1/*-------------------------------------------------------------------------
2 *
3 * functions.c
4 * Execution of SQL-language functions
5 *
6 * Portions Copyright (c) 1996-2019, 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 */
41typedef 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 */
58typedef enum
59{
60 F_EXEC_START, F_EXEC_RUN, F_EXEC_DONE
61} ExecStatus;
62
63typedef 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 */
91typedef 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
128typedef 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 */
135typedef 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 */
147static Node *sql_fn_param_ref(ParseState *pstate, ParamRef *pref);
148static Node *sql_fn_post_column_ref(ParseState *pstate,
149 ColumnRef *cref, Node *var);
150static Node *sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,
151 int paramno, int location);
152static Node *sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,
153 const char *paramname, int location);
154static List *init_execution_state(List *queryTree_list,
155 SQLFunctionCachePtr fcache,
156 bool lazyEvalOK);
157static void init_sql_fcache(FmgrInfo *finfo, Oid collation, bool lazyEvalOK);
158static void postquel_start(execution_state *es, SQLFunctionCachePtr fcache);
159static bool postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache);
160static void postquel_end(execution_state *es);
161static void postquel_sub_params(SQLFunctionCachePtr fcache,
162 FunctionCallInfo fcinfo);
163static Datum postquel_get_single_result(TupleTableSlot *slot,
164 FunctionCallInfo fcinfo,
165 SQLFunctionCachePtr fcache,
166 MemoryContext resultcontext);
167static void sql_exec_error_callback(void *arg);
168static void ShutdownSQLFunction(Datum arg);
169static void sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
170static bool sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self);
171static void sqlfunction_shutdown(DestReceiver *self);
172static 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 */
183SQLFunctionParseInfoPtr
184prepare_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 */
272void
273sql_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 */
285static Node *
286sql_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 false,
394 cref->location);
395 }
396
397 return param;
398}
399
400/*
401 * sql_fn_param_ref parser callback for ParamRefs ($n symbols)
402 */
403static Node *
404sql_fn_param_ref(ParseState *pstate, ParamRef *pref)
405{
406 SQLFunctionParseInfoPtr pinfo = (SQLFunctionParseInfoPtr) pstate->p_ref_hook_state;
407 int paramno = pref->number;
408
409 /* Check parameter number is valid */
410 if (paramno <= 0 || paramno > pinfo->nargs)
411 return NULL; /* unknown parameter number */
412
413 return sql_fn_make_param(pinfo, paramno, pref->location);
414}
415
416/*
417 * sql_fn_make_param construct a Param node for the given paramno
418 */
419static Node *
420sql_fn_make_param(SQLFunctionParseInfoPtr pinfo,
421 int paramno, int location)
422{
423 Param *param;
424
425 param = makeNode(Param);
426 param->paramkind = PARAM_EXTERN;
427 param->paramid = paramno;
428 param->paramtype = pinfo->argtypes[paramno - 1];
429 param->paramtypmod = -1;
430 param->paramcollid = get_typcollation(param->paramtype);
431 param->location = location;
432
433 /*
434 * If we have a function input collation, allow it to override the
435 * type-derived collation for parameter symbols. (XXX perhaps this should
436 * not happen if the type collation is not default?)
437 */
438 if (OidIsValid(pinfo->collation) && OidIsValid(param->paramcollid))
439 param->paramcollid = pinfo->collation;
440
441 return (Node *) param;
442}
443
444/*
445 * Search for a function parameter of the given name; if there is one,
446 * construct and return a Param node for it. If not, return NULL.
447 * Helper function for sql_fn_post_column_ref.
448 */
449static Node *
450sql_fn_resolve_param_name(SQLFunctionParseInfoPtr pinfo,
451 const char *paramname, int location)
452{
453 int i;
454
455 if (pinfo->argnames == NULL)
456 return NULL;
457
458 for (i = 0; i < pinfo->nargs; i++)
459 {
460 if (pinfo->argnames[i] && strcmp(pinfo->argnames[i], paramname) == 0)
461 return sql_fn_make_param(pinfo, i + 1, location);
462 }
463
464 return NULL;
465}
466
467/*
468 * Set up the per-query execution_state records for a SQL function.
469 *
470 * The input is a List of Lists of parsed and rewritten, but not planned,
471 * querytrees. The sublist structure denotes the original query boundaries.
472 */
473static List *
474init_execution_state(List *queryTree_list,
475 SQLFunctionCachePtr fcache,
476 bool lazyEvalOK)
477{
478 List *eslist = NIL;
479 execution_state *lasttages = NULL;
480 ListCell *lc1;
481
482 foreach(lc1, queryTree_list)
483 {
484 List *qtlist = lfirst_node(List, lc1);
485 execution_state *firstes = NULL;
486 execution_state *preves = NULL;
487 ListCell *lc2;
488
489 foreach(lc2, qtlist)
490 {
491 Query *queryTree = lfirst_node(Query, lc2);
492 PlannedStmt *stmt;
493 execution_state *newes;
494
495 /* Plan the query if needed */
496 if (queryTree->commandType == CMD_UTILITY)
497 {
498 /* Utility commands require no planning. */
499 stmt = makeNode(PlannedStmt);
500 stmt->commandType = CMD_UTILITY;
501 stmt->canSetTag = queryTree->canSetTag;
502 stmt->utilityStmt = queryTree->utilityStmt;
503 stmt->stmt_location = queryTree->stmt_location;
504 stmt->stmt_len = queryTree->stmt_len;
505 }
506 else
507 stmt = pg_plan_query(queryTree,
508 CURSOR_OPT_PARALLEL_OK,
509 NULL);
510
511 /*
512 * Precheck all commands for validity in a function. This should
513 * generally match the restrictions spi.c applies.
514 */
515 if (stmt->commandType == CMD_UTILITY)
516 {
517 if (IsA(stmt->utilityStmt, CopyStmt) &&
518 ((CopyStmt *) stmt->utilityStmt)->filename == NULL)
519 ereport(ERROR,
520 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
521 errmsg("cannot COPY to/from client in a SQL function")));
522
523 if (IsA(stmt->utilityStmt, TransactionStmt))
524 ereport(ERROR,
525 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
526 /* translator: %s is a SQL statement name */
527 errmsg("%s is not allowed in a SQL function",
528 CreateCommandTag(stmt->utilityStmt))));
529 }
530
531 if (fcache->readonly_func && !CommandIsReadOnly(stmt))
532 ereport(ERROR,
533 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
534 /* translator: %s is a SQL statement name */
535 errmsg("%s is not allowed in a non-volatile function",
536 CreateCommandTag((Node *) stmt))));
537
538 if (IsInParallelMode() && !CommandIsReadOnly(stmt))
539 PreventCommandIfParallelMode(CreateCommandTag((Node *) stmt));
540
541 /* OK, build the execution_state for this query */
542 newes = (execution_state *) palloc(sizeof(execution_state));
543 if (preves)
544 preves->next = newes;
545 else
546 firstes = newes;
547
548 newes->next = NULL;
549 newes->status = F_EXEC_START;
550 newes->setsResult = false; /* might change below */
551 newes->lazyEval = false; /* might change below */
552 newes->stmt = stmt;
553 newes->qd = NULL;
554
555 if (queryTree->canSetTag)
556 lasttages = newes;
557
558 preves = newes;
559 }
560
561 eslist = lappend(eslist, firstes);
562 }
563
564 /*
565 * Mark the last canSetTag query as delivering the function result; then,
566 * if it is a plain SELECT, mark it for lazy evaluation. If it's not a
567 * SELECT we must always run it to completion.
