1 /*-------------------------------------------------------------------------
4 * routines to support sub-selects appearing in expressions
6 * This module is concerned with executing SubPlan expression nodes, which
7 * should not be confused with sub-SELECTs appearing in FROM. SubPlans are
8 * divided into "initplans", which are those that need only one evaluation per
9 * query (among other restrictions, this requires that they don't use any
10 * direct correlation variables from the parent plan level), and "regular"
11 * subplans, which are re-evaluated every time their result is required.
14 * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
15 * Portions Copyright (c) 1994, Regents of the University of California
18 * src/backend/executor/nodeSubplan.c
20 *-------------------------------------------------------------------------
24 * ExecSubPlan - process a subselect
25 * ExecInitSubPlan - initialize a subselect
32 #include "access/htup_details.h"
33 #include "executor/executor.h"
34 #include "executor/nodeSubplan.h"
35 #include "nodes/makefuncs.h"
36 #include "optimizer/clauses.h"
37 #include "utils/array.h"
38 #include "utils/lsyscache.h"
39 #include "utils/memutils.h"
42 static Datum ExecSubPlan(SubPlanState *node,
43 ExprContext *econtext,
45 ExprDoneCond *isDone);
46 static Datum ExecAlternativeSubPlan(AlternativeSubPlanState *node,
47 ExprContext *econtext,
49 ExprDoneCond *isDone);
50 static Datum ExecHashSubPlan(SubPlanState *node,
51 ExprContext *econtext,
53 static Datum ExecScanSubPlan(SubPlanState *node,
54 ExprContext *econtext,
56 static void buildSubPlanHash(SubPlanState *node, ExprContext *econtext);
57 static bool findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
58 FmgrInfo *eqfunctions);
59 static bool slotAllNulls(TupleTableSlot *slot);
60 static bool slotNoNulls(TupleTableSlot *slot);
63 /* ----------------------------------------------------------------
66 * This is the main entry point for execution of a regular SubPlan.
67 * ----------------------------------------------------------------
70 ExecSubPlan(SubPlanState *node,
71 ExprContext *econtext,
75 SubPlan *subplan = (SubPlan *) node->xprstate.expr;
77 /* Set default values for result flags: non-null, not a set result */
80 *isDone = ExprSingleResult;
83 if (subplan->subLinkType == CTE_SUBLINK)
84 elog(ERROR, "CTE subplans should not be executed via ExecSubPlan");
85 if (subplan->setParam != NIL && subplan->subLinkType != MULTIEXPR_SUBLINK)
86 elog(ERROR, "cannot set parent params from subquery");
88 /* Select appropriate evaluation strategy */
89 if (subplan->useHashTable)
90 return ExecHashSubPlan(node, econtext, isNull);
92 return ExecScanSubPlan(node, econtext, isNull);
96 * ExecHashSubPlan: store subselect result in an in-memory hash table
99 ExecHashSubPlan(SubPlanState *node,
100 ExprContext *econtext,
103 SubPlan *subplan = (SubPlan *) node->xprstate.expr;
104 PlanState *planstate = node->planstate;
105 TupleTableSlot *slot;
107 /* Shouldn't have any direct correlation Vars */
108 if (subplan->parParam != NIL || node->args != NIL)
109 elog(ERROR, "hashed subplan with direct correlation not supported");
112 * If first time through or we need to rescan the subplan, build the hash
115 if (node->hashtable == NULL || planstate->chgParam != NULL)
116 buildSubPlanHash(node, econtext);
119 * The result for an empty subplan is always FALSE; no need to evaluate
123 if (!node->havehashrows && !node->havenullrows)
124 return BoolGetDatum(false);
127 * Evaluate lefthand expressions and form a projection tuple. First we
128 * have to set the econtext to use (hack alert!).
130 node->projLeft->pi_exprContext = econtext;
131 slot = ExecProject(node->projLeft, NULL);
134 * Note: because we are typically called in a per-tuple context, we have
135 * to explicitly clear the projected tuple before returning. Otherwise,
136 * we'll have a double-free situation: the per-tuple context will probably
137 * be reset before we're called again, and then the tuple slot will think
138 * it still needs to free the tuple.
142 * If the LHS is all non-null, probe for an exact match in the main hash
143 * table. If we find one, the result is TRUE. Otherwise, scan the
144 * partly-null table to see if there are any rows that aren't provably
145 * unequal to the LHS; if so, the result is UNKNOWN. (We skip that part
146 * if we don't care about UNKNOWN.) Otherwise, the result is FALSE.
