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) 1996-2016, 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, true);
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,
516 if (!subplan->unknownEqFalse)
519 nbuckets = 1; /* there can only be one entry */
526 node->hashnulls = BuildTupleHashTable(ncols,
529 node->tab_hash_funcs,
538 * We are probably in a short-lived expression-evaluation context. Switch
539 * to the per-query context for manipulating the child plan.
541 oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
544 * Reset subplan to start.
546 ExecReScan(planstate);
549 * Scan the subplan and load the hash table(s). Note that when there are
550 * duplicate rows coming out of the sub-select, only one copy is stored.
552 for (slot = ExecProcNode(planstate);
554 slot = ExecProcNode(planstate))
561 * Load up the Params representing the raw sub-select outputs, then
562 * form the projection tuple to store in the hashtable.
564 foreach(plst, subplan->paramIds)
566 int paramid = lfirst_int(plst);
567 ParamExecData *prmdata;
569 prmdata = &(innerecontext->ecxt_param_exec_vals[paramid]);
570 Assert(prmdata->execPlan == NULL);
571 prmdata->value = slot_getattr(slot, col,
575 slot = ExecProject(node->projRight, NULL);
578 * If result contains any nulls, store separately or not at all.
580 if (slotNoNulls(slot))
582 (void) LookupTupleHashEntry(node->hashtable, slot, &isnew);
583 node->havehashrows = true;
585 else if (node->hashnulls)
587 (void) LookupTupleHashEntry(node->hashnulls, slot, &isnew);
588 node->havenullrows = true;
592 * Reset innerecontext after each inner tuple to free any memory used
593 * during ExecProject.
595 ResetExprContext(innerecontext);
599 * Since the projected tuples are in the sub-query's context and not the
600 * main context, we'd better clear the tuple slot before there's any
601 * chance of a reset of the sub-query's context. Else we will have the
602 * potential for a double free attempt. (XXX possibly no longer needed,
605 ExecClearTuple(node->projRight->pi_slot);
607 MemoryContextSwitchTo(oldcontext);
611 * findPartialMatch: does the hashtable contain an entry that is not
612 * provably distinct from the tuple?
614 * We have to scan the whole hashtable; we can't usefully use hashkeys
615 * to guide probing, since we might get partial matches on tuples with
616 * hashkeys quite unrelated to what we'd get from the given tuple.
618 * Caller must provide the equality functions to use, since in cross-type
619 * cases these are different from the hashtable's internal functions.
622 findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
623 FmgrInfo *eqfunctions)
625 int numCols = hashtable->numCols;
626 AttrNumber *keyColIdx = hashtable->keyColIdx;
627 TupleHashIterator hashiter;
628 TupleHashEntry entry;
630 InitTupleHashIterator(hashtable, &hashiter);
631 while ((entry = ScanTupleHashTable(hashtable, &hashiter)) != NULL)
633 ExecStoreMinimalTuple(entry->firstTuple, hashtable->tableslot, false);
634 if (!execTuplesUnequal(slot, hashtable->tableslot,
639 TermTupleHashIterator(&hashiter);
643 /* No TermTupleHashIterator call needed here */
648 * slotAllNulls: is the slot completely NULL?
650 * This does not test for dropped columns, which is OK because we only
651 * use it on projected tuples.
654 slotAllNulls(TupleTableSlot *slot)
656 int ncols = slot->tts_tupleDescriptor->natts;
659 for (i = 1; i <= ncols; i++)
661 if (!slot_attisnull(slot, i))
668 * slotNoNulls: is the slot entirely not NULL?
670 * This does not test for dropped columns, which is OK because we only
671 * use it on projected tuples.
674 slotNoNulls(TupleTableSlot *slot)
676 int ncols = slot->tts_tupleDescriptor->natts;
679 for (i = 1; i <= ncols; i++)
681 if (slot_attisnull(slot, i))
687 /* ----------------------------------------------------------------
690 * Create a SubPlanState for a SubPlan; this is the SubPlan-specific part
691 * of ExecInitExpr(). We split it out so that it can be used for InitPlans
692 * as well as regular SubPlans. Note that we don't link the SubPlan into
693 * the parent's subPlan list, because that shouldn't happen for InitPlans.
