument types to pass to the parser. Also make
672 * sure that parameter symbols are considered to have the function's
673 * resolved input collation.
674 */
675 fcache->pinfo = prepare_sql_fn_parse_info(procedureTuple,
676 finfo->fn_expr,
677 collation);
678
679 /*
680 * And of course we need the function body text.
681 */
682 tmp = SysCacheGetAttr(PROCOID,
683 procedureTuple,
684 Anum_pg_proc_prosrc,
685 &isNull);
686 if (isNull)
687 elog(ERROR, "null prosrc for function %u", foid);
688 fcache->src = TextDatumGetCString(tmp);
689
690 /*
691 * Parse and rewrite the queries in the function text. Use sublists to
692 * keep track of the original query boundaries. But we also build a
693 * "flat" list of the rewritten queries to pass to check_sql_fn_retval.
694 * This is because the last canSetTag query determines the result type
695 * independently of query boundaries --- and it might not be in the last
696 * sublist, for example if the last query rewrites to DO INSTEAD NOTHING.
697 * (It might not be unreasonable to throw an error in such a case, but
698 * this is the historical behavior and it doesn't seem worth changing.)
699 *
700 * Note: since parsing and planning is done in fcontext, we will generate
701 * a lot of cruft that lives as long as the fcache does. This is annoying
702 * but we'll not worry about it until the module is rewritten to use
703 * plancache.c.
704 */
705 raw_parsetree_list = pg_parse_query(fcache->src);
706
707 queryTree_list = NIL;
708 flat_query_list = NIL;
709 foreach(lc, raw_parsetree_list)
710 {
711 RawStmt *parsetree = lfirst_node(RawStmt, lc);
712 List *queryTree_sublist;
713
714 queryTree_sublist = pg_analyze_and_rewrite_params(parsetree,
715 fcache->src,
716 (ParserSetupHook) sql_fn_parser_setup,
717 fcache->pinfo,
718 NULL);
719 queryTree_list = lappend(queryTree_list, queryTree_sublist);
720 flat_query_list = list_concat(flat_query_list,
721 list_copy(queryTree_sublist));
722 }
723
724 /*
725 * Check that the function returns the type it claims to. Although in
726 * simple cases this was already done when the function was defined, we
727 * have to recheck because database objects used in the function's queries
728 * might have changed type. We'd have to do it anyway if the function had
729 * any polymorphic arguments.
730 *
731 * Note: we set fcache->returnsTuple according to whether we are returning
732 * the whole tuple result or just a single column. In the latter case we
733 * clear returnsTuple because we need not act different from the scalar
734 * result case, even if it's a rowtype column. (However, we have to force
735 * lazy eval mode in that case; otherwise we'd need extra code to expand
736 * the rowtype column into multiple columns, since we have no way to
737 * notify the caller that it should do that.)
738 *
739 * check_sql_fn_retval will also construct a JunkFilter we can use to
740 * coerce the returned rowtype to the desired form (unless the result type
741 * is VOID, in which case there's nothing to coerce to).
742 */
743 fcache->returnsTuple = check_sql_fn_retval(foid,
744 rettype,
745 flat_query_list,
746 NULL,
747 &fcache->junkFilter);
748
749 if (fcache->returnsTuple)
750 {
751 /* Make sure output rowtype is properly blessed */
752 BlessTupleDesc(fcache->junkFilter->jf_resultSlot->tts_tupleDescriptor);
753 }
754 else if (fcache->returnsSet && type_is_rowtype(fcache->rettype))
755 {
756 /*
757 * Returning rowtype as if it were scalar --- materialize won't work.
758 * Right now it's sufficient to override any caller preference for
759 * materialize mode, but to add more smarts in init_execution_state
760 * about this, we'd probably need a three-way flag instead of bool.
761 */
762 lazyEvalOK = true;
763 }
764
765 /* Finally, plan the queries */
766 fcache->func_state = init_execution_state(queryTree_list,
767 fcache,
768 lazyEvalOK);
769
770 /* Mark fcache with time of creation to show it's valid */
771 fcache->lxid = MyProc->lxid;
772 fcache->subxid = GetCurrentSubTransactionId();
773
774 ReleaseSysCache(procedureTuple);
775
776 MemoryContextSwitchTo(oldcontext);
777 }
778
779 /* Start up execution of one execution_state node */
780 static void
postquel_start(execution_state * es,SQLFunctionCachePtr fcache)781 postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
782 {
783 DestReceiver *dest;
784
785 Assert(es->qd == NULL);
786
787 /* Caller should have ensured a suitable snapshot is active */
788 Assert(ActiveSnapshotSet());
789
790 /*
791 * If this query produces the function result, send its output to the
792 * tuplestore; else discard any output.
793 */
794 if (es->setsResult)
795 {
796 DR_sqlfunction *myState;
797
798 dest = CreateDestReceiver(DestSQLFunction);
799 /* pass down the needed info to the dest receiver routines */
800 myState = (DR_sqlfunction *) dest;
801 Assert(myState->pub.mydest == DestSQLFunction);
802 myState->tstore = fcache->tstore;
803 myState->cxt = CurrentMemoryContext;
804 myState->filter = fcache->junkFilter;
805 }
806 else
807 dest = None_Receiver;
808
809 es->qd = CreateQueryDesc(es->stmt,
810 fcache->src,
811 GetActiveSnapshot(),
812 InvalidSnapshot,
813 dest,
814 fcache->paramLI,
815 es->qd ? es->qd->queryEnv : NULL,
816 0);
817
818 /* Utility commands don't need Executor. */
819 if (es->qd->operation != CMD_UTILITY)
820 {
821 /*
822 * In lazyEval mode, do not let the executor set up an AfterTrigger
823 * context. This is necessary not just an optimization, because we
824 * mustn't exit from the function execution with a stacked
825 * AfterTrigger level still active. We are careful not to select
826 * lazyEval mode for any statement that could possibly queue triggers.