568 *
569 * Note: at some point we might add additional criteria for whether to use
570 * lazy eval. However, we should prefer to use it whenever the function
571 * doesn't return set, since fetching more than one row is useless in that
572 * case.
573 *
574 * Note: don't set setsResult if the function returns VOID, as evidenced
575 * by not having made a junkfilter. This ensures we'll throw away any
576 * output from the last statement in such a function.
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 */
593static void
594init_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",
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, and
639 * for use as memory context identifier
640 */
641 fcache->fname = pstrdup(NameStr(procedureStruct->proname));
642 MemoryContextSetIdentifier(fcontext, fcache->fname);
643
644 /*
645 * get the result type from the procedure tuple, and check for polymorphic
646 * result type; if so, find out the actual result type.
647 */
648 rettype = procedureStruct->prorettype;
649
650 if (IsPolymorphicType(rettype))
651 {
652 rettype = get_fn_expr_rettype(finfo);
653 if (rettype == InvalidOid) /* this probably should not happen */
654 ereport(ERROR,
655 (errcode(ERRCODE_DATATYPE_MISMATCH),
656 errmsg("could not determine actual result type for function declared to return type %s",
657 format_type_be(procedureStruct->prorettype))));
658 }
659
660 fcache->rettype = rettype;
661
662 /* Fetch the typlen and byval info for the result type */
663 get_typlenbyval(rettype, &fcache->typlen, &fcache->typbyval);
664
665 /* Remember whether we're returning setof something */
666 fcache->returnsSet = procedureStruct->proretset;
667
668 /* Remember if function is STABLE/IMMUTABLE */
669 fcache->readonly_func =
670 (procedureStruct->provolatile != PROVOLATILE_VOLATILE);
671
672 /*
673 * We need the actual argument types to pass to the parser. Also make
674 * sure that parameter symbols are considered to have the function's
675 * resolved input collation.
676 */
677 fcache->pinfo = prepare_sql_fn_parse_info(procedureTuple,
678 finfo->fn_expr,
679 collation);
680
681 /*
682 * And of course we need the function body text.
683 */
684 tmp = SysCacheGetAttr(PROCOID,
685 procedureTuple,
686 Anum_pg_proc_prosrc,
687 &isNull);
688 if (isNull)
689 elog(ERROR, "null prosrc for function %u", foid);
690 fcache->src = TextDatumGetCString(tmp);
691
692 /*
693 * Parse and rewrite the queries in the function text. Use sublists to
694 * keep track of the original query boundaries. But we also build a
695 * "flat" list of the rewritten queries to pass to check_sql_fn_retval.
696 * This is because the last canSetTag query determines the result type
697 * independently of query boundaries --- and it might not be in the last
698 * sublist, for example if the last query rewrites to DO INSTEAD NOTHING.
699 * (It might not be unreasonable to throw an error in such a case, but
700 * this is the historical behavior and it doesn't seem worth changing.)
701 *
702 * Note: since parsing and planning is done in fcontext, we will generate
703 * a lot of cruft that lives as long as the fcache does. This is annoying
704 * but we'll not worry about it until the module is rewritten to use
705 * plancache.c.
706 */
707 raw_parsetree_list = pg_parse_query(fcache->src);
708
709 queryTree_list = NIL;
710 flat_query_list = NIL;
711 foreach(lc, raw_parsetree_list)
712 {
713 RawStmt *parsetree = lfirst_node(RawStmt, lc);
714 List *queryTree_sublist;
715
716 queryTree_sublist = pg_analyze_and_rewrite_params(parsetree,
717 fcache->src,
718 (ParserSetupHook) sql_fn_parser_setup,
719 fcache->pinfo,
720 NULL);
721 queryTree_list = lappend(queryTree_list, queryTree_sublist);
722 flat_query_list = list_concat(flat_query_list,
723 list_copy(queryTree_sublist));
724 }
725
726 check_sql_fn_statements(flat_query_list);
727
728 /*
729 * Check that the function returns the type it claims to. Although in
730 * simple cases this was already done when the function was defined, we
731 * have to recheck because database objects used in the function's queries
732 * might have changed type. We'd have to do it anyway if the function had
733 * any polymorphic arguments.
734 *
735 * Note: we set fcache->returnsTuple according to whether we are returning
736 * the whole tuple result or just a single column. In the latter case we
737 * clear returnsTuple because we need not act different from the scalar
738 * result case, even if it's a rowtype column. (However, we have to force
739 * lazy eval mode in that case; otherwise we'd need extra code to expand
740 * the rowtype column into multiple columns, since we have no way to
741 * notify the caller that it should do that.)
742 *
743 * check_sql_fn_retval will also construct a JunkFilter we can use to
744 * coerce the returned rowtype to the desired form (unless the result type
745 * is VOID, in which case there's nothing to coerce to).
746 */
747 fcache->returnsTuple = check_sql_fn_retval(foid,
748 rettype,
749 flat_query_list,
750 NULL,
751 &fcache->junkFilter);
752
753 if (fcache->returnsTuple)
754 {
755 /* Make sure output rowtype is properly blessed */
756 BlessTupleDesc(fcache->junkFilter->jf_resultSlot->tts_tupleDescriptor);
757 }
758 else if (fcache->returnsSet && type_is_rowtype(fcache->rettype))
759 {
760 /*
761 * Returning rowtype as if it were scalar --- materialize won't work.
762 * Right now it's sufficient to override any caller preference for
763 * materialize mode, but to add more smarts in init_execution_state
764 * about this, we'd probably need a three-way flag instead of bool.
765 */
766 lazyEvalOK = true;
767 }
768
769 /* Finally, plan the queries */
770 fcache->func_state = init_execution_state(queryTree_list,
771 fcache,
772 lazyEvalOK);
773
774 /* Mark fcache with time of creation to show it's valid */
775 fcache->lxid = MyProc->lxid;
776 fcache->subxid = GetCurrentSubTransactionId();
777
778 ReleaseSysCache(procedureTuple);
779
780 MemoryContextSwitchTo(oldcontext);
781}
782
783/* Start up execution of one execution_state node */
784static void
785postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
786{
787 DestReceiver *dest;
788
789 Assert(es->qd == NULL);
790
791 /* Caller should have ensured a suitable snapshot is active */
792 Assert(ActiveSnapshotSet());
793
794 /*
795 * If this query produces the function result, send its output to the
796 * tuplestore; else discard any output.