148 * Note: the reason we can avoid a full scan of the main hash table is
149 * that the combining operators are assumed never to yield NULL when both
150 * inputs are non-null. If they were to do so, we might need to produce
151 * UNKNOWN instead of FALSE because of an UNKNOWN result in comparing the
152 * LHS to some main-table entry --- which is a comparison we will not even
153 * make, unless there's a chance match of hash keys.
155 if (slotNoNulls(slot))
157 if (node->havehashrows &&
158 FindTupleHashEntry(node->hashtable,
161 node->lhs_hash_funcs) != NULL)
163 ExecClearTuple(slot);
164 return BoolGetDatum(true);
166 if (node->havenullrows &&
167 findPartialMatch(node->hashnulls, slot, node->cur_eq_funcs))
169 ExecClearTuple(slot);
171 return BoolGetDatum(false);
173 ExecClearTuple(slot);
174 return BoolGetDatum(false);
178 * When the LHS is partly or wholly NULL, we can never return TRUE. If we
179 * don't care about UNKNOWN, just return FALSE. Otherwise, if the LHS is
180 * wholly NULL, immediately return UNKNOWN. (Since the combining
181 * operators are strict, the result could only be FALSE if the sub-select
182 * were empty, but we already handled that case.) Otherwise, we must scan
183 * both the main and partly-null tables to see if there are any rows that
184 * aren't provably unequal to the LHS; if so, the result is UNKNOWN.
185 * Otherwise, the result is FALSE.
187 if (node->hashnulls == NULL)
189 ExecClearTuple(slot);
190 return BoolGetDatum(false);
192 if (slotAllNulls(slot))
194 ExecClearTuple(slot);
196 return BoolGetDatum(false);
198 /* Scan partly-null table first, since more likely to get a match */
199 if (node->havenullrows &&
200 findPartialMatch(node->hashnulls, slot, node->cur_eq_funcs))
202 ExecClearTuple(slot);
204 return BoolGetDatum(false);
206 if (node->havehashrows &&
207 findPartialMatch(node->hashtable, slot, node->cur_eq_funcs))
209 ExecClearTuple(slot);
211 return BoolGetDatum(false);
213 ExecClearTuple(slot);
214 return BoolGetDatum(false);
218 * ExecScanSubPlan: default case where we have to rescan subplan each time
221 ExecScanSubPlan(SubPlanState *node,
222 ExprContext *econtext,
225 SubPlan *subplan = (SubPlan *) node->xprstate.expr;
226 PlanState *planstate = node->planstate;
227 SubLinkType subLinkType = subplan->subLinkType;
228 MemoryContext oldcontext;
229 TupleTableSlot *slot;
231 bool found = false; /* TRUE if got at least one subplan tuple */
234 ArrayBuildStateAny *astate = NULL;
237 * MULTIEXPR subplans, when "executed", just return NULL; but first we
238 * mark the subplan's output parameters as needing recalculation. (This
239 * is a bit of a hack: it relies on the subplan appearing later in its
240 * targetlist than any of the referencing Params, so that all the Params
241 * have been evaluated before we re-mark them for the next evaluation
242 * cycle. But in general resjunk tlist items appear after non-resjunk
243 * ones, so this should be safe.) Unlike ExecReScanSetParamPlan, we do
244 * *not* set bits in the parent plan node's chgParam, because we don't
245 * want to cause a rescan of the parent.
247 if (subLinkType == MULTIEXPR_SUBLINK)
249 EState *estate = node->parent->state;
251 foreach(l, subplan->setParam)
253 int paramid = lfirst_int(l);
254 ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
256 prm->execPlan = node;
262 /* Initialize ArrayBuildStateAny in caller's context, if needed */
263 if (subLinkType == ARRAY_SUBLINK)
264 astate = initArrayResultAny(subplan->firstColType,
265 CurrentMemoryContext);
268 * We are probably in a short-lived expression-evaluation context. Switch
269 * to the per-query context for manipulating the child plan's chgParam,
270 * calling ExecProcNode on it, etc.
272 oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
275 * Set Params of this plan from parent plan correlation values. (Any
276 * calculation we have to do is done in the parent econtext, since the
277 * Param values don't need to have per-query lifetime.)
279 Assert(list_length(subplan->parParam) == list_length(node->args));
281 forboth(l, subplan->parParam, pvar, node->args)
283 int paramid = lfirst_int(l);
284 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
286 prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar),
290 planstate->chgParam = bms_add_member(planstate->chgParam, paramid);
294 * Now that we've set up its parameters, we can reset the subplan.