827 */
828 int eflags;
829
830 if (es->lazyEval)
831 eflags = EXEC_FLAG_SKIP_TRIGGERS;
832 else
833 eflags = 0; /* default run-to-completion flags */
834 ExecutorStart(es->qd, eflags);
835 }
836
837 es->status = F_EXEC_RUN;
838 }
839
840 /* Run one execution_state; either to completion or to first result row */
841 /* Returns true if we ran to completion */
842 static bool
postquel_getnext(execution_state * es,SQLFunctionCachePtr fcache)843 postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache)
844 {
845 bool result;
846
847 if (es->qd->operation == CMD_UTILITY)
848 {
849 ProcessUtility(es->qd->plannedstmt,
850 fcache->src,
851 PROCESS_UTILITY_QUERY,
852 es->qd->params,
853 es->qd->queryEnv,
854 es->qd->dest,
855 NULL);
856 result = true; /* never stops early */
857 }
858 else
859 {
860 /* Run regular commands to completion unless lazyEval */
861 uint64 count = (es->lazyEval) ? 1 : 0;
862
863 ExecutorRun(es->qd, ForwardScanDirection, count, !fcache->returnsSet || !es->lazyEval);
864
865 /*
866 * If we requested run to completion OR there was no tuple returned,
867 * command must be complete.
868 */
869 result = (count == 0 || es->qd->estate->es_processed == 0);
870 }
871
872 return result;
873 }
874
875 /* Shut down execution of one execution_state node */
876 static void
postquel_end(execution_state * es)877 postquel_end(execution_state *es)
878 {
879 /* mark status done to ensure we don't do ExecutorEnd twice */
880 es->status = F_EXEC_DONE;
881
882 /* Utility commands don't need Executor. */
883 if (es->qd->operation != CMD_UTILITY)
884 {
885 ExecutorFinish(es->qd);
886 ExecutorEnd(es->qd);
887 }
888
889 (*es->qd->dest->rDestroy) (es->qd->dest);
890
891 FreeQueryDesc(es->qd);
892 es->qd = NULL;
893 }
894
895 /* Build ParamListInfo array representing current arguments */
896 static void
postquel_sub_params(SQLFunctionCachePtr fcache,FunctionCallInfo fcinfo)897 postquel_sub_params(SQLFunctionCachePtr fcache,
898 FunctionCallInfo fcinfo)
899 {
900 int nargs = fcinfo->nargs;
901
902 if (nargs > 0)
903 {
904 ParamListInfo paramLI;
905 int i;
906
907 if (fcache->paramLI == NULL)
908 {
909 paramLI = (ParamListInfo)
910 palloc(offsetof(ParamListInfoData, params) +
911 nargs * sizeof(ParamExternData));
912 /* we have static list of params, so no hooks needed */
913 paramLI->paramFetch = NULL;
914 paramLI->paramFetchArg = NULL;
915 paramLI->parserSetup = NULL;
916 paramLI->parserSetupArg = NULL;
917 paramLI->numParams = nargs;
918 paramLI->paramMask = NULL;
919 fcache->paramLI = paramLI;
920 }
921 else
922 {
923 paramLI = fcache->paramLI;
924 Assert(paramLI->numParams == nargs);
925 }
926
927 for (i = 0; i < nargs; i++)
928 {
929 ParamExternData *prm = ¶mLI->params[i];
930
931 prm->value = fcinfo->arg[i];
932 prm->isnull = fcinfo->argnull[i];
933 prm->pflags = 0;
934 prm->ptype = fcache->pinfo->argtypes[i];
935 }
936 }
937 else
938 fcache->paramLI = NULL;
939 }
940
941 /*
942 * Extract the SQL function's value from a single result row. This is used
943 * both for scalar (non-set) functions and for each row of a lazy-eval set
944 * result.
945 */
946 static Datum
postquel_get_single_result(TupleTableSlot * slot,FunctionCallInfo fcinfo,SQLFunctionCachePtr fcache,MemoryContext resultcontext)947 postquel_get_single_result(TupleTableSlot *slot,
948 FunctionCallInfo fcinfo,
949 SQLFunctionCachePtr fcache,
950 MemoryContext resultcontext)
951 {
952 Datum value;
953 MemoryContext oldcontext;
954
955 /*
956 * Set up to return the function value. For pass-by-reference datatypes,
957 * be sure to allocate the result in resultcontext, not the current memory
958 * context (which has query lifespan). We can't leave the data in the
959 * TupleTableSlot because we intend to clear the slot before returning.
960 */
961 oldcontext = MemoryContextSwitchTo(resultcontext);
962
963 if (fcache->returnsTuple)
964 {
965 /* We must return the whole tuple as a Datum. */
966 fcinfo->isnull = false;
967 value = ExecFetchSlotTupleDatum(slot);
968 }
969 else
970 {
971 /*
972 * Returning a scalar, which we have to extract from the first column
973 * of the SELECT result, and then copy into result context if needed.