797 */
798 if (es->setsResult)
799 {
800 DR_sqlfunction *myState;
801
802 dest = CreateDestReceiver(DestSQLFunction);
803 /* pass down the needed info to the dest receiver routines */
804 myState = (DR_sqlfunction *) dest;
805 Assert(myState->pub.mydest == DestSQLFunction);
806 myState->tstore = fcache->tstore;
807 myState->cxt = CurrentMemoryContext;
808 myState->filter = fcache->junkFilter;
809 }
810 else
811 dest = None_Receiver;
812
813 es->qd = CreateQueryDesc(es->stmt,
814 fcache->src,
815 GetActiveSnapshot(),
816 InvalidSnapshot,
817 dest,
818 fcache->paramLI,
819 es->qd ? es->qd->queryEnv : NULL,
820 0);
821
822 /* Utility commands don't need Executor. */
823 if (es->qd->operation != CMD_UTILITY)
824 {
825 /*
826 * In lazyEval mode, do not let the executor set up an AfterTrigger
827 * context. This is necessary not just an optimization, because we
828 * mustn't exit from the function execution with a stacked
829 * AfterTrigger level still active. We are careful not to select
830 * lazyEval mode for any statement that could possibly queue triggers.
831 */
832 int eflags;
833
834 if (es->lazyEval)
835 eflags = EXEC_FLAG_SKIP_TRIGGERS;
836 else
837 eflags = 0; /* default run-to-completion flags */
838 ExecutorStart(es->qd, eflags);
839 }
840
841 es->status = F_EXEC_RUN;
842}
843
844/* Run one execution_state; either to completion or to first result row */
845/* Returns true if we ran to completion */
846static bool
847postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache)
848{
849 bool result;
850
851 if (es->qd->operation == CMD_UTILITY)
852 {
853 ProcessUtility(es->qd->plannedstmt,
854 fcache->src,
855 PROCESS_UTILITY_QUERY,
856 es->qd->params,
857 es->qd->queryEnv,
858 es->qd->dest,
859 NULL);
860 result = true; /* never stops early */
861 }
862 else
863 {
864 /* Run regular commands to completion unless lazyEval */
865 uint64 count = (es->lazyEval) ? 1 : 0;
866
867 ExecutorRun(es->qd, ForwardScanDirection, count, !fcache->returnsSet || !es->lazyEval);
868
869 /*
870 * If we requested run to completion OR there was no tuple returned,
871 * command must be complete.
872 */
873 result = (count == 0 || es->qd->estate->es_processed == 0);
874 }
875
876 return result;
877}
878
879/* Shut down execution of one execution_state node */
880static void
881postquel_end(execution_state *es)
882{
883 /* mark status done to ensure we don't do ExecutorEnd twice */
884 es->status = F_EXEC_DONE;
885
886 /* Utility commands don't need Executor. */
887 if (es->qd->operation != CMD_UTILITY)
888 {
889 ExecutorFinish(es->qd);
890 ExecutorEnd(es->qd);
891 }
892
893 es->qd->dest->rDestroy(es->qd->dest);
894
895 FreeQueryDesc(es->qd);
896 es->qd = NULL;
897}
898
899/* Build ParamListInfo array representing current arguments */
900static void
901postquel_sub_params(SQLFunctionCachePtr fcache,
902 FunctionCallInfo fcinfo)
903{
904 int nargs = fcinfo->nargs;
905
906 if (nargs > 0)
907 {
908 ParamListInfo paramLI;
909
910 if (fcache->paramLI == NULL)
911 {
912 paramLI = makeParamList(nargs);
913 fcache->paramLI = paramLI;
914 }
915 else
916 {
917 paramLI = fcache->paramLI;
918 Assert(paramLI->numParams == nargs);
919 }
920
921 for (int i = 0; i < nargs; i++)
922 {
923 ParamExternData *prm = &paramLI->params[i];
924
925 prm->value = fcinfo->args[i].value;
926 prm->isnull = fcinfo->args[i].isnull;
927 prm->pflags = 0;
928 prm->ptype = fcache->pinfo->argtypes[i];
929 }
930 }
931 else
932 fcache->paramLI = NULL;
933}
934
935/*
936 * Extract the SQL function's value from a single result row. This is used
937 * both for scalar (non-set) functions and for each row of a lazy-eval set
938 * result.
939 */
940static Datum
941postquel_get_single_result(TupleTableSlot *slot,
942 FunctionCallInfo fcinfo,
943 SQLFunctionCachePtr fcache,
944 MemoryContext resultcontext)
945{
946 Datum value;
947 MemoryContext oldcontext;
948
949 /*
950 * Set up to return the function value. For pass-by-reference datatypes,
951 * be sure to allocate the result in resultcontext, not the current memory
952 * context (which has query lifespan). We can't leave the data in the
953 * TupleTableSlot because we intend to clear the slot before returning.
954 */
955 oldcontext = MemoryContextSwitchTo(resultcontext);
956
957 if (fcache->returnsTuple)
958 {
959 /* We must return the whole tuple as a Datum. */
960 fcinfo->isnull = false;
961 value = ExecFetchSlotHeapTupleDatum(slot);
962 }
963 else
964 {
965 /*
966 * Returning a scalar, which we have to extract from the first column
967 * of the SELECT result, and then copy into result context if needed.
968 */
969 value = slot_getattr(slot, 1, &(fcinfo->isnull));
970
971 if (!fcinfo->isnull)
972 value = datumCopy(value, fcache->typbyval, fcache->typlen);
973 }
974
975 MemoryContextSwitchTo(oldcontext);
976
977 return value;
978}
979
980/*
981 * fmgr_sql: function call manager for SQL functions
982 */
983Datum
984fmgr_sql(PG_FUNCTION_ARGS)
985{
986 SQLFunctionCachePtr fcache;
987 ErrorContextCallback sqlerrcontext;
988 MemoryContext oldcontext;
989 bool randomAccess;
990 bool lazyEvalOK;
991 bool is_first;
992 bool pushed_snapshot;
993 execution_state *es;
994 TupleTableSlot *slot;
995 Datum result;
996 List *eslist;
997 ListCell *eslc;
998
999 /*
1000 * Setup error traceback support for ereport()
1001 */
1002 sqlerrcontext.callback = sql_exec_error_callback;
1003 sqlerrcontext.arg = fcinfo->flinfo;
1004 sqlerrcontext.previous = error_context_stack;
1005 error_context_stack = &sqlerrcontext;
1006
1007 /* Check call context */
1008 if (fcinfo->flinfo->fn_retset)
1009 {
1010 ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
1011
1012 /*
1013 * For simplicity, we require callers to support both set eval modes.
1014 * There are cases where we must use one or must use the other, and
1015 * it's not really worthwhile to postpone the check till we know. But
1016 * note we do not require caller to provide an expectedDesc.