296 ExecReScan(planstate);
299 * For all sublink types except EXPR_SUBLINK and ARRAY_SUBLINK, the result
300 * is boolean as are the results of the combining operators. We combine
301 * results across tuples (if the subplan produces more than one) using OR
302 * semantics for ANY_SUBLINK or AND semantics for ALL_SUBLINK.
303 * (ROWCOMPARE_SUBLINK doesn't allow multiple tuples from the subplan.)
304 * NULL results from the combining operators are handled according to the
305 * usual SQL semantics for OR and AND. The result for no input tuples is
306 * FALSE for ANY_SUBLINK, TRUE for ALL_SUBLINK, NULL for
307 * ROWCOMPARE_SUBLINK.
309 * For EXPR_SUBLINK we require the subplan to produce no more than one
310 * tuple, else an error is raised. If zero tuples are produced, we return
311 * NULL. Assuming we get a tuple, we just use its first column (there can
312 * be only one non-junk column in this case).
314 * For ARRAY_SUBLINK we allow the subplan to produce any number of tuples,
315 * and form an array of the first column's values. Note in particular
316 * that we produce a zero-element array if no tuples are produced (this is
317 * a change from pre-8.3 behavior of returning NULL).
319 result = BoolGetDatum(subLinkType == ALL_SUBLINK);
322 for (slot = ExecProcNode(planstate);
324 slot = ExecProcNode(planstate))
326 TupleDesc tdesc = slot->tts_tupleDescriptor;
332 if (subLinkType == EXISTS_SUBLINK)
335 result = BoolGetDatum(true);
339 if (subLinkType == EXPR_SUBLINK)
341 /* cannot allow multiple input tuples for EXPR sublink */
344 (errcode(ERRCODE_CARDINALITY_VIOLATION),
345 errmsg("more than one row returned by a subquery used as an expression")));
349 * We need to copy the subplan's tuple in case the result is of
350 * pass-by-ref type --- our return value will point into this
351 * copied tuple! Can't use the subplan's instance of the tuple
352 * since it won't still be valid after next ExecProcNode() call.
353 * node->curTuple keeps track of the copied tuple for eventual
357 heap_freetuple(node->curTuple);
358 node->curTuple = ExecCopySlotTuple(slot);
360 result = heap_getattr(node->curTuple, 1, tdesc, isNull);
361 /* keep scanning subplan to make sure there's only one tuple */
365 if (subLinkType == ARRAY_SUBLINK)
371 /* stash away current value */
372 Assert(subplan->firstColType == tdesc->attrs[0]->atttypid);
373 dvalue = slot_getattr(slot, 1, &disnull);
374 astate = accumArrayResultAny(astate, dvalue, disnull,
375 subplan->firstColType, oldcontext);
376 /* keep scanning subplan to collect all values */
380 /* cannot allow multiple input tuples for ROWCOMPARE sublink either */
381 if (subLinkType == ROWCOMPARE_SUBLINK && found)
383 (errcode(ERRCODE_CARDINALITY_VIOLATION),
384 errmsg("more than one row returned by a subquery used as an expression")));
389 * For ALL, ANY, and ROWCOMPARE sublinks, load up the Params
390 * representing the columns of the sub-select, and then evaluate the
391 * combining expression.
394 foreach(plst, subplan->paramIds)
396 int paramid = lfirst_int(plst);
397 ParamExecData *prmdata;
399 prmdata = &(econtext->ecxt_param_exec_vals[paramid]);
400 Assert(prmdata->execPlan == NULL);
401 prmdata->value = slot_getattr(slot, col, &(prmdata->isnull));
405 rowresult = ExecEvalExprSwitchContext(node->testexpr, econtext,
408 if (subLinkType == ANY_SUBLINK)
410 /* combine across rows per OR semantics */
413 else if (DatumGetBool(rowresult))
415 result = BoolGetDatum(true);
417 break; /* needn't look at any more rows */
420 else if (subLinkType == ALL_SUBLINK)
422 /* combine across rows per AND semantics */
425 else if (!DatumGetBool(rowresult))
427 result = BoolGetDatum(false);
429 break; /* needn't look at any more rows */
434 /* must be ROWCOMPARE_SUBLINK */
440 MemoryContextSwitchTo(oldcontext);
442 if (subLinkType == ARRAY_SUBLINK)
444 /* We return the result in the caller's context */
445 result = makeArrayResultAny(astate, oldcontext, true);
450 * deal with empty subplan result. result/isNull were previously
451 * initialized correctly for all sublink types except EXPR and
452 * ROWCOMPARE; for those, return NULL.