974 */
975 value = slot_getattr(slot, 1, &(fcinfo->isnull));
976
977 if (!fcinfo->isnull)
978 value = datumCopy(value, fcache->typbyval, fcache->typlen);
979 }
980
981 MemoryContextSwitchTo(oldcontext);
982
983 return value;
984 }
985
986 /*
987 * fmgr_sql: function call manager for SQL functions
988 */
989 Datum
fmgr_sql(PG_FUNCTION_ARGS)990 fmgr_sql(PG_FUNCTION_ARGS)
991 {
992 SQLFunctionCachePtr fcache;
993 ErrorContextCallback sqlerrcontext;
994 MemoryContext oldcontext;
995 bool randomAccess;
996 bool lazyEvalOK;
997 bool is_first;
998 bool pushed_snapshot;
999 execution_state *es;
1000 TupleTableSlot *slot;
1001 Datum result;
1002 List *eslist;
1003 ListCell *eslc;
1004
1005 /*
1006 * Setup error traceback support for ereport()
1007 */
1008 sqlerrcontext.callback = sql_exec_error_callback;
1009 sqlerrcontext.arg = fcinfo->flinfo;
1010 sqlerrcontext.previous = error_context_stack;
1011 error_context_stack = &sqlerrcontext;
1012
1013 /* Check call context */
1014 if (fcinfo->flinfo->fn_retset)
1015 {
1016 ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
1017
1018 /*
1019 * For simplicity, we require callers to support both set eval modes.
1020 * There are cases where we must use one or must use the other, and
1021 * it's not really worthwhile to postpone the check till we know. But
1022 * note we do not require caller to provide an expectedDesc.
1023 */
1024 if (!rsi || !IsA(rsi, ReturnSetInfo) ||
1025 (rsi->allowedModes & SFRM_ValuePerCall) == 0 ||
1026 (rsi->allowedModes & SFRM_Materialize) == 0)
1027 ereport(ERROR,
1028 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1029 errmsg("set-valued function called in context that cannot accept a set")));
1030 randomAccess = rsi->allowedModes & SFRM_Materialize_Random;
1031 lazyEvalOK = !(rsi->allowedModes & SFRM_Materialize_Preferred);
1032 }
1033 else
1034 {
1035 randomAccess = false;
1036 lazyEvalOK = true;
1037 }
1038
1039 /*
1040 * Initialize fcache (build plans) if first time through; or re-initialize
1041 * if the cache is stale.
1042 */
1043 fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
1044
1045 if (fcache != NULL)
1046 {
1047 if (fcache->lxid != MyProc->lxid ||
1048 !SubTransactionIsActive(fcache->subxid))
1049 {
1050 /* It's stale; unlink and delete */
1051 fcinfo->flinfo->fn_extra = NULL;
1052 MemoryContextDelete(fcache->fcontext);
1053 fcache = NULL;
1054 }
1055 }
1056
1057 if (fcache == NULL)
1058 {
1059 init_sql_fcache(fcinfo->flinfo, PG_GET_COLLATION(), lazyEvalOK);
1060 fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
1061 }
1062
1063 /*
1064 * Switch to context in which the fcache lives. This ensures that our
1065 * tuplestore etc will have sufficient lifetime. The sub-executor is
1066 * responsible for deleting per-tuple information. (XXX in the case of a
1067 * long-lived FmgrInfo, this policy represents more memory leakage, but
1068 * it's not entirely clear where to keep stuff instead.)
1069 */
1070 oldcontext = MemoryContextSwitchTo(fcache->fcontext);
1071
1072 /*
1073 * Find first unfinished query in function, and note whether it's the
1074 * first query.
1075 */
1076 eslist = fcache->func_state;
1077 es = NULL;
1078 is_first = true;
1079 foreach(eslc, eslist)
1080 {
1081 es = (execution_state *) lfirst(eslc);
1082
1083 while (es && es->status == F_EXEC_DONE)
1084 {
1085 is_first = false;
1086 es = es->next;
1087 }
1088
1089 if (es)
1090 break;
1091 }
1092
1093 /*
1094 * Convert params to appropriate format if starting a fresh execution. (If
1095 * continuing execution, we can re-use prior params.)
1096 */
1097 if (is_first && es && es->status == F_EXEC_START)
1098 postquel_sub_params(fcache, fcinfo);
1099
1100 /*
1101 * Build tuplestore to hold results, if we don't have one already. Note
1102 * it's in the query-lifespan context.
1103 */
1104 if (!fcache->tstore)
1105 fcache->tstore = tuplestore_begin_heap(randomAccess, false, work_mem);
1106
1107 /*
1108 * Execute each command in the function one after another until we either
1109 * run out of commands or get a result row from a lazily-evaluated SELECT.
1110 *
1111 * Notes about snapshot management:
1112 *
1113 * In a read-only function, we just use the surrounding query's snapshot.
1114 *
1115 * In a non-read-only function, we rely on the fact that we'll never
1116 * suspend execution between queries of the function: the only reason to
1117 * suspend execution before completion is if we are returning a row from a
1118 * lazily-evaluated SELECT. So, when first entering this loop, we'll
1119 * either start a new query (and push a fresh snapshot) or re-establish
1120 * the active snapshot from the existing query descriptor. If we need to
1121 * start a new query in a subsequent execution of the loop, either we need
1122 * a fresh snapshot (and pushed_snapshot is false) or the existing
1123 * snapshot is on the active stack and we can just bump its command ID.
1124 */
1125 pushed_snapshot = false;
1126 while (es)
1127 {
1128 bool completed;
1129
1130 if (es->status == F_EXEC_START)
1131 {
1132 /*
1133 * If not read-only, be sure to advance the command counter for
1134 * each command, so that all work to date in this transaction is
1135 * visible. Take a new snapshot if we don't have one yet,
1136 * otherwise just bump the command ID in the existing snapshot.