1017 */
1018 if (!rsi || !IsA(rsi, ReturnSetInfo) ||
1019 (rsi->allowedModes & SFRM_ValuePerCall) == 0 ||
1020 (rsi->allowedModes & SFRM_Materialize) == 0)
1021 ereport(ERROR,
1022 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1023 errmsg("set-valued function called in context that cannot accept a set")));
1024 randomAccess = rsi->allowedModes & SFRM_Materialize_Random;
1025 lazyEvalOK = !(rsi->allowedModes & SFRM_Materialize_Preferred);
1026 }
1027 else
1028 {
1029 randomAccess = false;
1030 lazyEvalOK = true;
1031 }
1032
1033 /*
1034 * Initialize fcache (build plans) if first time through; or re-initialize
1035 * if the cache is stale.
1036 */
1037 fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
1038
1039 if (fcache != NULL)
1040 {
1041 if (fcache->lxid != MyProc->lxid ||
1042 !SubTransactionIsActive(fcache->subxid))
1043 {
1044 /* It's stale; unlink and delete */
1045 fcinfo->flinfo->fn_extra = NULL;
1046 MemoryContextDelete(fcache->fcontext);
1047 fcache = NULL;
1048 }
1049 }
1050
1051 if (fcache == NULL)
1052 {
1053 init_sql_fcache(fcinfo->flinfo, PG_GET_COLLATION(), lazyEvalOK);
1054 fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
1055 }
1056
1057 /*
1058 * Switch to context in which the fcache lives. This ensures that our
1059 * tuplestore etc will have sufficient lifetime. The sub-executor is
1060 * responsible for deleting per-tuple information. (XXX in the case of a
1061 * long-lived FmgrInfo, this policy represents more memory leakage, but
1062 * it's not entirely clear where to keep stuff instead.)
1063 */
1064 oldcontext = MemoryContextSwitchTo(fcache->fcontext);
1065
1066 /*
1067 * Find first unfinished query in function, and note whether it's the
1068 * first query.
1069 */
1070 eslist = fcache->func_state;
1071 es = NULL;
1072 is_first = true;
1073 foreach(eslc, eslist)
1074 {
1075 es = (execution_state *) lfirst(eslc);
1076
1077 while (es && es->status == F_EXEC_DONE)
1078 {
1079 is_first = false;
1080 es = es->next;
1081 }
1082
1083 if (es)
1084 break;
1085 }
1086
1087 /*
1088 * Convert params to appropriate format if starting a fresh execution. (If
1089 * continuing execution, we can re-use prior params.)
1090 */
1091 if (is_first && es && es->status == F_EXEC_START)
1092 postquel_sub_params(fcache, fcinfo);
1093
1094 /*
1095 * Build tuplestore to hold results, if we don't have one already. Note
1096 * it's in the query-lifespan context.
1097 */
1098 if (!fcache->tstore)
1099 fcache->tstore = tuplestore_begin_heap(randomAccess, false, work_mem);
1100
1101 /*
1102 * Execute each command in the function one after another until we either
1103 * run out of commands or get a result row from a lazily-evaluated SELECT.
1104 *
1105 * Notes about snapshot management:
1106 *
1107 * In a read-only function, we just use the surrounding query's snapshot.
1108 *
1109 * In a non-read-only function, we rely on the fact that we'll never
1110 * suspend execution between queries of the function: the only reason to
1111 * suspend execution before completion is if we are returning a row from a
1112 * lazily-evaluated SELECT. So, when first entering this loop, we'll
1113 * either start a new query (and push a fresh snapshot) or re-establish
1114 * the active snapshot from the existing query descriptor. If we need to
1115 * start a new query in a subsequent execution of the loop, either we need
1116 * a fresh snapshot (and pushed_snapshot is false) or the existing
1117 * snapshot is on the active stack and we can just bump its command ID.
1118 */
1119 pushed_snapshot = false;
1120 while (es)
1121 {
1122 bool completed;
1123
1124 if (es->status == F_EXEC_START)
1125 {
1126 /*
1127 * If not read-only, be sure to advance the command counter for
1128 * each command, so that all work to date in this transaction is
1129 * visible. Take a new snapshot if we don't have one yet,
1130 * otherwise just bump the command ID in the existing snapshot.
1131 */
1132 if (!fcache->readonly_func)
1133 {
1134 CommandCounterIncrement();
1135 if (!pushed_snapshot)
1136 {
1137 PushActiveSnapshot(GetTransactionSnapshot());
1138 pushed_snapshot = true;
1139 }
1140 else
1141 UpdateActiveSnapshotCommandId();
1142 }
1143
1144 postquel_start(es, fcache);
1145 }
1146 else if (!fcache->readonly_func && !pushed_snapshot)
1147 {
1148 /* Re-establish active snapshot when re-entering function */
1149 PushActiveSnapshot(es->qd->snapshot);
1150 pushed_snapshot = true;
1151 }
1152
1153 completed = postquel_getnext(es, fcache);
1154
1155 /*
1156 * If we ran the command to completion, we can shut it down now. Any
1157 * row(s) we need to return are safely stashed in the tuplestore, and
1158 * we want to be sure that, for example, AFTER triggers get fired
1159 * before we return anything. Also, if the function doesn't return
1160 * set, we can shut it down anyway because it must be a SELECT and we
1161 * don't care about fetching any more result rows.
1162 */
1163 if (completed || !fcache->returnsSet)
1164 postquel_end(es);
1165
1166 /*
1167 * Break from loop if we didn't shut down (implying we got a
1168 * lazily-evaluated row). Otherwise we'll press on till the whole
1169 * function is done, relying on the tuplestore to keep hold of the
1170 * data to eventually be returned. This is necessary since an
1171 * INSERT/UPDATE/DELETE RETURNING that sets the result might be
1172 * followed by additional rule-inserted commands, and we want to
1173 * finish doing all those commands before we return anything.
1174 */
1175 if (es->status != F_EXEC_DONE)
1176 break;
1177
1178 /*
1179 * Advance to next execution_state, which might be in the next list.
1180 */
1181 es = es->next;
1182 while (!es)
1183 {
1184 eslc = lnext(eslc);
1185 if (!eslc)
1186 break; /* end of function */
1187
1188 es = (execution_state *) lfirst(eslc);
1189
1190 /*
1191 * Flush the current snapshot so that we will take a new one for
1192 * the new query list. This ensures that new snaps are taken at
1193 * original-query boundaries, matching the behavior of interactive
1194 * execution.
1195 */
1196 if (pushed_snapshot)
1197 {
1198 PopActiveSnapshot();
1199 pushed_snapshot = false;
1200 }
1201 }
1202 }
1203
1204 /*
1205 * The tuplestore now contains whatever row(s) we are supposed to return.
1206 */
1207 if (fcache->returnsSet)
1208 {
1209 ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
1210
1211 if (es)
1212 {
1213 /*
1214 * If we stopped short of being done, we must have a lazy-eval
1215 * row.
