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) 1996-2018, 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 "miscadmin.h"
37 #include "optimizer/clauses.h"
38 #include "utils/array.h"
39 #include "utils/lsyscache.h"
40 #include "utils/memutils.h"
43 static Datum ExecHashSubPlan(SubPlanState *node,
44 ExprContext *econtext,
46 static Datum ExecScanSubPlan(SubPlanState *node,
47 ExprContext *econtext,
49 static void buildSubPlanHash(SubPlanState *node, ExprContext *econtext);
50 static bool findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
51 FmgrInfo *eqfunctions);
52 static bool slotAllNulls(TupleTableSlot *slot);
53 static bool slotNoNulls(TupleTableSlot *slot);
56 /* ----------------------------------------------------------------
59 * This is the main entry point for execution of a regular SubPlan.
60 * ----------------------------------------------------------------
63 ExecSubPlan(SubPlanState *node,
64 ExprContext *econtext,
67 SubPlan *subplan = node->subplan;
69 CHECK_FOR_INTERRUPTS();
71 /* Set non-null as default */
75 if (subplan->subLinkType == CTE_SUBLINK)
76 elog(ERROR, "CTE subplans should not be executed via ExecSubPlan");
77 if (subplan->setParam != NIL && subplan->subLinkType != MULTIEXPR_SUBLINK)
78 elog(ERROR, "cannot set parent params from subquery");
80 /* Select appropriate evaluation strategy */
81 if (subplan->useHashTable)
82 return ExecHashSubPlan(node, econtext, isNull);
84 return ExecScanSubPlan(node, econtext, isNull);
88 * ExecHashSubPlan: store subselect result in an in-memory hash table
91 ExecHashSubPlan(SubPlanState *node,
92 ExprContext *econtext,
95 SubPlan *subplan = node->subplan;
96 PlanState *planstate = node->planstate;
99 /* Shouldn't have any direct correlation Vars */
100 if (subplan->parParam != NIL || node->args != NIL)
101 elog(ERROR, "hashed subplan with direct correlation not supported");
104 * If first time through or we need to rescan the subplan, build the hash
107 if (node->hashtable == NULL || planstate->chgParam != NULL)
108 buildSubPlanHash(node, econtext);
111 * The result for an empty subplan is always FALSE; no need to evaluate
115 if (!node->havehashrows && !node->havenullrows)
116 return BoolGetDatum(false);
119 * Evaluate lefthand expressions and form a projection tuple. First we
120 * have to set the econtext to use (hack alert!).
122 node->projLeft->pi_exprContext = econtext;
123 slot = ExecProject(node->projLeft);
126 * Note: because we are typically called in a per-tuple context, we have
127 * to explicitly clear the projected tuple before returning. Otherwise,
128 * we'll have a double-free situation: the per-tuple context will probably
129 * be reset before we're called again, and then the tuple slot will think
130 * it still needs to free the tuple.
134 * If the LHS is all non-null, probe for an exact match in the main hash
135 * table. If we find one, the result is TRUE. Otherwise, scan the
136 * partly-null table to see if there are any rows that aren't provably
137 * unequal to the LHS; if so, the result is UNKNOWN. (We skip that part
138 * if we don't care about UNKNOWN.) Otherwise, the result is FALSE.
140 * Note: the reason we can avoid a full scan of the main hash table is
141 * that the combining operators are assumed never to yield NULL when both
142 * inputs are non-null. If they were to do so, we might need to produce
143 * UNKNOWN instead of FALSE because of an UNKNOWN result in comparing the
144 * LHS to some main-table entry --- which is a comparison we will not even
145 * make, unless there's a chance match of hash keys.
147 if (slotNoNulls(slot))
149 if (node->havehashrows &&
150 FindTupleHashEntry(node->hashtable,
153 node->lhs_hash_funcs) != NULL)
155 ExecClearTuple(slot);
156 return BoolGetDatum(true);
158 if (node->havenullrows &&
159 findPartialMatch(node->hashnulls, slot, node->cur_eq_funcs))
161 ExecClearTuple(slot);
163 return BoolGetDatum(false);
165 ExecClearTuple(slot);
166 return BoolGetDatum(false);
170 * When the LHS is partly or wholly NULL, we can never return TRUE. If we
171 * don't care about UNKNOWN, just return FALSE. Otherwise, if the LHS is
172 * wholly NULL, immediately return UNKNOWN. (Since the combining
173 * operators are strict, the result could only be FALSE if the sub-select
174 * were empty, but we already handled that case.) Otherwise, we must scan
175 * both the main and partly-null tables to see if there are any rows that
176 * aren't provably unequal to the LHS; if so, the result is UNKNOWN.