454 if (subLinkType == EXPR_SUBLINK ||
455 subLinkType == ROWCOMPARE_SUBLINK)
466 * buildSubPlanHash: load hash table by scanning subplan output.
469 buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
471 SubPlan *subplan = (SubPlan *) node->xprstate.expr;
472 PlanState *planstate = node->planstate;
473 int ncols = list_length(subplan->paramIds);
474 ExprContext *innerecontext = node->innerecontext;
475 MemoryContext oldcontext;
477 TupleTableSlot *slot;
479 Assert(subplan->subLinkType == ANY_SUBLINK);
482 * If we already had any hash tables, destroy 'em; then create empty hash
485 * If we need to distinguish accurately between FALSE and UNKNOWN (i.e.,
486 * NULL) results of the IN operation, then we have to store subplan output
487 * rows that are partly or wholly NULL. We store such rows in a separate
488 * hash table that we expect will be much smaller than the main table. (We
489 * can use hashing to eliminate partly-null rows that are not distinct. We
490 * keep them separate to minimize the cost of the inevitable full-table
491 * searches; see findPartialMatch.)
493 * If it's not necessary to distinguish FALSE and UNKNOWN, then we don't
494 * need to store subplan output rows that contain NULL.
496 MemoryContextReset(node->hashtablecxt);
497 node->hashtable = NULL;
498 node->hashnulls = NULL;
499 node->havehashrows = false;
500 node->havenullrows = false;
502 nbuckets = (long) Min(planstate->plan->plan_rows, (double) LONG_MAX);
506 node->hashtable = BuildTupleHashTable(ncols,
509 node->tab_hash_funcs,
511 sizeof(TupleHashEntryData),
515 if (!subplan->unknownEqFalse)
518 nbuckets = 1; /* there can only be one entry */
525 node->hashnulls = BuildTupleHashTable(ncols,
528 node->tab_hash_funcs,
530 sizeof(TupleHashEntryData),
536 * We are probably in a short-lived expression-evaluation context. Switch
537 * to the per-query context for manipulating the child plan.
539 oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
542 * Reset subplan to start.
544 ExecReScan(planstate);
547 * Scan the subplan and load the hash table(s). Note that when there are
548 * duplicate rows coming out of the sub-select, only one copy is stored.
550 for (slot = ExecProcNode(planstate);
552 slot = ExecProcNode(planstate))
559 * Load up the Params representing the raw sub-select outputs, then
560 * form the projection tuple to store in the hashtable.
562 foreach(plst, subplan->paramIds)
564 int paramid = lfirst_int(plst);
565 ParamExecData *prmdata;
567 prmdata = &(innerecontext->ecxt_param_exec_vals[paramid]);
568 Assert(prmdata->execPlan == NULL);
569 prmdata->value = slot_getattr(slot, col,
573 slot = ExecProject(node->projRight, NULL);
576 * If result contains any nulls, store separately or not at all.
578 if (slotNoNulls(slot))
580 (void) LookupTupleHashEntry(node->hashtable, slot, &isnew);
581 node->havehashrows = true;
583 else if (node->hashnulls)
585 (void) LookupTupleHashEntry(node->hashnulls, slot, &isnew);
586 node->havenullrows = true;
590 * Reset innerecontext after each inner tuple to free any memory used
591 * during ExecProject.
593 ResetExprContext(innerecontext);
597 * Since the projected tuples are in the sub-query's context and not the
598 * main context, we'd better clear the tuple slot before there's any
599 * chance of a reset of the sub-query's context. Else we will have the
600 * potential for a double free attempt. (XXX possibly no longer needed,
603 ExecClearTuple(node->projRight->pi_slot);
605 MemoryContextSwitchTo(oldcontext);
609 * findPartialMatch: does the hashtable contain an entry that is not
610 * provably distinct from the tuple?
612 * We have to scan the whole hashtable; we can't usefully use hashkeys
613 * to guide probing, since we might get partial matches on tuples with
614 * hashkeys quite unrelated to what we'd get from the given tuple.
616 * Caller must provide the equality functions to use, since in cross-type
617 * cases these are different from the hashtable's internal functions.
620 findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
621 FmgrInfo *eqfunctions)
623 int numCols = hashtable->numCols;
624 AttrNumber *keyColIdx = hashtable->keyColIdx;
625 TupleHashIterator hashiter;
626 TupleHashEntry entry;
628 InitTupleHashIterator(hashtable, &hashiter);
629 while ((entry = ScanTupleHashTable(&hashiter)) != NULL)
631 ExecStoreMinimalTuple(entry->firstTuple, hashtable->tableslot, false);
632 if (!execTuplesUnequal(slot, hashtable->tableslot,
637 TermTupleHashIterator(&hashiter);
641 /* No TermTupleHashIterator call needed here */
646 * slotAllNulls: is the slot completely NULL?