1137 */
1138 if (!fcache->readonly_func)
1139 {
1140 CommandCounterIncrement();
1141 if (!pushed_snapshot)
1142 {
1143 PushActiveSnapshot(GetTransactionSnapshot());
1144 pushed_snapshot = true;
1145 }
1146 else
1147 UpdateActiveSnapshotCommandId();
1148 }
1149
1150 postquel_start(es, fcache);
1151 }
1152 else if (!fcache->readonly_func && !pushed_snapshot)
1153 {
1154 /* Re-establish active snapshot when re-entering function */
1155 PushActiveSnapshot(es->qd->snapshot);
1156 pushed_snapshot = true;
1157 }
1158
1159 completed = postquel_getnext(es, fcache);
1160
1161 /*
1162 * If we ran the command to completion, we can shut it down now. Any
1163 * row(s) we need to return are safely stashed in the tuplestore, and
1164 * we want to be sure that, for example, AFTER triggers get fired
1165 * before we return anything. Also, if the function doesn't return
1166 * set, we can shut it down anyway because it must be a SELECT and we
1167 * don't care about fetching any more result rows.
1168 */
1169 if (completed || !fcache->returnsSet)
1170 postquel_end(es);
1171
1172 /*
1173 * Break from loop if we didn't shut down (implying we got a
1174 * lazily-evaluated row). Otherwise we'll press on till the whole
1175 * function is done, relying on the tuplestore to keep hold of the
1176 * data to eventually be returned. This is necessary since an
1177 * INSERT/UPDATE/DELETE RETURNING that sets the result might be
1178 * followed by additional rule-inserted commands, and we want to
1179 * finish doing all those commands before we return anything.
1180 */
1181 if (es->status != F_EXEC_DONE)
1182 break;
1183
1184 /*
1185 * Advance to next execution_state, which might be in the next list.
1186 */
1187 es = es->next;
1188 while (!es)
1189 {
1190 eslc = lnext(eslc);
1191 if (!eslc)
1192 break; /* end of function */
1193
1194 es = (execution_state *) lfirst(eslc);
1195
1196 /*
1197 * Flush the current snapshot so that we will take a new one for
1198 * the new query list. This ensures that new snaps are taken at
1199 * original-query boundaries, matching the behavior of interactive
1200 * execution.
1201 */
1202 if (pushed_snapshot)
1203 {
1204 PopActiveSnapshot();
1205 pushed_snapshot = false;
1206 }
1207 }
1208 }
1209
1210 /*
1211 * The tuplestore now contains whatever row(s) we are supposed to return.
1212 */
1213 if (fcache->returnsSet)
1214 {
1215 ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
1216
1217 if (es)
1218 {
1219 /*
1220 * If we stopped short of being done, we must have a lazy-eval
1221 * row.
1222 */
1223 Assert(es->lazyEval);
1224 /* Re-use the junkfilter's output slot to fetch back the tuple */
1225 Assert(fcache->junkFilter);
1226 slot = fcache->junkFilter->jf_resultSlot;
1227 if (!tuplestore_gettupleslot(fcache->tstore, true, false, slot))
1228 elog(ERROR, "failed to fetch lazy-eval tuple");
1229 /* Extract the result as a datum, and copy out from the slot */
1230 result = postquel_get_single_result(slot, fcinfo,
1231 fcache, oldcontext);
1232 /* Clear the tuplestore, but keep it for next time */
1233 /* NB: this might delete the slot's content, but we don't care */
1234 tuplestore_clear(fcache->tstore);
1235
1236 /*
1237 * Let caller know we're not finished.
1238 */
1239 rsi->isDone = ExprMultipleResult;
1240
1241 /*
1242 * Ensure we will get shut down cleanly if the exprcontext is not
1243 * run to completion.
1244 */
1245 if (!fcache->shutdown_reg)
1246 {
1247 RegisterExprContextCallback(rsi->econtext,
1248 ShutdownSQLFunction,
1249 PointerGetDatum(fcache));
1250 fcache->shutdown_reg = true;
1251 }
1252 }
1253 else if (fcache->lazyEval)
1254 {
1255 /*
1256 * We are done with a lazy evaluation. Clean up.
1257 */
1258 tuplestore_clear(fcache->tstore);
1259
1260 /*
1261 * Let caller know we're finished.
1262 */
1263 rsi->isDone = ExprEndResult;
1264
1265 fcinfo->isnull = true;
1266 result = (Datum) 0;
1267
1268 /* Deregister shutdown callback, if we made one */
1269 if (fcache->shutdown_reg)
1270 {
1271 UnregisterExprContextCallback(rsi->econtext,
1272 ShutdownSQLFunction,
1273 PointerGetDatum(fcache));
1274 fcache->shutdown_reg = false;
1275 }
1276 }
1277 else
1278 {
1279 /*
1280 * We are done with a non-lazy evaluation. Return whatever is in
1281 * the tuplestore. (It is now caller's responsibility to free the
1282 * tuplestore when done.)
1283 */
1284 rsi->returnMode = SFRM_Materialize;
1285 rsi->setResult = fcache->tstore;
1286 fcache->tstore = NULL;
1287 /* must copy desc because execSRF.c will free it */
1288 if (fcache->junkFilter)
1289 rsi->setDesc = CreateTupleDescCopy(fcache->junkFilter->jf_cleanTupType);
1290
1291 fcinfo->isnull = true;
1292 result = (Datum) 0;
1293
1294 /* Deregister shutdown callback, if we made one */
1295 if (fcache->shutdown_reg)
1296 {
1297 UnregisterExprContextCallback(rsi->econtext,
1298 ShutdownSQLFunction,
1299 PointerGetDatum(fcache));
1300 fcache->shutdown_reg = false;
1301 }
1302 }
1303 }
1304 else
1305 {
1306 /*
1307 * Non-set function. If we got a row, return it; else return NULL.