694 * Instead, ExecInitExpr() does that one part.
695 * ----------------------------------------------------------------
698 ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
700 SubPlanState *sstate = makeNode(SubPlanState);
701 EState *estate = parent->state;
703 sstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecSubPlan;
704 sstate->xprstate.expr = (Expr *) subplan;
706 /* Link the SubPlanState to already-initialized subplan */
707 sstate->planstate = (PlanState *) list_nth(estate->es_subplanstates,
708 subplan->plan_id - 1);
710 /* ... and to its parent's state */
711 sstate->parent = parent;
713 /* Initialize subexpressions */
714 sstate->testexpr = ExecInitExpr((Expr *) subplan->testexpr, parent);
715 sstate->args = (List *) ExecInitExpr((Expr *) subplan->args, parent);
718 * initialize my state
720 sstate->curTuple = NULL;
721 sstate->curArray = PointerGetDatum(NULL);
722 sstate->projLeft = NULL;
723 sstate->projRight = NULL;
724 sstate->hashtable = NULL;
725 sstate->hashnulls = NULL;
726 sstate->hashtablecxt = NULL;
727 sstate->hashtempcxt = NULL;
728 sstate->innerecontext = NULL;
729 sstate->keyColIdx = NULL;
730 sstate->tab_hash_funcs = NULL;
731 sstate->tab_eq_funcs = NULL;
732 sstate->lhs_hash_funcs = NULL;
733 sstate->cur_eq_funcs = NULL;
736 * If this is an initplan or MULTIEXPR subplan, it has output parameters
737 * that the parent plan will use, so mark those parameters as needing
738 * evaluation. We don't actually run the subplan until we first need one
741 * A CTE subplan's output parameter is never to be evaluated in the normal
742 * way, so skip this in that case.
744 * Note that we don't set parent->chgParam here: the parent plan hasn't
745 * been run yet, so no need to force it to re-run.
747 if (subplan->setParam != NIL && subplan->subLinkType != CTE_SUBLINK)
751 foreach(lst, subplan->setParam)
753 int paramid = lfirst_int(lst);
754 ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
756 prm->execPlan = sstate;
761 * If we are going to hash the subquery output, initialize relevant stuff.
762 * (We don't create the hashtable until needed, though.)
764 if (subplan->useHashTable)
769 TupleTableSlot *slot;
777 /* We need a memory context to hold the hash table(s) */
778 sstate->hashtablecxt =
779 AllocSetContextCreate(CurrentMemoryContext,
780 "Subplan HashTable Context",
781 ALLOCSET_DEFAULT_SIZES);
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_SIZES);
787 /* and a short-lived exprcontext for function evaluation */
788 sstate->innerecontext = CreateExprContext(estate);
789 /* Silly little array of column numbers 1..n */
790 ncols = list_length(subplan->paramIds);
791 sstate->keyColIdx = (AttrNumber *) palloc(ncols * sizeof(AttrNumber));
792 for (i = 0; i < ncols; i++)
793 sstate->keyColIdx[i] = i + 1;
796 * We use ExecProject to evaluate the lefthand and righthand
797 * expression lists and form tuples. (You might think that we could
798 * use the sub-select's output tuples directly, but that is not the
799 * case if we had to insert any run-time coercions of the sub-select's
800 * output datatypes; anyway this avoids storing any resjunk columns
801 * that might be in the sub-select's output.) Run through the
802 * combining expressions to build tlists for the lefthand and
803 * righthand sides. We need both the ExprState list (for ExecProject)
804 * and the underlying parse Exprs (for ExecTypeFromTL).
806 * We also extract the combining operators themselves to initialize
807 * the equality and hashing functions for the hash tables.