1216 */
1217 Assert(es->lazyEval);
1218 /* Re-use the junkfilter's output slot to fetch back the tuple */
1219 Assert(fcache->junkFilter);
1220 slot = fcache->junkFilter->jf_resultSlot;
1221 if (!tuplestore_gettupleslot(fcache->tstore, true, false, slot))
1222 elog(ERROR, "failed to fetch lazy-eval tuple");
1223 /* Extract the result as a datum, and copy out from the slot */
1224 result = postquel_get_single_result(slot, fcinfo,
1225 fcache, oldcontext);
1226 /* Clear the tuplestore, but keep it for next time */
1227 /* NB: this might delete the slot's content, but we don't care */
1228 tuplestore_clear(fcache->tstore);
1229
1230 /*
1231 * Let caller know we're not finished.
1232 */
1233 rsi->isDone = ExprMultipleResult;
1234
1235 /*
1236 * Ensure we will get shut down cleanly if the exprcontext is not
1237 * run to completion.
1238 */
1239 if (!fcache->shutdown_reg)
1240 {
1241 RegisterExprContextCallback(rsi->econtext,
1242 ShutdownSQLFunction,
1243 PointerGetDatum(fcache));
1244 fcache->shutdown_reg = true;
1245 }
1246 }
1247 else if (fcache->lazyEval)
1248 {
1249 /*
1250 * We are done with a lazy evaluation. Clean up.
1251 */
1252 tuplestore_clear(fcache->tstore);
1253
1254 /*
1255 * Let caller know we're finished.
1256 */
1257 rsi->isDone = ExprEndResult;
1258
1259 fcinfo->isnull = true;
1260 result = (Datum) 0;
1261
1262 /* Deregister shutdown callback, if we made one */
1263 if (fcache->shutdown_reg)
1264 {
1265 UnregisterExprContextCallback(rsi->econtext,
1266 ShutdownSQLFunction,
1267 PointerGetDatum(fcache));
1268 fcache->shutdown_reg = false;
1269 }
1270 }
1271 else
1272 {
1273 /*
1274 * We are done with a non-lazy evaluation. Return whatever is in
1275 * the tuplestore. (It is now caller's responsibility to free the
1276 * tuplestore when done.)
1277 */
1278 rsi->returnMode = SFRM_Materialize;
1279 rsi->setResult = fcache->tstore;
1280 fcache->tstore = NULL;
1281 /* must copy desc because execSRF.c will free it */
1282 if (fcache->junkFilter)
1283 rsi->setDesc = CreateTupleDescCopy(fcache->junkFilter->jf_cleanTupType);
1284
1285 fcinfo->isnull = true;
1286 result = (Datum) 0;
1287
1288 /* Deregister shutdown callback, if we made one */
1289 if (fcache->shutdown_reg)
1290 {
1291 UnregisterExprContextCallback(rsi->econtext,
1292 ShutdownSQLFunction,
1293 PointerGetDatum(fcache));
1294 fcache->shutdown_reg = false;
1295 }
1296 }
1297 }
1298 else
1299 {
1300 /*
1301 * Non-set function. If we got a row, return it; else return NULL.
1302 */
1303 if (fcache->junkFilter)
1304 {
1305 /* Re-use the junkfilter's output slot to fetch back the tuple */
1306 slot = fcache->junkFilter->jf_resultSlot;
1307 if (tuplestore_gettupleslot(fcache->tstore, true, false, slot))
1308 result = postquel_get_single_result(slot, fcinfo,
1309 fcache, oldcontext);
1310 else
1311 {
1312 fcinfo->isnull = true;
1313 result = (Datum) 0;
1314 }
1315 }
1316 else
1317 {
1318 /* Should only get here for VOID functions and procedures */
1319 Assert(fcache->rettype == VOIDOID);
1320 fcinfo->isnull = true;
1321 result = (Datum) 0;
1322 }
1323
1324 /* Clear the tuplestore, but keep it for next time */
1325 tuplestore_clear(fcache->tstore);
1326 }
1327
1328 /* Pop snapshot if we have pushed one */
1329 if (pushed_snapshot)
1330 PopActiveSnapshot();
1331
1332 /*
1333 * If we've gone through every command in the function, we are done. Reset
1334 * the execution states to start over again on next call.
1335 */
1336 if (es == NULL)
1337 {
1338 foreach(eslc, fcache->func_state)
1339 {
1340 es = (execution_state *) lfirst(eslc);
1341 while (es)
1342 {
1343 es->status = F_EXEC_START;
1344 es = es->next;
1345 }
1346 }
1347 }
1348
1349 error_context_stack = sqlerrcontext.previous;
1350
1351 MemoryContextSwitchTo(oldcontext);
1352
1353 return result;
1354}
1355
1356
1357/*
1358 * error context callback to let us supply a call-stack traceback
1359 */
1360static void
1361sql_exec_error_callback(void *arg)
1362{
1363 FmgrInfo *flinfo = (FmgrInfo *) arg;
1364 SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) flinfo->fn_extra;
1365 int syntaxerrposition;
1366
1367 /*
1368 * We can do nothing useful if init_sql_fcache() didn't get as far as
1369 * saving the function name
1370 */
1371 if (fcache == NULL || fcache->fname == NULL)
1372 return;
1373
1374 /*
1375 * If there is a syntax error position, convert to internal syntax error
1376 */
1377 syntaxerrposition = geterrposition();
1378 if (syntaxerrposition > 0 && fcache->src != NULL)
1379 {
1380 errposition(0);
1381 internalerrposition(syntaxerrposition);
1382 internalerrquery(fcache->src);
1383 }
1384
1385 /*
1386 * Try to determine where in the function we failed. If there is a query
1387 * with non-null QueryDesc, finger it. (We check this rather than looking
1388 * for F_EXEC_RUN state, so that errors during ExecutorStart or
1389 * ExecutorEnd are blamed on the appropriate query; see postquel_start and
1390 * postquel_end.)
1391 */
1392 if (fcache->func_state)
1393 {
1394 execution_state *es;
1395 int query_num;
1396 ListCell *lc;
1397
1398 es = NULL;
1399 query_num = 1;
1400 foreach(lc, fcache->func_state)
1401 {
1402 es = (execution_state *) lfirst(lc);
1403 while (es)
1404 {
1405 if (es->qd)
1406 {
1407 errcontext("SQL function \"%s\" statement %d",
1408 fcache->fname, query_num);
1409 break;
1410 }
1411 es = es->next;
1412 }
1413 if (es)
1414 break;
1415 query_num++;
1416 }
1417 if (es == NULL)
1418 {
1419 /*
1420 * couldn't identify a running query; might be function entry,
1421 * function exit, or between queries.
1422 */
1423 errcontext("SQL function \"%s\"", fcache->fname);
1424 }
1425 }
1426 else
1427 {
1428 /*
1429 * Assume we failed during init_sql_fcache(). (It's possible that the
1430 * function actually has an empty body, but in that case we may as
1431 * well report all errors as being "during startup".)