1308 */
1309 if (fcache->junkFilter)
1310 {
1311 /* Re-use the junkfilter's output slot to fetch back the tuple */
1312 slot = fcache->junkFilter->jf_resultSlot;
1313 if (tuplestore_gettupleslot(fcache->tstore, true, false, slot))
1314 result = postquel_get_single_result(slot, fcinfo,
1315 fcache, oldcontext);
1316 else
1317 {
1318 fcinfo->isnull = true;
1319 result = (Datum) 0;
1320 }
1321 }
1322 else
1323 {
1324 /* Should only get here for VOID functions */
1325 Assert(fcache->rettype == VOIDOID);
1326 fcinfo->isnull = true;
1327 result = (Datum) 0;
1328 }
1329
1330 /* Clear the tuplestore, but keep it for next time */
1331 tuplestore_clear(fcache->tstore);
1332 }
1333
1334 /* Pop snapshot if we have pushed one */
1335 if (pushed_snapshot)
1336 PopActiveSnapshot();
1337
1338 /*
1339 * If we've gone through every command in the function, we are done. Reset
1340 * the execution states to start over again on next call.
1341 */
1342 if (es == NULL)
1343 {
1344 foreach(eslc, fcache->func_state)
1345 {
1346 es = (execution_state *) lfirst(eslc);
1347 while (es)
1348 {
1349 es->status = F_EXEC_START;
1350 es = es->next;
1351 }
1352 }
1353 }
1354
1355 error_context_stack = sqlerrcontext.previous;
1356
1357 MemoryContextSwitchTo(oldcontext);
1358
1359 return result;
1360 }
1361
1362
1363 /*
1364 * error context callback to let us supply a call-stack traceback
1365 */
1366 static void
sql_exec_error_callback(void * arg)1367 sql_exec_error_callback(void *arg)
1368 {
1369 FmgrInfo *flinfo = (FmgrInfo *) arg;
1370 SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) flinfo->fn_extra;
1371 int syntaxerrposition;
1372
1373 /*
1374 * We can do nothing useful if init_sql_fcache() didn't get as far as
1375 * saving the function name
1376 */
1377 if (fcache == NULL || fcache->fname == NULL)
1378 return;
1379
1380 /*
1381 * If there is a syntax error position, convert to internal syntax error
1382 */
1383 syntaxerrposition = geterrposition();
1384 if (syntaxerrposition > 0 && fcache->src != NULL)
1385 {
1386 errposition(0);
1387 internalerrposition(syntaxerrposition);
1388 internalerrquery(fcache->src);
1389 }
1390
1391 /*
1392 * Try to determine where in the function we failed. If there is a query
1393 * with non-null QueryDesc, finger it. (We check this rather than looking
1394 * for F_EXEC_RUN state, so that errors during ExecutorStart or
1395 * ExecutorEnd are blamed on the appropriate query; see postquel_start and
1396 * postquel_end.)
1397 */
1398 if (fcache->func_state)
1399 {
1400 execution_state *es;
1401 int query_num;
1402 ListCell *lc;
1403
1404 es = NULL;
1405 query_num = 1;
1406 foreach(lc, fcache->func_state)
1407 {
1408 es = (execution_state *) lfirst(lc);
1409 while (es)
1410 {
1411 if (es->qd)
1412 {
1413 errcontext("SQL function \"%s\" statement %d",
1414 fcache->fname, query_num);
1415 break;
1416 }
1417 es = es->next;
1418 }
1419 if (es)
1420 break;
1421 query_num++;
1422 }
1423 if (es == NULL)
1424 {
1425 /*
1426 * couldn't identify a running query; might be function entry,
1427 * function exit, or between queries.
1428 */
1429 errcontext("SQL function \"%s\"", fcache->fname);
1430 }
1431 }
1432 else
1433 {
1434 /*
1435 * Assume we failed during init_sql_fcache(). (It's possible that the
1436 * function actually has an empty body, but in that case we may as
1437 * well report all errors as being "during startup".)
1438 */
1439 errcontext("SQL function \"%s\" during startup", fcache->fname);
1440 }
1441 }
1442
1443
1444 /*
1445 * callback function in case a function-returning-set needs to be shut down
1446 * before it has been run to completion
1447 */
1448 static void
ShutdownSQLFunction(Datum arg)1449 ShutdownSQLFunction(Datum arg)
1450 {
1451 SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
1452 execution_state *es;
1453 ListCell *lc;
1454
1455 foreach(lc, fcache->func_state)
1456 {
1457 es = (execution_state *) lfirst(lc);
1458 while (es)
1459 {
1460 /* Shut down anything still running */
1461 if (es->status == F_EXEC_RUN)
1462 {
1463 /* Re-establish active snapshot for any called functions */
1464 if (!fcache->readonly_func)
1465 PushActiveSnapshot(es->qd->snapshot);
1466
1467 postquel_end(es);
1468
1469 if (!fcache->readonly_func)
1470 PopActiveSnapshot();
1471 }
1472
1473 /* Reset states to START in case we're called again */
1474 es->status = F_EXEC_START;
1475 es = es->next;
1476 }
1477 }
1478
1479 /* Release tuplestore if we have one */
1480 if (fcache->tstore)
1481 tuplestore_end(fcache->tstore);
1482 fcache->tstore = NULL;
1483
1484 /* execUtils will deregister the callback... */
1485 fcache->shutdown_reg = false;
1486 }
1487
1488
1489 /*
1490 * check_sql_fn_retval() -- check return value of a list of sql parse trees.