177 * Otherwise, the result is FALSE.
179 if (node->hashnulls == NULL)
181 ExecClearTuple(slot);
182 return BoolGetDatum(false);
184 if (slotAllNulls(slot))
186 ExecClearTuple(slot);
188 return BoolGetDatum(false);
190 /* Scan partly-null table first, since more likely to get a match */
191 if (node->havenullrows &&
192 findPartialMatch(node->hashnulls, slot, node->cur_eq_funcs))
194 ExecClearTuple(slot);
196 return BoolGetDatum(false);
198 if (node->havehashrows &&
199 findPartialMatch(node->hashtable, slot, node->cur_eq_funcs))
201 ExecClearTuple(slot);
203 return BoolGetDatum(false);
205 ExecClearTuple(slot);
206 return BoolGetDatum(false);
210 * ExecScanSubPlan: default case where we have to rescan subplan each time
213 ExecScanSubPlan(SubPlanState *node,
214 ExprContext *econtext,
217 SubPlan *subplan = node->subplan;
218 PlanState *planstate = node->planstate;
219 SubLinkType subLinkType = subplan->subLinkType;
220 MemoryContext oldcontext;
221 TupleTableSlot *slot;
223 bool found = false; /* true if got at least one subplan tuple */
226 ArrayBuildStateAny *astate = NULL;
229 * MULTIEXPR subplans, when "executed", just return NULL; but first we
230 * mark the subplan's output parameters as needing recalculation. (This
231 * is a bit of a hack: it relies on the subplan appearing later in its
232 * targetlist than any of the referencing Params, so that all the Params
233 * have been evaluated before we re-mark them for the next evaluation
234 * cycle. But in general resjunk tlist items appear after non-resjunk
235 * ones, so this should be safe.) Unlike ExecReScanSetParamPlan, we do
236 * *not* set bits in the parent plan node's chgParam, because we don't
237 * want to cause a rescan of the parent.
239 if (subLinkType == MULTIEXPR_SUBLINK)
241 EState *estate = node->parent->state;
243 foreach(l, subplan->setParam)
245 int paramid = lfirst_int(l);
246 ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
248 prm->execPlan = node;
254 /* Initialize ArrayBuildStateAny in caller's context, if needed */
255 if (subLinkType == ARRAY_SUBLINK)
256 astate = initArrayResultAny(subplan->firstColType,
257 CurrentMemoryContext, true);
260 * We are probably in a short-lived expression-evaluation context. Switch
261 * to the per-query context for manipulating the child plan's chgParam,
262 * calling ExecProcNode on it, etc.
264 oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
267 * Set Params of this plan from parent plan correlation values. (Any
268 * calculation we have to do is done in the parent econtext, since the
269 * Param values don't need to have per-query lifetime.)
271 Assert(list_length(subplan->parParam) == list_length(node->args));
273 forboth(l, subplan->parParam, pvar, node->args)
275 int paramid = lfirst_int(l);
276 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
278 prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar),
281 planstate->chgParam = bms_add_member(planstate->chgParam, paramid);
285 * Now that we've set up its parameters, we can reset the subplan.
287 ExecReScan(planstate);
290 * For all sublink types except EXPR_SUBLINK and ARRAY_SUBLINK, the result
291 * is boolean as are the results of the combining operators. We combine
292 * results across tuples (if the subplan produces more than one) using OR
293 * semantics for ANY_SUBLINK or AND semantics for ALL_SUBLINK.
294 * (ROWCOMPARE_SUBLINK doesn't allow multiple tuples from the subplan.)
295 * NULL results from the combining operators are handled according to the
296 * usual SQL semantics for OR and AND. The result for no input tuples is
297 * FALSE for ANY_SUBLINK, TRUE for ALL_SUBLINK, NULL for
298 * ROWCOMPARE_SUBLINK.