648 * This does not test for dropped columns, which is OK because we only
649 * use it on projected tuples.
652 slotAllNulls(TupleTableSlot *slot)
654 int ncols = slot->tts_tupleDescriptor->natts;
657 for (i = 1; i <= ncols; i++)
659 if (!slot_attisnull(slot, i))
666 * slotNoNulls: is the slot entirely not NULL?
668 * This does not test for dropped columns, which is OK because we only
669 * use it on projected tuples.
672 slotNoNulls(TupleTableSlot *slot)
674 int ncols = slot->tts_tupleDescriptor->natts;
677 for (i = 1; i <= ncols; i++)
679 if (slot_attisnull(slot, i))
685 /* ----------------------------------------------------------------
688 * Create a SubPlanState for a SubPlan; this is the SubPlan-specific part
689 * of ExecInitExpr(). We split it out so that it can be used for InitPlans
690 * as well as regular SubPlans. Note that we don't link the SubPlan into
691 * the parent's subPlan list, because that shouldn't happen for InitPlans.
692 * Instead, ExecInitExpr() does that one part.
693 * ----------------------------------------------------------------
696 ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
698 SubPlanState *sstate = makeNode(SubPlanState);
699 EState *estate = parent->state;
701 sstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecSubPlan;
702 sstate->xprstate.expr = (Expr *) subplan;
704 /* Link the SubPlanState to already-initialized subplan */
705 sstate->planstate = (PlanState *) list_nth(estate->es_subplanstates,
706 subplan->plan_id - 1);
708 /* ... and to its parent's state */
709 sstate->parent = parent;
711 /* Initialize subexpressions */
712 sstate->testexpr = ExecInitExpr((Expr *) subplan->testexpr, parent);
713 sstate->args = (List *) ExecInitExpr((Expr *) subplan->args, parent);
716 * initialize my state
718 sstate->curTuple = NULL;
719 sstate->curArray = PointerGetDatum(NULL);
720 sstate->projLeft = NULL;
721 sstate->projRight = NULL;
722 sstate->hashtable = NULL;
723 sstate->hashnulls = NULL;
724 sstate->hashtablecxt = NULL;
725 sstate->hashtempcxt = NULL;
726 sstate->innerecontext = NULL;
727 sstate->keyColIdx = NULL;
728 sstate->tab_hash_funcs = NULL;
729 sstate->tab_eq_funcs = NULL;
730 sstate->lhs_hash_funcs = NULL;
731 sstate->cur_eq_funcs = NULL;
734 * If this is an initplan or MULTIEXPR subplan, it has output parameters
735 * that the parent plan will use, so mark those parameters as needing
736 * evaluation. We don't actually run the subplan until we first need one
739 * A CTE subplan's output parameter is never to be evaluated in the normal
740 * way, so skip this in that case.
742 * Note that we don't set parent->chgParam here: the parent plan hasn't
743 * been run yet, so no need to force it to re-run.
745 if (subplan->setParam != NIL && subplan->subLinkType != CTE_SUBLINK)
749 foreach(lst, subplan->setParam)
751 int paramid = lfirst_int(lst);
752 ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
754 prm->execPlan = sstate;
759 * If we are going to hash the subquery output, initialize relevant stuff.
760 * (We don't create the hashtable until needed, though.)
762 if (subplan->useHashTable)
767 TupleTableSlot *slot;
775 /* We need a memory context to hold the hash table(s) */
776 sstate->hashtablecxt =
777 AllocSetContextCreate(CurrentMemoryContext,
778 "Subplan HashTable Context",
779 ALLOCSET_DEFAULT_MINSIZE,
780 ALLOCSET_DEFAULT_INITSIZE,
781 ALLOCSET_DEFAULT_MAXSIZE);
782 /* and a small one for the hash tables to use as temp storage */
783 sstate->hashtempcxt =
784 AllocSetContextCreate(CurrentMemoryContext,
785 "Subplan HashTable Temp Context",
786 ALLOCSET_SMALL_MINSIZE,
787 ALLOCSET_SMALL_INITSIZE,
788 ALLOCSET_SMALL_MAXSIZE);
789 /* and a short-lived exprcontext for function evaluation */
790 sstate->innerecontext = CreateExprContext(estate);
791 /* Silly little array of column numbers 1..n */
792 ncols = list_length(subplan->paramIds);
793 sstate->keyColIdx = (AttrNumber *) palloc(ncols * sizeof(AttrNumber));
794 for (i = 0; i < ncols; i++)
795 sstate->keyColIdx[i] = i + 1;
798 * We use ExecProject to evaluate the lefthand and righthand
799 * expression lists and form tuples. (You might think that we could
800 * use the sub-select's output tuples directly, but that is not the
801 * case if we had to insert any run-time coercions of the sub-select's
802 * output datatypes; anyway this avoids storing any resjunk columns
803 * that might be in the sub-select's output.) Run through the
804 * combining expressions to build tlists for the lefthand and
805 * righthand sides. We need both the ExprState list (for ExecProject)
806 * and the underlying parse Exprs (for ExecTypeFromTL).