1491 *
1492 * The return value of a sql function is the value returned by the last
1493 * canSetTag query in the function. We do some ad-hoc type checking here
1494 * to be sure that the user is returning the type he claims. There are
1495 * also a couple of strange-looking features to assist callers in dealing
1496 * with allowed special cases, such as binary-compatible result types.
1497 *
1498 * For a polymorphic function the passed rettype must be the actual resolved
1499 * output type of the function; we should never see a polymorphic pseudotype
1500 * such as ANYELEMENT as rettype. (This means we can't check the type during
1501 * function definition of a polymorphic function.)
1502 *
1503 * This function returns true if the sql function returns the entire tuple
1504 * result of its final statement, or false if it returns just the first column
1505 * result of that statement. It throws an error if the final statement doesn't
1506 * return the right type at all.
1507 *
1508 * Note that because we allow "SELECT rowtype_expression", the result can be
1509 * false even when the declared function return type is a rowtype.
1510 *
1511 * If modifyTargetList isn't NULL, the function will modify the final
1512 * statement's targetlist in two cases:
1513 * (1) if the tlist returns values that are binary-coercible to the expected
1514 * type rather than being exactly the expected type. RelabelType nodes will
1515 * be inserted to make the result types match exactly.
1516 * (2) if there are dropped columns in the declared result rowtype. NULL
1517 * output columns will be inserted in the tlist to match them.
1518 * (Obviously the caller must pass a parsetree that is okay to modify when
1519 * using this flag.) Note that this flag does not affect whether the tlist is
1520 * considered to be a legal match to the result type, only how we react to
1521 * allowed not-exact-match cases. *modifyTargetList will be set true iff
1522 * we had to make any "dangerous" changes that could modify the semantics of
1523 * the statement. If it is set true, the caller should not use the modified
1524 * statement, but for simplicity we apply the changes anyway.
1525 *
1526 * If junkFilter isn't NULL, then *junkFilter is set to a JunkFilter defined
1527 * to convert the function's tuple result to the correct output tuple type.
1528 * Exception: if the function is defined to return VOID then *junkFilter is
1529 * set to NULL.
1530 */
1531 bool
check_sql_fn_retval(Oid func_id,Oid rettype,List * queryTreeList,bool * modifyTargetList,JunkFilter ** junkFilter)1532 check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
1533 bool *modifyTargetList,
1534 JunkFilter **junkFilter)
1535 {
1536 Query *parse;
1537 List **tlist_ptr;
1538 List *tlist;
1539 int tlistlen;
1540 char fn_typtype;
1541 Oid restype;
1542 ListCell *lc;
1543
1544 AssertArg(!IsPolymorphicType(rettype));
1545
1546 if (modifyTargetList)
1547 *modifyTargetList = false; /* initialize for no change */
1548 if (junkFilter)
1549 *junkFilter = NULL; /* initialize in case of VOID result */
1550
1551 /*
1552 * Find the last canSetTag query in the list. This isn't necessarily the
1553 * last parsetree, because rule rewriting can insert queries after what
1554 * the user wrote.
1555 */
1556 parse = NULL;
1557 foreach(lc, queryTreeList)
1558 {
1559 Query *q = lfirst_node(Query, lc);
1560
1561 if (q->canSetTag)
1562 parse = q;
1563 }
1564
1565 /*
1566 * If it's a plain SELECT, it returns whatever the targetlist says.
1567 * Otherwise, if it's INSERT/UPDATE/DELETE with RETURNING, it returns
1568 * that. Otherwise, the function return type must be VOID.
1569 *
1570 * Note: eventually replace this test with QueryReturnsTuples? We'd need
1571 * a more general method of determining the output type, though. Also, it
1572 * seems too dangerous to consider FETCH or EXECUTE as returning a
1573 * determinable rowtype, since they depend on relatively short-lived
1574 * entities.
1575 */
1576 if (parse &&
1577 parse->commandType == CMD_SELECT)
1578 {
1579 tlist_ptr = &parse->targetList;
1580 tlist = parse->targetList;
1581 }
1582 else if (parse &&
1583 (parse->commandType == CMD_INSERT ||
1584 parse->commandType == CMD_UPDATE ||
1585 parse->commandType == CMD_DELETE) &&
1586 parse->returningList)
1587 {
1588 tlist_ptr = &parse->returningList;
1589 tlist = parse->returningList;
1590 }
1591 else
1592 {
1593 /* Empty function body, or last statement is a utility command */
1594 if (rettype != VOIDOID)
1595 ereport(ERROR,
1596 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1597 errmsg("return type mismatch in function declared to return %s",
1598 format_type_be(rettype)),
1599 errdetail("Function's final statement must be SELECT or INSERT/UPDATE/DELETE RETURNING.")));
1600 return false;
1601 }
1602
1603 /*
1604 * OK, check that the targetlist returns something matching the declared
1605 * type. (We used to insist that the declared type not be VOID in this
1606 * case, but that makes it hard to write a void function that exits after
1607 * calling another void function. Instead, we insist that the tlist
1608 * return void ... so void is treated as if it were a scalar type below.)
1609 */
1610
1611 /*
1612 * Count the non-junk entries in the result targetlist.
1613 */
1614 tlistlen = ExecCleanTargetListLength(tlist);
1615
1616 fn_typtype = get_typtype(rettype);
1617
1618 if (fn_typtype == TYPTYPE_BASE ||
1619 fn_typtype == TYPTYPE_DOMAIN ||
1620 fn_typtype == TYPTYPE_ENUM ||
1621 fn_typtype == TYPTYPE_RANGE ||
1622 rettype == VOIDOID)
1623 {
1624 /*
1625 * For scalar-type returns, the target list must have exactly one
1626 * non-junk entry, and its type must agree with what the user
1627 * declared; except we allow binary-compatible types too.