300 * For EXPR_SUBLINK we require the subplan to produce no more than one
301 * tuple, else an error is raised. If zero tuples are produced, we return
302 * NULL. Assuming we get a tuple, we just use its first column (there can
303 * be only one non-junk column in this case).
305 * For ARRAY_SUBLINK we allow the subplan to produce any number of tuples,
306 * and form an array of the first column's values. Note in particular
307 * that we produce a zero-element array if no tuples are produced (this is
308 * a change from pre-8.3 behavior of returning NULL).
310 result = BoolGetDatum(subLinkType == ALL_SUBLINK);
313 for (slot = ExecProcNode(planstate);
315 slot = ExecProcNode(planstate))
317 TupleDesc tdesc = slot->tts_tupleDescriptor;
323 if (subLinkType == EXISTS_SUBLINK)
326 result = BoolGetDatum(true);
330 if (subLinkType == EXPR_SUBLINK)
332 /* cannot allow multiple input tuples for EXPR sublink */
335 (errcode(ERRCODE_CARDINALITY_VIOLATION),
336 errmsg("more than one row returned by a subquery used as an expression")));
340 * We need to copy the subplan's tuple in case the result is of
341 * pass-by-ref type --- our return value will point into this
342 * copied tuple! Can't use the subplan's instance of the tuple
343 * since it won't still be valid after next ExecProcNode() call.
344 * node->curTuple keeps track of the copied tuple for eventual
348 heap_freetuple(node->curTuple);
349 node->curTuple = ExecCopySlotTuple(slot);
351 result = heap_getattr(node->curTuple, 1, tdesc, isNull);
352 /* keep scanning subplan to make sure there's only one tuple */
356 if (subLinkType == ARRAY_SUBLINK)
362 /* stash away current value */
363 Assert(subplan->firstColType == TupleDescAttr(tdesc, 0)->atttypid);
364 dvalue = slot_getattr(slot, 1, &disnull);
365 astate = accumArrayResultAny(astate, dvalue, disnull,
366 subplan->firstColType, oldcontext);
367 /* keep scanning subplan to collect all values */
371 /* cannot allow multiple input tuples for ROWCOMPARE sublink either */
372 if (subLinkType == ROWCOMPARE_SUBLINK && found)
374 (errcode(ERRCODE_CARDINALITY_VIOLATION),
375 errmsg("more than one row returned by a subquery used as an expression")));
380 * For ALL, ANY, and ROWCOMPARE sublinks, load up the Params
381 * representing the columns of the sub-select, and then evaluate the
382 * combining expression.
385 foreach(plst, subplan->paramIds)
387 int paramid = lfirst_int(plst);
388 ParamExecData *prmdata;
390 prmdata = &(econtext->ecxt_param_exec_vals[paramid]);
391 Assert(prmdata->execPlan == NULL);
392 prmdata->value = slot_getattr(slot, col, &(prmdata->isnull));
396 rowresult = ExecEvalExprSwitchContext(node->testexpr, econtext,
399 if (subLinkType == ANY_SUBLINK)
401 /* combine across rows per OR semantics */
404 else if (DatumGetBool(rowresult))
406 result = BoolGetDatum(true);
408 break; /* needn't look at any more rows */
411 else if (subLinkType == ALL_SUBLINK)
413 /* combine across rows per AND semantics */
416 else if (!DatumGetBool(rowresult))
418 result = BoolGetDatum(false);
420 break; /* needn't look at any more rows */
425 /* must be ROWCOMPARE_SUBLINK */
431 MemoryContextSwitchTo(oldcontext);
433 if (subLinkType == ARRAY_SUBLINK)
435 /* We return the result in the caller's context */
436 result = makeArrayResultAny(astate, oldcontext, true);
441 * deal with empty subplan result. result/isNull were previously
442 * initialized correctly for all sublink types except EXPR and
443 * ROWCOMPARE; for those, return NULL.
445 if (subLinkType == EXPR_SUBLINK ||
446 subLinkType == ROWCOMPARE_SUBLINK)
457 * buildSubPlanHash: load hash table by scanning subplan output.