1432 */
1433 errcontext("SQL function \"%s\" during startup", fcache->fname);
1434 }
1435}
1436
1437
1438/*
1439 * callback function in case a function-returning-set needs to be shut down
1440 * before it has been run to completion
1441 */
1442static void
1443ShutdownSQLFunction(Datum arg)
1444{
1445 SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
1446 execution_state *es;
1447 ListCell *lc;
1448
1449 foreach(lc, fcache->func_state)
1450 {
1451 es = (execution_state *) lfirst(lc);
1452 while (es)
1453 {
1454 /* Shut down anything still running */
1455 if (es->status == F_EXEC_RUN)
1456 {
1457 /* Re-establish active snapshot for any called functions */
1458 if (!fcache->readonly_func)
1459 PushActiveSnapshot(es->qd->snapshot);
1460
1461 postquel_end(es);
1462
1463 if (!fcache->readonly_func)
1464 PopActiveSnapshot();
1465 }
1466
1467 /* Reset states to START in case we're called again */
1468 es->status = F_EXEC_START;
1469 es = es->next;
1470 }
1471 }
1472
1473 /* Release tuplestore if we have one */
1474 if (fcache->tstore)
1475 tuplestore_end(fcache->tstore);
1476 fcache->tstore = NULL;
1477
1478 /* execUtils will deregister the callback... */
1479 fcache->shutdown_reg = false;
1480}
1481
1482/*
1483 * check_sql_fn_statements
1484 *
1485 * Check statements in an SQL function. Error out if there is anything that
1486 * is not acceptable.
1487 */
1488void
1489check_sql_fn_statements(List *queryTreeList)
1490{
1491 ListCell *lc;
1492
1493 foreach(lc, queryTreeList)
1494 {
1495 Query *query = lfirst_node(Query, lc);
1496
1497 /*
1498 * Disallow procedures with output arguments. The current
1499 * implementation would just throw the output values away, unless the
1500 * statement is the last one. Per SQL standard, we should assign the
1501 * output values by name. By disallowing this here, we preserve an
1502 * opportunity for future improvement.
1503 */
1504 if (query->commandType == CMD_UTILITY &&
1505 IsA(query->utilityStmt, CallStmt))
1506 {
1507 CallStmt *stmt = castNode(CallStmt, query->utilityStmt);
1508 HeapTuple tuple;
1509 int numargs;
1510 Oid *argtypes;
1511 char **argnames;
1512 char *argmodes;
1513 int i;
1514
1515 tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(stmt->funcexpr->funcid));
1516 if (!HeapTupleIsValid(tuple))
1517 elog(ERROR, "cache lookup failed for function %u", stmt->funcexpr->funcid);
1518 numargs = get_func_arg_info(tuple, &argtypes, &argnames, &argmodes);
1519 ReleaseSysCache(tuple);
1520
1521 for (i = 0; i < numargs; i++)
1522 {
1523 if (argmodes && (argmodes[i] == PROARGMODE_INOUT || argmodes[i] == PROARGMODE_OUT))
1524 ereport(ERROR,
1525 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1526 errmsg("calling procedures with output arguments is not supported in SQL functions")));
1527 }
1528 }
1529 }
1530}
1531
1532/*
1533 * check_sql_fn_retval() -- check return value of a list of sql parse trees.
1534 *
1535 * The return value of a sql function is the value returned by the last
1536 * canSetTag query in the function. We do some ad-hoc type checking here
1537 * to be sure that the user is returning the type he claims. There are
1538 * also a couple of strange-looking features to assist callers in dealing
1539 * with allowed special cases, such as binary-compatible result types.
1540 *
1541 * For a polymorphic function the passed rettype must be the actual resolved
1542 * output type of the function; we should never see a polymorphic pseudotype
1543 * such as ANYELEMENT as rettype. (This means we can't check the type during
1544 * function definition of a polymorphic function.)
1545 *
1546 * This function returns true if the sql function returns the entire tuple
1547 * result of its final statement, or false if it returns just the first column
1548 * result of that statement. It throws an error if the final statement doesn't
1549 * return the right type at all.
1550 *
1551 * Note that because we allow "SELECT rowtype_expression", the result can be
1552 * false even when the declared function return type is a rowtype.
1553 *
1554 * If modifyTargetList isn't NULL, the function will modify the final
1555 * statement's targetlist in two cases:
1556 * (1) if the tlist returns values that are binary-coercible to the expected
1557 * type rather than being exactly the expected type. RelabelType nodes will
1558 * be inserted to make the result types match exactly.
1559 * (2) if there are dropped columns in the declared result rowtype. NULL
1560 * output columns will be inserted in the tlist to match them.
1561 * (Obviously the caller must pass a parsetree that is okay to modify when
1562 * using this flag.) Note that this flag does not affect whether the tlist is
1563 * considered to be a legal match to the result type, only how we react to
1564 * allowed not-exact-match cases. *modifyTargetList will be set true iff
1565 * we had to make any "dangerous" changes that could modify the semantics of
1566 * the statement. If it is set true, the caller should not use the modified
1567 * statement, but for simplicity we apply the changes anyway.
1568 *
1569 * If junkFilter isn't NULL, then *junkFilter is set to a JunkFilter defined
1570 * to convert the function's tuple result to the correct output tuple type.
1571 * Exception: if the function is defined to return VOID then *junkFilter is
1572 * set to NULL.
1573 */
1574bool
1575check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
1576 bool *modifyTargetList,
1577 JunkFilter **junkFilter)
1578{
1579 Query *parse;
1580 List **tlist_ptr;
1581 List *tlist;
1582 int tlistlen;
1583 char fn_typtype;
1584 Oid restype;
1585 ListCell *lc;
1586
1587 AssertArg(!IsPolymorphicType(rettype));
1588
1589 if (modifyTargetList)
1590 *modifyTargetList = false; /* initialize for no change */
1591 if (junkFilter)
1592 *junkFilter = NULL; /* initialize in case of VOID result */
1593
1594 /*
1595 * If it's declared to return VOID, we don't care what's in the function.
1596 * (This takes care of the procedure case, as well.)
1597 */
1598 if (rettype == VOIDOID)
1599 return false;
1600
1601 /*
1602 * Find the last canSetTag query in the list. This isn't necessarily the
1603 * last parsetree, because rule rewriting can insert queries after what
1604 * the user wrote.
1605 */
1606 parse = NULL;
1607 foreach(lc, queryTreeList)
1608 {
1609 Query *q = lfirst_node(Query, lc);
1610
1611 if (q->canSetTag)
1612 parse = q;
1613 }
1614
1615 /*
1616 * If it's a plain SELECT, it returns whatever the targetlist says.
1617 * Otherwise, if it's INSERT/UPDATE/DELETE with RETURNING, it returns
1618 * that. Otherwise, the function return type must be VOID.