808 * We also extract the combining operators themselves to initialize
809 * the equality and hashing functions for the hash tables.
811 if (IsA(sstate->testexpr->expr, OpExpr))
813 /* single combining operator */
814 oplist = list_make1(sstate->testexpr);
816 else if (and_clause((Node *) sstate->testexpr->expr))
818 /* multiple combining operators */
819 Assert(IsA(sstate->testexpr, BoolExprState));
820 oplist = ((BoolExprState *) sstate->testexpr)->args;
824 /* shouldn't see anything else in a hashable subplan */
825 elog(ERROR, "unrecognized testexpr type: %d",
826 (int) nodeTag(sstate->testexpr->expr));
827 oplist = NIL; /* keep compiler quiet */
829 Assert(list_length(oplist) == ncols);
831 lefttlist = righttlist = NIL;
832 leftptlist = rightptlist = NIL;
833 sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
834 sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
835 sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
836 sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
840 FuncExprState *fstate = (FuncExprState *) lfirst(l);
841 OpExpr *opexpr = (OpExpr *) fstate->xprstate.expr;
845 GenericExprState *tlestate;
850 Assert(IsA(fstate, FuncExprState));
851 Assert(IsA(opexpr, OpExpr));
852 Assert(list_length(fstate->args) == 2);
854 /* Process lefthand argument */
855 exstate = (ExprState *) linitial(fstate->args);
856 expr = exstate->expr;
857 tle = makeTargetEntry(expr,
861 tlestate = makeNode(GenericExprState);
862 tlestate->xprstate.expr = (Expr *) tle;
863 tlestate->xprstate.evalfunc = NULL;
864 tlestate->arg = exstate;
865 lefttlist = lappend(lefttlist, tlestate);
866 leftptlist = lappend(leftptlist, tle);
868 /* Process righthand argument */
869 exstate = (ExprState *) lsecond(fstate->args);
870 expr = exstate->expr;
871 tle = makeTargetEntry(expr,
875 tlestate = makeNode(GenericExprState);
876 tlestate->xprstate.expr = (Expr *) tle;
877 tlestate->xprstate.evalfunc = NULL;
878 tlestate->arg = exstate;
879 righttlist = lappend(righttlist, tlestate);
880 rightptlist = lappend(rightptlist, tle);
882 /* Lookup the equality function (potentially cross-type) */
883 fmgr_info(opexpr->opfuncid, &sstate->cur_eq_funcs[i - 1]);
884 fmgr_info_set_expr((Node *) opexpr, &sstate->cur_eq_funcs[i - 1]);
886 /* Look up the equality function for the RHS type */
887 if (!get_compatible_hash_operators(opexpr->opno,
889 elog(ERROR, "could not find compatible hash operator for operator %u",
891 fmgr_info(get_opcode(rhs_eq_oper), &sstate->tab_eq_funcs[i - 1]);
893 /* Lookup the associated hash functions */
894 if (!get_op_hash_functions(opexpr->opno,
895 &left_hashfn, &right_hashfn))
896 elog(ERROR, "could not find hash function for hash operator %u",
898 fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
899 fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
905 * Construct tupdescs, slots and projection nodes for left and right
906 * sides. The lefthand expressions will be evaluated in the parent
907 * plan node's exprcontext, which we don't have access to here.
908 * Fortunately we can just pass NULL for now and fill it in later
909 * (hack alert!). The righthand expressions will be evaluated in our
912 tupDesc = ExecTypeFromTL(leftptlist, false);
913 slot = ExecInitExtraTupleSlot(estate);
914 ExecSetSlotDescriptor(slot, tupDesc);
915 sstate->projLeft = ExecBuildProjectionInfo(lefttlist,
920 tupDesc = ExecTypeFromTL(rightptlist, false);
921 slot = ExecInitExtraTupleSlot(estate);
922 ExecSetSlotDescriptor(slot, tupDesc);
923 sstate->projRight = ExecBuildProjectionInfo(righttlist,
924 sstate->innerecontext,
932 /* ----------------------------------------------------------------
935 * Executes a subplan and sets its output parameters.