460 buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
462 SubPlan *subplan = node->subplan;
463 PlanState *planstate = node->planstate;
464 int ncols = list_length(subplan->paramIds);
465 ExprContext *innerecontext = node->innerecontext;
466 MemoryContext oldcontext;
468 TupleTableSlot *slot;
470 Assert(subplan->subLinkType == ANY_SUBLINK);
473 * If we already had any hash tables, destroy 'em; then create empty hash
476 * If we need to distinguish accurately between FALSE and UNKNOWN (i.e.,
477 * NULL) results of the IN operation, then we have to store subplan output
478 * rows that are partly or wholly NULL. We store such rows in a separate
479 * hash table that we expect will be much smaller than the main table. (We
480 * can use hashing to eliminate partly-null rows that are not distinct. We
481 * keep them separate to minimize the cost of the inevitable full-table
482 * searches; see findPartialMatch.)
484 * If it's not necessary to distinguish FALSE and UNKNOWN, then we don't
485 * need to store subplan output rows that contain NULL.
487 MemoryContextReset(node->hashtablecxt);
488 node->hashtable = NULL;
489 node->hashnulls = NULL;
490 node->havehashrows = false;
491 node->havenullrows = false;
493 nbuckets = (long) Min(planstate->plan->plan_rows, (double) LONG_MAX);
497 node->hashtable = BuildTupleHashTable(ncols,
500 node->tab_hash_funcs,
507 if (!subplan->unknownEqFalse)
510 nbuckets = 1; /* there can only be one entry */
517 node->hashnulls = BuildTupleHashTable(ncols,
520 node->tab_hash_funcs,
529 * We are probably in a short-lived expression-evaluation context. Switch
530 * to the per-query context for manipulating the child plan.
532 oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
535 * Reset subplan to start.
537 ExecReScan(planstate);
540 * Scan the subplan and load the hash table(s). Note that when there are
541 * duplicate rows coming out of the sub-select, only one copy is stored.
543 for (slot = ExecProcNode(planstate);
545 slot = ExecProcNode(planstate))
552 * Load up the Params representing the raw sub-select outputs, then
553 * form the projection tuple to store in the hashtable.
555 foreach(plst, subplan->paramIds)
557 int paramid = lfirst_int(plst);
558 ParamExecData *prmdata;
560 prmdata = &(innerecontext->ecxt_param_exec_vals[paramid]);
561 Assert(prmdata->execPlan == NULL);
562 prmdata->value = slot_getattr(slot, col,
566 slot = ExecProject(node->projRight);
569 * If result contains any nulls, store separately or not at all.
571 if (slotNoNulls(slot))
573 (void) LookupTupleHashEntry(node->hashtable, slot, &isnew);
574 node->havehashrows = true;
576 else if (node->hashnulls)
578 (void) LookupTupleHashEntry(node->hashnulls, slot, &isnew);
579 node->havenullrows = true;
583 * Reset innerecontext after each inner tuple to free any memory used
584 * during ExecProject.
586 ResetExprContext(innerecontext);
590 * Since the projected tuples are in the sub-query's context and not the
591 * main context, we'd better clear the tuple slot before there's any
592 * chance of a reset of the sub-query's context. Else we will have the
593 * potential for a double free attempt. (XXX possibly no longer needed,
596 ExecClearTuple(node->projRight->pi_state.resultslot);
598 MemoryContextSwitchTo(oldcontext);
602 * findPartialMatch: does the hashtable contain an entry that is not
603 * provably distinct from the tuple?
605 * We have to scan the whole hashtable; we can't usefully use hashkeys
606 * to guide probing, since we might get partial matches on tuples with
607 * hashkeys quite unrelated to what we'd get from the given tuple.
609 * Caller must provide the equality functions to use, since in cross-type
610 * cases these are different from the hashtable's internal functions.
613 findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
614 FmgrInfo *eqfunctions)
616 int numCols = hashtable->numCols;
617 AttrNumber *keyColIdx = hashtable->keyColIdx;
618 TupleHashIterator hashiter;
619 TupleHashEntry entry;
621 InitTupleHashIterator(hashtable, &hashiter);
622 while ((entry = ScanTupleHashTable(hashtable, &hashiter)) != NULL)
624 CHECK_FOR_INTERRUPTS();
626 ExecStoreMinimalTuple(entry->firstTuple, hashtable->tableslot, false);
627 if (!execTuplesUnequal(slot, hashtable->tableslot,
632 TermTupleHashIterator(&hashiter);
636 /* No TermTupleHashIterator call needed here */
641 * slotAllNulls: is the slot completely NULL?