1619 *
1620 * Note: eventually replace this test with QueryReturnsTuples? We'd need
1621 * a more general method of determining the output type, though. Also, it
1622 * seems too dangerous to consider FETCH or EXECUTE as returning a
1623 * determinable rowtype, since they depend on relatively short-lived
1624 * entities.
1625 */
1626 if (parse &&
1627 parse->commandType == CMD_SELECT)
1628 {
1629 tlist_ptr = &parse->targetList;
1630 tlist = parse->targetList;
1631 }
1632 else if (parse &&
1633 (parse->commandType == CMD_INSERT ||
1634 parse->commandType == CMD_UPDATE ||
1635 parse->commandType == CMD_DELETE) &&
1636 parse->returningList)
1637 {
1638 tlist_ptr = &parse->returningList;
1639 tlist = parse->returningList;
1640 }
1641 else
1642 {
1643 /* Empty function body, or last statement is a utility command */
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("Function's final statement must be SELECT or INSERT/UPDATE/DELETE RETURNING.")));
1649 return false; /* keep compiler quiet */
1650 }
1651
1652 /*
1653 * OK, check that the targetlist returns something matching the declared
1654 * type.
1655 */
1656
1657 /*
1658 * Count the non-junk entries in the result targetlist.
1659 */
1660 tlistlen = ExecCleanTargetListLength(tlist);
1661
1662 fn_typtype = get_typtype(rettype);
1663
1664 if (fn_typtype == TYPTYPE_BASE ||
1665 fn_typtype == TYPTYPE_DOMAIN ||
1666 fn_typtype == TYPTYPE_ENUM ||
1667 fn_typtype == TYPTYPE_RANGE)
1668 {
1669 /*
1670 * For scalar-type returns, the target list must have exactly one
1671 * non-junk entry, and its type must agree with what the user
1672 * declared; except we allow binary-compatible types too.
1673 */
1674 TargetEntry *tle;
1675
1676 if (tlistlen != 1)
1677 ereport(ERROR,
1678 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1679 errmsg("return type mismatch in function declared to return %s",
1680 format_type_be(rettype)),
1681 errdetail("Final statement must return exactly one column.")));
1682
1683 /* We assume here that non-junk TLEs must come first in tlists */
1684 tle = (TargetEntry *) linitial(tlist);
1685 Assert(!tle->resjunk);
1686
1687 restype = exprType((Node *) tle->expr);
1688 if (!IsBinaryCoercible(restype, rettype))
1689 ereport(ERROR,
1690 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1691 errmsg("return type mismatch in function declared to return %s",
1692 format_type_be(rettype)),
1693 errdetail("Actual return type is %s.",
1694 format_type_be(restype))));
1695 if (modifyTargetList && restype != rettype)
1696 {
1697 tle->expr = (Expr *) makeRelabelType(tle->expr,
1698 rettype,
1699 -1,
1700 get_typcollation(rettype),
1701 COERCE_IMPLICIT_CAST);
1702 /* Relabel is dangerous if TLE is a sort/group or setop column */
1703 if (tle->ressortgroupref != 0 || parse->setOperations)
1704 *modifyTargetList = true;
1705 }
1706
1707 /* Set up junk filter if needed */
1708 if (junkFilter)
1709 *junkFilter = ExecInitJunkFilter(tlist,
1710 MakeSingleTupleTableSlot(NULL, &TTSOpsMinimalTuple));
1711 }
1712 else if (fn_typtype == TYPTYPE_COMPOSITE || rettype == RECORDOID)
1713 {
1714 /*
1715 * Returns a rowtype.
1716 *
1717 * Note that we will not consider a domain over composite to be a
1718 * "rowtype" return type; it goes through the scalar case above. This
1719 * is because SQL functions don't provide any implicit casting to the
1720 * result type, so there is no way to produce a domain-over-composite
1721 * result except by computing it as an explicit single-column result.
1722 */
1723 TupleDesc tupdesc;
1724 int tupnatts; /* physical number of columns in tuple */
1725 int tuplogcols; /* # of nondeleted columns in tuple */
1726 int colindex; /* physical column index */
1727 List *newtlist; /* new non-junk tlist entries */
1728 List *junkattrs; /* new junk tlist entries */
1729
1730 /*
1731 * If the target list is of length 1, and the type of the varnode in
1732 * the target list matches the declared return type, this is okay.
1733 * This can happen, for example, where the body of the function is
1734 * 'SELECT func2()', where func2 has the same composite return type as
1735 * the function that's calling it.
1736 *
1737 * XXX Note that if rettype is RECORD, the IsBinaryCoercible check
1738 * will succeed for any composite restype. For the moment we rely on
1739 * runtime type checking to catch any discrepancy, but it'd be nice to
1740 * do better at parse time.
1741 */
1742 if (tlistlen == 1)
1743 {
1744 TargetEntry *tle = (TargetEntry *) linitial(tlist);
1745
1746 Assert(!tle->resjunk);
1747 restype = exprType((Node *) tle->expr);
1748 if (IsBinaryCoercible(restype, rettype))
1749 {
1750 if (modifyTargetList && restype != rettype)
1751 {
1752 tle->expr = (Expr *) makeRelabelType(tle->expr,
1753 rettype,
1754 -1,
1755 get_typcollation(rettype),
1756 COERCE_IMPLICIT_CAST);
1757 /* Relabel is dangerous if sort/group or setop column */
1758 if (tle->ressortgroupref != 0 || parse->setOperations)
1759 *modifyTargetList = true;
1760 }
1761 /* Set up junk filter if needed */
1762 if (junkFilter)
1763 {
1764 TupleTableSlot *slot =
1765 MakeSingleTupleTableSlot(NULL, &TTSOpsMinimalTuple);
1766
1767 *junkFilter = ExecInitJunkFilter(tlist, slot);
1768 }
1769 return false; /* NOT returning whole tuple */
1770 }
1771 }
1772
1773 /*
1774 * Is the rowtype fixed, or determined only at runtime? (Note we
1775 * cannot see TYPEFUNC_COMPOSITE_DOMAIN here.)
1776 */
1777 if (get_func_result_type(func_id, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
1778 {
1779 /*
1780 * Assume we are returning the whole tuple. Crosschecking against
1781 * what the caller expects will happen at runtime.
1782 */
1783 if (junkFilter)
1784 {
1785 TupleTableSlot *slot;
1786
1787 slot = MakeSingleTupleTableSlot(NULL, &TTSOpsMinimalTuple);
1788 *junkFilter = ExecInitJunkFilter(tlist, slot);
1789 }
1790 return true;
1791 }
1792 Assert(tupdesc);
1793
1794 /*
1795 * Verify that the targetlist matches the return tuple type. We scan
1796 * the non-deleted attributes to ensure that they match the datatypes
1797 * of the non-resjunk columns. For deleted attributes, insert NULL
1798 * result columns if the caller asked for that.