1628 */
1629 TargetEntry *tle;
1630
1631 if (tlistlen != 1)
1632 ereport(ERROR,
1633 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1634 errmsg("return type mismatch in function declared to return %s",
1635 format_type_be(rettype)),
1636 errdetail("Final statement must return exactly one column.")));
1637
1638 /* We assume here that non-junk TLEs must come first in tlists */
1639 tle = (TargetEntry *) linitial(tlist);
1640 Assert(!tle->resjunk);
1641
1642 restype = exprType((Node *) tle->expr);
1643 if (!IsBinaryCoercible(restype, rettype))
1644 ereport(ERROR,
1645 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1646 errmsg("return type mismatch in function declared to return %s",
1647 format_type_be(rettype)),
1648 errdetail("Actual return type is %s.",
1649 format_type_be(restype))));
1650 if (modifyTargetList && restype != rettype)
1651 {
1652 tle->expr = (Expr *) makeRelabelType(tle->expr,
1653 rettype,
1654 -1,
1655 get_typcollation(rettype),
1656 COERCE_IMPLICIT_CAST);
1657 /* Relabel is dangerous if TLE is a sort/group or setop column */
1658 if (tle->ressortgroupref != 0 || parse->setOperations)
1659 *modifyTargetList = true;
1660 }
1661
1662 /* Set up junk filter if needed */
1663 if (junkFilter)
1664 *junkFilter = ExecInitJunkFilter(tlist, false, NULL);
1665 }
1666 else if (fn_typtype == TYPTYPE_COMPOSITE || rettype == RECORDOID)
1667 {
1668 /* Returns a rowtype */
1669 TupleDesc tupdesc;
1670 int tupnatts; /* physical number of columns in tuple */
1671 int tuplogcols; /* # of nondeleted columns in tuple */
1672 int colindex; /* physical column index */
1673 List *newtlist; /* new non-junk tlist entries */
1674 List *junkattrs; /* new junk tlist entries */
1675
1676 /*
1677 * If the target list is of length 1, and the type of the varnode in
1678 * the target list matches the declared return type, this is okay.
1679 * This can happen, for example, where the body of the function is
1680 * 'SELECT func2()', where func2 has the same composite return type as
1681 * the function that's calling it.
1682 *
1683 * XXX Note that if rettype is RECORD, the IsBinaryCoercible check
1684 * will succeed for any composite restype. For the moment we rely on
1685 * runtime type checking to catch any discrepancy, but it'd be nice to
1686 * do better at parse time.
1687 */
1688 if (tlistlen == 1)
1689 {
1690 TargetEntry *tle = (TargetEntry *) linitial(tlist);
1691
1692 Assert(!tle->resjunk);
1693 restype = exprType((Node *) tle->expr);
1694 if (IsBinaryCoercible(restype, rettype))
1695 {
1696 if (modifyTargetList && restype != rettype)
1697 {
1698 tle->expr = (Expr *) makeRelabelType(tle->expr,
1699 rettype,
1700 -1,
1701 get_typcollation(rettype),
1702 COERCE_IMPLICIT_CAST);
1703 /* Relabel is dangerous if sort/group or setop column */
1704 if (tle->ressortgroupref != 0 || parse->setOperations)
1705 *modifyTargetList = true;
1706 }
1707 /* Set up junk filter if needed */
1708 if (junkFilter)
1709 *junkFilter = ExecInitJunkFilter(tlist, false, NULL);
1710 return false; /* NOT returning whole tuple */
1711 }
1712 }
1713
1714 /* Is the rowtype fixed, or determined only at runtime? */
1715 if (get_func_result_type(func_id, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
1716 {
1717 /*
1718 * Assume we are returning the whole tuple. Crosschecking against
1719 * what the caller expects will happen at runtime.
1720 */
1721 if (junkFilter)
1722 *junkFilter = ExecInitJunkFilter(tlist, false, NULL);
1723 return true;
1724 }
1725 Assert(tupdesc);
1726
1727 /*
1728 * Verify that the targetlist matches the return tuple type. We scan
1729 * the non-deleted attributes to ensure that they match the datatypes
1730 * of the non-resjunk columns. For deleted attributes, insert NULL
1731 * result columns if the caller asked for that.