643 * This does not test for dropped columns, which is OK because we only
644 * use it on projected tuples.
647 slotAllNulls(TupleTableSlot *slot)
649 int ncols = slot->tts_tupleDescriptor->natts;
652 for (i = 1; i <= ncols; i++)
654 if (!slot_attisnull(slot, i))
661 * slotNoNulls: is the slot entirely not NULL?
663 * This does not test for dropped columns, which is OK because we only
664 * use it on projected tuples.
667 slotNoNulls(TupleTableSlot *slot)
669 int ncols = slot->tts_tupleDescriptor->natts;
672 for (i = 1; i <= ncols; i++)
674 if (slot_attisnull(slot, i))
680 /* ----------------------------------------------------------------
683 * Create a SubPlanState for a SubPlan; this is the SubPlan-specific part
684 * of ExecInitExpr(). We split it out so that it can be used for InitPlans
685 * as well as regular SubPlans. Note that we don't link the SubPlan into
686 * the parent's subPlan list, because that shouldn't happen for InitPlans.
687 * Instead, ExecInitExpr() does that one part.
688 * ----------------------------------------------------------------
691 ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
693 SubPlanState *sstate = makeNode(SubPlanState);
694 EState *estate = parent->state;
696 sstate->subplan = subplan;
698 /* Link the SubPlanState to already-initialized subplan */
699 sstate->planstate = (PlanState *) list_nth(estate->es_subplanstates,
700 subplan->plan_id - 1);
702 /* ... and to its parent's state */
703 sstate->parent = parent;
705 /* Initialize subexpressions */
706 sstate->testexpr = ExecInitExpr((Expr *) subplan->testexpr, parent);
707 sstate->args = ExecInitExprList(subplan->args, parent);
710 * initialize my state
712 sstate->curTuple = NULL;
713 sstate->curArray = PointerGetDatum(NULL);
714 sstate->projLeft = NULL;
715 sstate->projRight = NULL;
716 sstate->hashtable = NULL;
717 sstate->hashnulls = NULL;
718 sstate->hashtablecxt = NULL;
719 sstate->hashtempcxt = NULL;
720 sstate->innerecontext = NULL;
721 sstate->keyColIdx = NULL;
722 sstate->tab_hash_funcs = NULL;
723 sstate->tab_eq_funcs = NULL;
724 sstate->lhs_hash_funcs = NULL;
725 sstate->cur_eq_funcs = NULL;
728 * If this is an initplan or MULTIEXPR subplan, it has output parameters
729 * that the parent plan will use, so mark those parameters as needing
730 * evaluation. We don't actually run the subplan until we first need one
733 * A CTE subplan's output parameter is never to be evaluated in the normal
734 * way, so skip this in that case.
736 * Note that we don't set parent->chgParam here: the parent plan hasn't
737 * been run yet, so no need to force it to re-run.
739 if (subplan->setParam != NIL && subplan->subLinkType != CTE_SUBLINK)
743 foreach(lst, subplan->setParam)
745 int paramid = lfirst_int(lst);
746 ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
748 prm->execPlan = sstate;
753 * If we are going to hash the subquery output, initialize relevant stuff.
754 * (We don't create the hashtable until needed, though.)