1799 */
1800 tupnatts = tupdesc->natts;
1801 tuplogcols = 0; /* we'll count nondeleted cols as we go */
1802 colindex = 0;
1803 newtlist = NIL; /* these are only used if modifyTargetList */
1804 junkattrs = NIL;
1805
1806 foreach(lc, tlist)
1807 {
1808 TargetEntry *tle = (TargetEntry *) lfirst(lc);
1809 Form_pg_attribute attr;
1810 Oid tletype;
1811 Oid atttype;
1812
1813 if (tle->resjunk)
1814 {
1815 if (modifyTargetList)
1816 junkattrs = lappend(junkattrs, tle);
1817 continue;
1818 }
1819
1820 do
1821 {
1822 colindex++;
1823 if (colindex > tupnatts)
1824 ereport(ERROR,
1825 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1826 errmsg("return type mismatch in function declared to return %s",
1827 format_type_be(rettype)),
1828 errdetail("Final statement returns too many columns.")));
1829 attr = TupleDescAttr(tupdesc, colindex - 1);
1830 if (attr->attisdropped && modifyTargetList)
1831 {
1832 Expr *null_expr;
1833
1834 /* The type of the null we insert isn't important */
1835 null_expr = (Expr *) makeConst(INT4OID,
1836 -1,
1837 InvalidOid,
1838 sizeof(int32),
1839 (Datum) 0,
1840 true, /* isnull */
1841 true /* byval */ );
1842 newtlist = lappend(newtlist,
1843 makeTargetEntry(null_expr,
1844 colindex,
1845 NULL,
1846 false));
1847 /* NULL insertion is dangerous in a setop */
1848 if (parse->setOperations)
1849 *modifyTargetList = true;
1850 }
1851 } while (attr->attisdropped);
1852 tuplogcols++;
1853
1854 tletype = exprType((Node *) tle->expr);
1855 atttype = attr->atttypid;
1856 if (!IsBinaryCoercible(tletype, atttype))
1857 ereport(ERROR,
1858 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1859 errmsg("return type mismatch in function declared to return %s",
1860 format_type_be(rettype)),
1861 errdetail("Final statement returns %s instead of %s at column %d.",
1862 format_type_be(tletype),
1863 format_type_be(atttype),
1864 tuplogcols)));
1865 if (modifyTargetList)
1866 {
1867 if (tletype != atttype)
1868 {
1869 tle->expr = (Expr *) makeRelabelType(tle->expr,
1870 atttype,
1871 -1,
1872 get_typcollation(atttype),
1873 COERCE_IMPLICIT_CAST);
1874 /* Relabel is dangerous if sort/group or setop column */
1875 if (tle->ressortgroupref != 0 || parse->setOperations)
1876 *modifyTargetList = true;
1877 }
1878 tle->resno = colindex;
1879 newtlist = lappend(newtlist, tle);
1880 }
1881 }
1882
1883 /* remaining columns in tupdesc had better all be dropped */
1884 for (colindex++; colindex <= tupnatts; colindex++)
1885 {
1886 if (!TupleDescAttr(tupdesc, colindex - 1)->attisdropped)
1887 ereport(ERROR,
1888 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1889 errmsg("return type mismatch in function declared to return %s",
1890 format_type_be(rettype)),
1891 errdetail("Final statement returns too few columns.")));
1892 if (modifyTargetList)
1893 {
1894 Expr *null_expr;
1895
1896 /* The type of the null we insert isn't important */
1897 null_expr = (Expr *) makeConst(INT4OID,
1898 -1,
1899 InvalidOid,
1900 sizeof(int32),
1901 (Datum) 0,
1902 true, /* isnull */
1903 true /* byval */ );
1904 newtlist = lappend(newtlist,
1905 makeTargetEntry(null_expr,
1906 colindex,
1907 NULL,
1908 false));
1909 /* NULL insertion is dangerous in a setop */
1910 if (parse->setOperations)
1911 *modifyTargetList = true;
1912 }
1913 }
1914
1915 if (modifyTargetList)
1916 {
1917 /* ensure resjunk columns are numbered correctly */
1918 foreach(lc, junkattrs)
1919 {
1920 TargetEntry *tle = (TargetEntry *) lfirst(lc);
1921
1922 tle->resno = colindex++;
1923 }
1924 /* replace the tlist with the modified one */
1925 *tlist_ptr = list_concat(newtlist, junkattrs);
1926 }
1927
1928 /* Set up junk filter if needed */
1929 if (junkFilter)
1930 {
1931 TupleTableSlot *slot =
1932 MakeSingleTupleTableSlot(NULL, &TTSOpsMinimalTuple);
1933
1934 *junkFilter = ExecInitJunkFilterConversion(tlist,
1935 CreateTupleDescCopy(tupdesc),
1936 slot);
1937 }
1938
1939 /* Report that we are returning entire tuple result */
1940 return true;
1941 }
1942 else
1943 ereport(ERROR,
1944 (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
1945 errmsg("return type %s is not supported for SQL functions",
1946 format_type_be(rettype))));
1947
1948 return false;
1949}
1950
1951
1952/*
1953 * CreateSQLFunctionDestReceiver -- create a suitable DestReceiver object
1954 */
1955DestReceiver *
1956CreateSQLFunctionDestReceiver(void)
1957{
1958 DR_sqlfunction *self = (DR_sqlfunction *) palloc0(sizeof(DR_sqlfunction));
1959
1960 self->pub.receiveSlot = sqlfunction_receive;
1961 self->pub.rStartup = sqlfunction_startup;
1962 self->pub.rShutdown = sqlfunction_shutdown;
1963 self->pub.rDestroy = sqlfunction_destroy;
1964 self->pub.mydest = DestSQLFunction;
1965
1966 /* private fields will be set by postquel_start */
1967
1968 return (DestReceiver *) self;
1969}
1970
1971/*
1972 * sqlfunction_startup --- executor startup
1973 */
1974static void
1975sqlfunction_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
1976{
1977 /* no-op */
1978}
1979
1980/*
1981 * sqlfunction_receive --- receive one tuple
1982 */
1983static bool
1984sqlfunction_receive(TupleTableSlot *slot, DestReceiver *self)
1985{
1986 DR_sqlfunction *myState = (DR_sqlfunction *) self;
1987
1988 /* Filter tuple as needed */
1989 slot = ExecFilterJunk(myState->filter, slot);
1990
1991 /* Store the filtered tuple into the tuplestore */
1992 tuplestore_puttupleslot(myState->tstore, slot);
1993
1994 return true;
1995}
1996
1997/*
1998 * sqlfunction_shutdown --- executor end
1999 */
2000static void
2001sqlfunction_shutdown(DestReceiver *self)
2002{
2003 /* no-op */
2004}
2005
2006/*
2007 * sqlfunction_destroy --- release DestReceiver object
2008 */
2009static void
2010sqlfunction_destroy(DestReceiver *self)
2011{
2012 pfree(self);
2013}
2014