937 * This is called from ExecEvalParamExec() when the value of a PARAM_EXEC
938 * parameter is requested and the param's execPlan field is set (indicating
939 * that the param has not yet been evaluated). This allows lazy evaluation
940 * of initplans: we don't run the subplan until/unless we need its output.
941 * Note that this routine MUST clear the execPlan fields of the plan's
942 * output parameters after evaluating them!
943 * ----------------------------------------------------------------
946 ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
948 SubPlan *subplan = (SubPlan *) node->xprstate.expr;
949 PlanState *planstate = node->planstate;
950 SubLinkType subLinkType = subplan->subLinkType;
951 MemoryContext oldcontext;
952 TupleTableSlot *slot;
956 ArrayBuildStateAny *astate = NULL;
958 if (subLinkType == ANY_SUBLINK ||
959 subLinkType == ALL_SUBLINK)
960 elog(ERROR, "ANY/ALL subselect unsupported as initplan");
961 if (subLinkType == CTE_SUBLINK)
962 elog(ERROR, "CTE subplans should not be executed via ExecSetParamPlan");
964 /* Initialize ArrayBuildStateAny in caller's context, if needed */
965 if (subLinkType == ARRAY_SUBLINK)
966 astate = initArrayResultAny(subplan->firstColType,
967 CurrentMemoryContext);
970 * Must switch to per-query memory context.
972 oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
975 * Set Params of this plan from parent plan correlation values. (Any
976 * calculation we have to do is done in the parent econtext, since the
977 * Param values don't need to have per-query lifetime.) Currently, we
978 * expect only MULTIEXPR_SUBLINK plans to have any correlation values.
980 Assert(subplan->parParam == NIL || subLinkType == MULTIEXPR_SUBLINK);
981 Assert(list_length(subplan->parParam) == list_length(node->args));
983 forboth(l, subplan->parParam, pvar, node->args)
985 int paramid = lfirst_int(l);
986 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
988 prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar),
992 planstate->chgParam = bms_add_member(planstate->chgParam, paramid);
996 * Run the plan. (If it needs to be rescanned, the first ExecProcNode
997 * call will take care of that.)
999 for (slot = ExecProcNode(planstate);
1001 slot = ExecProcNode(planstate))
1003 TupleDesc tdesc = slot->tts_tupleDescriptor;
1006 if (subLinkType == EXISTS_SUBLINK)
1008 /* There can be only one setParam... */
1009 int paramid = linitial_int(subplan->setParam);
1010 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1012 prm->execPlan = NULL;
1013 prm->value = BoolGetDatum(true);
1014 prm->isnull = false;
1019 if (subLinkType == ARRAY_SUBLINK)
1025 /* stash away current value */
1026 Assert(subplan->firstColType == tdesc->attrs[0]->atttypid);
1027 dvalue = slot_getattr(slot, 1, &disnull);
1028 astate = accumArrayResultAny(astate, dvalue, disnull,
1029 subplan->firstColType, oldcontext);
1030 /* keep scanning subplan to collect all values */
1035 (subLinkType == EXPR_SUBLINK ||
1036 subLinkType == MULTIEXPR_SUBLINK ||
1037 subLinkType == ROWCOMPARE_SUBLINK))
1039 (errcode(ERRCODE_CARDINALITY_VIOLATION),
1040 errmsg("more than one row returned by a subquery used as an expression")));
1045 * We need to copy the subplan's tuple into our own context, in case
1046 * any of the params are pass-by-ref type --- the pointers stored in
1047 * the param structs will point at this copied tuple! node->curTuple
1048 * keeps track of the copied tuple for eventual freeing.
1051 heap_freetuple(node->curTuple);
1052 node->curTuple = ExecCopySlotTuple(slot);
1055 * Now set all the setParam params from the columns of the tuple
1057 foreach(l, subplan->setParam)
1059 int paramid = lfirst_int(l);
1060 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1062 prm->execPlan = NULL;
1063 prm->value = heap_getattr(node->curTuple, i, tdesc,
1069 if (subLinkType == ARRAY_SUBLINK)
1071 /* There can be only one setParam... */
1072 int paramid = linitial_int(subplan->setParam);
1073 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1076 * We build the result array in query context so it won't disappear;
1077 * to avoid leaking memory across repeated calls, we have to remember
1078 * the latest value, much as for curTuple above.