756 if (subplan->useHashTable)
761 TupleTableSlot *slot;
767 /* We need a memory context to hold the hash table(s) */
768 sstate->hashtablecxt =
769 AllocSetContextCreate(CurrentMemoryContext,
770 "Subplan HashTable Context",
771 ALLOCSET_DEFAULT_SIZES);
772 /* and a small one for the hash tables to use as temp storage */
773 sstate->hashtempcxt =
774 AllocSetContextCreate(CurrentMemoryContext,
775 "Subplan HashTable Temp Context",
776 ALLOCSET_SMALL_SIZES);
777 /* and a short-lived exprcontext for function evaluation */
778 sstate->innerecontext = CreateExprContext(estate);
779 /* Silly little array of column numbers 1..n */
780 ncols = list_length(subplan->paramIds);
781 sstate->keyColIdx = (AttrNumber *) palloc(ncols * sizeof(AttrNumber));
782 for (i = 0; i < ncols; i++)
783 sstate->keyColIdx[i] = i + 1;
786 * We use ExecProject to evaluate the lefthand and righthand
787 * expression lists and form tuples. (You might think that we could
788 * use the sub-select's output tuples directly, but that is not the
789 * case if we had to insert any run-time coercions of the sub-select's
790 * output datatypes; anyway this avoids storing any resjunk columns
791 * that might be in the sub-select's output.) Run through the
792 * combining expressions to build tlists for the lefthand and
795 * We also extract the combining operators themselves to initialize
796 * the equality and hashing functions for the hash tables.
798 if (IsA(subplan->testexpr, OpExpr))
800 /* single combining operator */
801 oplist = list_make1(subplan->testexpr);
803 else if (and_clause((Node *) subplan->testexpr))
805 /* multiple combining operators */
806 oplist = castNode(BoolExpr, subplan->testexpr)->args;
810 /* shouldn't see anything else in a hashable subplan */
811 elog(ERROR, "unrecognized testexpr type: %d",
812 (int) nodeTag(subplan->testexpr));
813 oplist = NIL; /* keep compiler quiet */
815 Assert(list_length(oplist) == ncols);
817 lefttlist = righttlist = NIL;
818 sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
819 sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
820 sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
821 sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
825 OpExpr *opexpr = lfirst_node(OpExpr, l);
832 Assert(list_length(opexpr->args) == 2);
834 /* Process lefthand argument */
835 expr = (Expr *) linitial(opexpr->args);
836 tle = makeTargetEntry(expr,
840 lefttlist = lappend(lefttlist, tle);
842 /* Process righthand argument */
843 expr = (Expr *) lsecond(opexpr->args);
844 tle = makeTargetEntry(expr,
848 righttlist = lappend(righttlist, tle);
850 /* Lookup the equality function (potentially cross-type) */
851 fmgr_info(opexpr->opfuncid, &sstate->cur_eq_funcs[i - 1]);
852 fmgr_info_set_expr((Node *) opexpr, &sstate->cur_eq_funcs[i - 1]);
854 /* Look up the equality function for the RHS type */
855 if (!get_compatible_hash_operators(opexpr->opno,
857 elog(ERROR, "could not find compatible hash operator for operator %u",
859 fmgr_info(get_opcode(rhs_eq_oper), &sstate->tab_eq_funcs[i - 1]);
861 /* Lookup the associated hash functions */
862 if (!get_op_hash_functions(opexpr->opno,
863 &left_hashfn, &right_hashfn))
864 elog(ERROR, "could not find hash function for hash operator %u",
866 fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
867 fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
873 * Construct tupdescs, slots and projection nodes for left and right
874 * sides. The lefthand expressions will be evaluated in the parent
875 * plan node's exprcontext, which we don't have access to here.
876 * Fortunately we can just pass NULL for now and fill it in later
877 * (hack alert!). The righthand expressions will be evaluated in our
880 tupDesc = ExecTypeFromTL(lefttlist, false);
881 slot = ExecInitExtraTupleSlot(estate);
882 ExecSetSlotDescriptor(slot, tupDesc);
883 sstate->projLeft = ExecBuildProjectionInfo(lefttlist,
889 tupDesc = ExecTypeFromTL(righttlist, false);
890 slot = ExecInitExtraTupleSlot(estate);
891 ExecSetSlotDescriptor(slot, tupDesc);
892 sstate->projRight = ExecBuildProjectionInfo(righttlist,
893 sstate->innerecontext,
902 /* ----------------------------------------------------------------
905 * Executes a subplan and sets its output parameters.
907 * This is called from ExecEvalParamExec() when the value of a PARAM_EXEC
908 * parameter is requested and the param's execPlan field is set (indicating
909 * that the param has not yet been evaluated). This allows lazy evaluation
910 * of initplans: we don't run the subplan until/unless we need its output.
911 * Note that this routine MUST clear the execPlan fields of the plan's
912 * output parameters after evaluating them!