1732 */
1733 tupnatts = tupdesc->natts;
1734 tuplogcols = 0; /* we'll count nondeleted cols as we go */
1735 colindex = 0;
1736 newtlist = NIL; /* these are only used if modifyTargetList */
1737 junkattrs = NIL;
1738
1739 foreach(lc, tlist)
1740 {
1741 TargetEntry *tle = (TargetEntry *) lfirst(lc);
1742 Form_pg_attribute attr;
1743 Oid tletype;
1744 Oid atttype;
1745
1746 if (tle->resjunk)
1747 {
1748 if (modifyTargetList)
1749 junkattrs = lappend(junkattrs, tle);
1750 continue;
1751 }
1752
1753 do
1754 {
1755 colindex++;
1756 if (colindex > tupnatts)
1757 ereport(ERROR,
1758 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1759 errmsg("return type mismatch in function declared to return %s",
1760 format_type_be(rettype)),
1761 errdetail("Final statement returns too many columns.")));
1762 attr = tupdesc->attrs[colindex - 1];
1763 if (attr->attisdropped && modifyTargetList)
1764 {
1765 Expr *null_expr;
1766
1767 /* The type of the null we insert isn't important */
1768 null_expr = (Expr *) makeConst(INT4OID,
1769 -1,
1770 InvalidOid,
1771 sizeof(int32),
1772 (Datum) 0,
1773 true, /* isnull */
1774 true /* byval */ );
1775 newtlist = lappend(newtlist,
1776 makeTargetEntry(null_expr,
1777 colindex,
1778 NULL,
1779 false));
1780 /* NULL insertion is dangerous in a setop */
1781 if (parse->setOperations)
1782 *modifyTargetList = true;
1783 }
1784 } while (attr->attisdropped);
1785 tuplogcols++;
1786
1787 tletype = exprType((Node *) tle->expr);
1788 atttype = attr->atttypid;
1789 if (!IsBinaryCoercible(tletype, atttype))
1790 ereport(ERROR,
1791 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1792 errmsg("return type mismatch in function declared to return %s",
1793 format_type_be(rettype)),
1794 errdetail("Final statement returns %s instead of %s at column %d.",
1795 format_type_be(tletype),
1796 format_type_be(atttype),
1797 tuplogcols)));
1798 if (modifyTargetList)
1799 {
1800 if (tletype != atttype)
1801 {
1802 tle->expr = (Expr *) makeRelabelType(tle->expr,
1803 atttype,
1804 -1,
1805 get_typcollation(atttype),
1806 COERCE_IMPLICIT_CAST);
1807 /* Relabel is dangerous if sort/group or setop column */
1808 if (tle->ressortgroupref != 0 || parse->setOperations)
1809 *modifyTargetList = true;
1810 }
1811 tle->resno = colindex;
1812 newtlist = lappend(newtlist, tle);
1813 }
1814 }
1815
1816 /* remaining columns in tupdesc had better all be dropped */
1817 for (colindex++; colindex <= tupnatts; colindex++)
1818 {
1819 if (!tupdesc->attrs[colindex - 1]->attisdropped)
1820 ereport(ERROR,
1821 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1822 errmsg("return type mismatch in function declared to return %s",
1823 format_type_be(rettype)),
1824 errdetail("Final statement returns too few columns.")));
1825 if (modifyTargetList)
1826 {
1827 Expr *null_expr;
1828
1829 /* The type of the null we insert isn't important */
1830 null_expr = (Expr *) makeConst(INT4OID,
1831 -1,
1832 InvalidOid,
1833 sizeof(int32),
1834 (Datum) 0,
1835 true, /* isnull */
1836 true /* byval */ );
1837 newtlist = lappend(newtlist,
1838 makeTargetEntry(null_expr,
1839 colindex,
1840 NULL,
1841 false));
1842 /* NULL insertion is dangerous in a setop */
1843 if (parse->setOperations)
1844 *modifyTargetList = true;
1845 }
1846 }
1847
1848 if (modifyTargetList)
1849 {
1850 /* ensure resjunk columns are numbered correctly */
1851 foreach(lc, junkattrs)
1852 {
1853 TargetEntry *tle = (TargetEntry *) lfirst(lc);
1854
1855 tle->resno = colindex++;
1856 }
1857 /* replace the tlist with the modified one */
1858 *tlist_ptr = list_concat(newtlist, junkattrs);
1859 }
1860
1861 /* Set up junk filter if needed */
1862 if (junkFilter)
1863 *junkFilter = ExecInitJunkFilterConversion(tlist,
1864 CreateTupleDescCopy(tupdesc),
1865 NULL);
1866
1867 /* Report that we are returning entire tuple result */
1868 return true;
1869 }
1870 else
1871 ereport(ERROR,
1872 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1873 errmsg("return type %s is not supported for SQL functions",
1874 format_type_be(rettype))));
1875
1876 return false;
1877 }
1878
1879
1880 /*
1881 * CreateSQLFunctionDestReceiver -- create a suitable DestReceiver object
1882 */
1883 DestReceiver *
CreateSQLFunctionDestReceiver(void)1884 CreateSQLFunctionDestReceiver(void)
1885 {
1886 DR_sqlfunction *self = (DR_sqlfunction *) palloc0(sizeof(DR_sqlfunction));
1887
1888 self->pub.receiveSlot = sqlfunction_receive;
1889 self->pub.rStartup = sqlfunction_startup;
1890 self->pub.rShutdown = sqlfunction_shutdown;
1891 self->pub.rDestroy = sqlfunction_destroy;
1892 self->pub.mydest = DestSQLFunction;
1893
1894 /* private fields will be set by postquel_start */
1895
1896 return (DestReceiver *) self;
1897 }
1898
1899 /*
1900 * sqlfunction_startup --- executor startup
1901 */
1902 static void
sqlfunction_startup(DestReceiver * self,int operation,TupleDesc typeinfo)1903 sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
1904 {
1905 /* no-op */
1906 }
1907
1908 /*
1909 * sqlfunction_receive --- receive one tuple
1910 */
1911 static bool
sqlfunction_receive(TupleTableSlot * slot,DestReceiver * self)1912 sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self)
1913 {
1914 DR_sqlfunction *myState = (DR_sqlfunction *) self;
1915
1916 /* Filter tuple as needed */
1917 slot = ExecFilterJunk(myState->filter, slot);
1918
1919 /* Store the filtered tuple into the tuplestore */
1920 tuplestore_puttupleslot(myState->tstore, slot);
1921
1922 return true;
1923 }
1924
1925 /*
1926 * sqlfunction_shutdown --- executor end
1927 */
1928 static void
sqlfunction_shutdown(DestReceiver * self)1929 sqlfunction_shutdown(DestReceiver *self)
1930 {
1931 /* no-op */
1932 }
1933
1934 /*
1935 * sqlfunction_destroy --- release DestReceiver object
1936 */
1937 static void
sqlfunction_destroy(DestReceiver * self)1938 sqlfunction_destroy(DestReceiver *self)
1939 {
1940 pfree(self);
1941 }
1942