1080 if (node->curArray != PointerGetDatum(NULL))
1081 pfree(DatumGetPointer(node->curArray));
1082 node->curArray = makeArrayResultAny(astate,
1083 econtext->ecxt_per_query_memory,
1085 prm->execPlan = NULL;
1086 prm->value = node->curArray;
1087 prm->isnull = false;
1091 if (subLinkType == EXISTS_SUBLINK)
1093 /* There can be only one setParam... */
1094 int paramid = linitial_int(subplan->setParam);
1095 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1097 prm->execPlan = NULL;
1098 prm->value = BoolGetDatum(false);
1099 prm->isnull = false;
1103 /* For other sublink types, set all the output params to NULL */
1104 foreach(l, subplan->setParam)
1106 int paramid = lfirst_int(l);
1107 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1109 prm->execPlan = NULL;
1110 prm->value = (Datum) 0;
1116 MemoryContextSwitchTo(oldcontext);
1120 * Mark an initplan as needing recalculation
1123 ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent)
1125 PlanState *planstate = node->planstate;
1126 SubPlan *subplan = (SubPlan *) node->xprstate.expr;
1127 EState *estate = parent->state;
1131 if (subplan->parParam != NIL)
1132 elog(ERROR, "direct correlated subquery unsupported as initplan");
1133 if (subplan->setParam == NIL)
1134 elog(ERROR, "setParam list of initplan is empty");
1135 if (bms_is_empty(planstate->plan->extParam))
1136 elog(ERROR, "extParam set of initplan is empty");
1139 * Don't actually re-scan: it'll happen inside ExecSetParamPlan if needed.
1143 * Mark this subplan's output parameters as needing recalculation.
1145 * CTE subplans are never executed via parameter recalculation; instead
1146 * they get run when called by nodeCtescan.c. So don't mark the output
1147 * parameter of a CTE subplan as dirty, but do set the chgParam bit for it
1148 * so that dependent plan nodes will get told to rescan.
1150 foreach(l, subplan->setParam)
1152 int paramid = lfirst_int(l);
1153 ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
1155 if (subplan->subLinkType != CTE_SUBLINK)
1156 prm->execPlan = node;
1158 parent->chgParam = bms_add_member(parent->chgParam, paramid);
1164 * ExecInitAlternativeSubPlan
1166 * Initialize for execution of one of a set of alternative subplans.
1168 AlternativeSubPlanState *
1169 ExecInitAlternativeSubPlan(AlternativeSubPlan *asplan, PlanState *parent)
1171 AlternativeSubPlanState *asstate = makeNode(AlternativeSubPlanState);
1178 asstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecAlternativeSubPlan;
1179 asstate->xprstate.expr = (Expr *) asplan;
1182 * Initialize subplans. (Can we get away with only initializing the one
1183 * we're going to use?)
1185 asstate->subplans = (List *) ExecInitExpr((Expr *) asplan->subplans,
1189 * Select the one to be used. For this, we need an estimate of the number
1190 * of executions of the subplan. We use the number of output rows
1191 * expected from the parent plan node. This is a good estimate if we are
1192 * in the parent's targetlist, and an underestimate (but probably not by
1193 * more than a factor of 2) if we are in the qual.
1195 num_calls = parent->plan->plan_rows;
1198 * The planner saved enough info so that we don't have to work very hard
1199 * to estimate the total cost, given the number-of-calls estimate.
1201 Assert(list_length(asplan->subplans) == 2);
1202 subplan1 = (SubPlan *) linitial(asplan->subplans);
1203 subplan2 = (SubPlan *) lsecond(asplan->subplans);
1205 cost1 = subplan1->startup_cost + num_calls * subplan1->per_call_cost;
1206 cost2 = subplan2->startup_cost + num_calls * subplan2->per_call_cost;
1209 asstate->active = 0;
1211 asstate->active = 1;
1217 * ExecAlternativeSubPlan
1219 * Execute one of a set of alternative subplans.
1221 * Note: in future we might consider changing to different subplans on the
1222 * fly, in case the original rowcount estimate turns out to be way off.
1225 ExecAlternativeSubPlan(AlternativeSubPlanState *node,
1226 ExprContext *econtext,
1228 ExprDoneCond *isDone)
1230 /* Just pass control to the active subplan */
1231 SubPlanState *activesp = (SubPlanState *) list_nth(node->subplans,
1234 Assert(IsA(activesp, SubPlanState));
1236 return ExecSubPlan(activesp,