913 * ----------------------------------------------------------------
916 ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
918 SubPlan *subplan = node->subplan;
919 PlanState *planstate = node->planstate;
920 SubLinkType subLinkType = subplan->subLinkType;
921 MemoryContext oldcontext;
922 TupleTableSlot *slot;
926 ArrayBuildStateAny *astate = NULL;
928 if (subLinkType == ANY_SUBLINK ||
929 subLinkType == ALL_SUBLINK)
930 elog(ERROR, "ANY/ALL subselect unsupported as initplan");
931 if (subLinkType == CTE_SUBLINK)
932 elog(ERROR, "CTE subplans should not be executed via ExecSetParamPlan");
934 /* Initialize ArrayBuildStateAny in caller's context, if needed */
935 if (subLinkType == ARRAY_SUBLINK)
936 astate = initArrayResultAny(subplan->firstColType,
937 CurrentMemoryContext, true);
940 * Must switch to per-query memory context.
942 oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
945 * Set Params of this plan from parent plan correlation values. (Any
946 * calculation we have to do is done in the parent econtext, since the
947 * Param values don't need to have per-query lifetime.) Currently, we
948 * expect only MULTIEXPR_SUBLINK plans to have any correlation values.
950 Assert(subplan->parParam == NIL || subLinkType == MULTIEXPR_SUBLINK);
951 Assert(list_length(subplan->parParam) == list_length(node->args));
953 forboth(l, subplan->parParam, pvar, node->args)
955 int paramid = lfirst_int(l);
956 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
958 prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar),
961 planstate->chgParam = bms_add_member(planstate->chgParam, paramid);
965 * Run the plan. (If it needs to be rescanned, the first ExecProcNode
966 * call will take care of that.)
968 for (slot = ExecProcNode(planstate);
970 slot = ExecProcNode(planstate))
972 TupleDesc tdesc = slot->tts_tupleDescriptor;
975 if (subLinkType == EXISTS_SUBLINK)
977 /* There can be only one setParam... */
978 int paramid = linitial_int(subplan->setParam);
979 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
981 prm->execPlan = NULL;
982 prm->value = BoolGetDatum(true);
988 if (subLinkType == ARRAY_SUBLINK)
994 /* stash away current value */
995 Assert(subplan->firstColType == TupleDescAttr(tdesc, 0)->atttypid);
996 dvalue = slot_getattr(slot, 1, &disnull);
997 astate = accumArrayResultAny(astate, dvalue, disnull,
998 subplan->firstColType, oldcontext);
999 /* keep scanning subplan to collect all values */
1004 (subLinkType == EXPR_SUBLINK ||
1005 subLinkType == MULTIEXPR_SUBLINK ||
1006 subLinkType == ROWCOMPARE_SUBLINK))
1008 (errcode(ERRCODE_CARDINALITY_VIOLATION),
1009 errmsg("more than one row returned by a subquery used as an expression")));
1014 * We need to copy the subplan's tuple into our own context, in case
1015 * any of the params are pass-by-ref type --- the pointers stored in
1016 * the param structs will point at this copied tuple! node->curTuple
1017 * keeps track of the copied tuple for eventual freeing.
1020 heap_freetuple(node->curTuple);
1021 node->curTuple = ExecCopySlotTuple(slot);
1024 * Now set all the setParam params from the columns of the tuple
1026 foreach(l, subplan->setParam)
1028 int paramid = lfirst_int(l);
1029 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1031 prm->execPlan = NULL;
1032 prm->value = heap_getattr(node->curTuple, i, tdesc,
1038 if (subLinkType == ARRAY_SUBLINK)
1040 /* There can be only one setParam... */
1041 int paramid = linitial_int(subplan->setParam);
1042 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1045 * We build the result array in query context so it won't disappear;
1046 * to avoid leaking memory across repeated calls, we have to remember
1047 * the latest value, much as for curTuple above.
1049 if (node->curArray != PointerGetDatum(NULL))
1050 pfree(DatumGetPointer(node->curArray));
1051 node->curArray = makeArrayResultAny(astate,
1052 econtext->ecxt_per_query_memory,
1054 prm->execPlan = NULL;
1055 prm->value = node->curArray;
1056 prm->isnull = false;
1060 if (subLinkType == EXISTS_SUBLINK)
1062 /* There can be only one setParam... */
1063 int paramid = linitial_int(subplan->setParam);
1064 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1066 prm->execPlan = NULL;
1067 prm->value = BoolGetDatum(false);
1068 prm->isnull = false;
1072 /* For other sublink types, set all the output params to NULL */
1073 foreach(l, subplan->setParam)
1075 int paramid = lfirst_int(l);
1076 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1078 prm->execPlan = NULL;
1079 prm->value = (Datum) 0;
1085 MemoryContextSwitchTo(oldcontext);
1089 * Mark an initplan as needing recalculation
1092 ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent)
1094 PlanState *planstate = node->planstate;
1095 SubPlan *subplan = node->subplan;
1096 EState *estate = parent->state;
1100 if (subplan->parParam != NIL)
1101 elog(ERROR, "direct correlated subquery unsupported as initplan");
1102 if (subplan->setParam == NIL)
1103 elog(ERROR, "setParam list of initplan is empty");
1104 if (bms_is_empty(planstate->plan->extParam))
1105 elog(ERROR, "extParam set of initplan is empty");
1108 * Don't actually re-scan: it'll happen inside ExecSetParamPlan if needed.
1112 * Mark this subplan's output parameters as needing recalculation.
1114 * CTE subplans are never executed via parameter recalculation; instead
1115 * they get run when called by nodeCtescan.c. So don't mark the output
1116 * parameter of a CTE subplan as dirty, but do set the chgParam bit for it
1117 * so that dependent plan nodes will get told to rescan.
1119 foreach(l, subplan->setParam)
1121 int paramid = lfirst_int(l);
1122 ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
1124 if (subplan->subLinkType != CTE_SUBLINK)
1125 prm->execPlan = node;
1127 parent->chgParam = bms_add_member(parent->chgParam, paramid);
1133 * ExecInitAlternativeSubPlan
1135 * Initialize for execution of one of a set of alternative subplans.
1137 AlternativeSubPlanState *
1138 ExecInitAlternativeSubPlan(AlternativeSubPlan *asplan, PlanState *parent)
1140 AlternativeSubPlanState *asstate = makeNode(AlternativeSubPlanState);
1148 asstate->subplan = asplan;
1151 * Initialize subplans. (Can we get away with only initializing the one
1152 * we're going to use?)
1154 foreach(lc, asplan->subplans)
1156 SubPlan *sp = lfirst_node(SubPlan, lc);
1157 SubPlanState *sps = ExecInitSubPlan(sp, parent);
1159 asstate->subplans = lappend(asstate->subplans, sps);
1160 parent->subPlan = lappend(parent->subPlan, sps);
1164 * Select the one to be used. For this, we need an estimate of the number
1165 * of executions of the subplan. We use the number of output rows
1166 * expected from the parent plan node. This is a good estimate if we are
1167 * in the parent's targetlist, and an underestimate (but probably not by
1168 * more than a factor of 2) if we are in the qual.
1170 num_calls = parent->plan->plan_rows;
1173 * The planner saved enough info so that we don't have to work very hard
1174 * to estimate the total cost, given the number-of-calls estimate.
1176 Assert(list_length(asplan->subplans) == 2);
1177 subplan1 = (SubPlan *) linitial(asplan->subplans);
1178 subplan2 = (SubPlan *) lsecond(asplan->subplans);
1180 cost1 = subplan1->startup_cost + num_calls * subplan1->per_call_cost;
1181 cost2 = subplan2->startup_cost + num_calls * subplan2->per_call_cost;
1184 asstate->active = 0;
1186 asstate->active = 1;
1192 * ExecAlternativeSubPlan
1194 * Execute one of a set of alternative subplans.
1196 * Note: in future we might consider changing to different subplans on the
1197 * fly, in case the original rowcount estimate turns out to be way off.
1200 ExecAlternativeSubPlan(AlternativeSubPlanState *node,
1201 ExprContext *econtext,
1204 /* Just pass control to the active subplan */
1205 SubPlanState *activesp = list_nth_node(SubPlanState,
1206 node->subplans, node->active);
1208 return ExecSubPlan(activesp, econtext, isNull);