809 if (IsA(sstate->testexpr->expr, OpExpr))
811 /* single combining operator */
812 oplist = list_make1(sstate->testexpr);
814 else if (and_clause((Node *) sstate->testexpr->expr))
816 /* multiple combining operators */
817 Assert(IsA(sstate->testexpr, BoolExprState));
818 oplist = ((BoolExprState *) sstate->testexpr)->args;
822 /* shouldn't see anything else in a hashable subplan */
823 elog(ERROR, "unrecognized testexpr type: %d",
824 (int) nodeTag(sstate->testexpr->expr));
825 oplist = NIL; /* keep compiler quiet */
827 Assert(list_length(oplist) == ncols);
829 lefttlist = righttlist = NIL;
830 leftptlist = rightptlist = NIL;
831 sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
832 sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
833 sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
834 sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
838 FuncExprState *fstate = (FuncExprState *) lfirst(l);
839 OpExpr *opexpr = (OpExpr *) fstate->xprstate.expr;
843 GenericExprState *tlestate;
848 Assert(IsA(fstate, FuncExprState));
849 Assert(IsA(opexpr, OpExpr));
850 Assert(list_length(fstate->args) == 2);
852 /* Process lefthand argument */
853 exstate = (ExprState *) linitial(fstate->args);
854 expr = exstate->expr;
855 tle = makeTargetEntry(expr,
859 tlestate = makeNode(GenericExprState);
860 tlestate->xprstate.expr = (Expr *) tle;
861 tlestate->xprstate.evalfunc = NULL;
862 tlestate->arg = exstate;
863 lefttlist = lappend(lefttlist, tlestate);
864 leftptlist = lappend(leftptlist, tle);
866 /* Process righthand argument */
867 exstate = (ExprState *) lsecond(fstate->args);
868 expr = exstate->expr;
869 tle = makeTargetEntry(expr,
873 tlestate = makeNode(GenericExprState);
874 tlestate->xprstate.expr = (Expr *) tle;
875 tlestate->xprstate.evalfunc = NULL;
876 tlestate->arg = exstate;
877 righttlist = lappend(righttlist, tlestate);
878 rightptlist = lappend(rightptlist, tle);
880 /* Lookup the equality function (potentially cross-type) */
881 fmgr_info(opexpr->opfuncid, &sstate->cur_eq_funcs[i - 1]);
882 fmgr_info_set_expr((Node *) opexpr, &sstate->cur_eq_funcs[i - 1]);
884 /* Look up the equality function for the RHS type */
885 if (!get_compatible_hash_operators(opexpr->opno,
887 elog(ERROR, "could not find compatible hash operator for operator %u",
889 fmgr_info(get_opcode(rhs_eq_oper), &sstate->tab_eq_funcs[i - 1]);
891 /* Lookup the associated hash functions */
892 if (!get_op_hash_functions(opexpr->opno,
893 &left_hashfn, &right_hashfn))
894 elog(ERROR, "could not find hash function for hash operator %u",
896 fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
897 fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
903 * Construct tupdescs, slots and projection nodes for left and right
904 * sides. The lefthand expressions will be evaluated in the parent
905 * plan node's exprcontext, which we don't have access to here.
906 * Fortunately we can just pass NULL for now and fill it in later
907 * (hack alert!). The righthand expressions will be evaluated in our
910 tupDesc = ExecTypeFromTL(leftptlist, false);
911 slot = ExecInitExtraTupleSlot(estate);
912 ExecSetSlotDescriptor(slot, tupDesc);
913 sstate->projLeft = ExecBuildProjectionInfo(lefttlist,
918 tupDesc = ExecTypeFromTL(rightptlist, false);
919 slot = ExecInitExtraTupleSlot(estate);
920 ExecSetSlotDescriptor(slot, tupDesc);
921 sstate->projRight = ExecBuildProjectionInfo(righttlist,
922 sstate->innerecontext,
930 /* ----------------------------------------------------------------
933 * Executes a subplan and sets its output parameters.
935 * This is called from ExecEvalParamExec() when the value of a PARAM_EXEC
936 * parameter is requested and the param's execPlan field is set (indicating
937 * that the param has not yet been evaluated). This allows lazy evaluation
938 * of initplans: we don't run the subplan until/unless we need its output.
939 * Note that this routine MUST clear the execPlan fields of the plan's
940 * output parameters after evaluating them!
941 * ----------------------------------------------------------------
944 ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
946 SubPlan *subplan = (SubPlan *) node->xprstate.expr;
947 PlanState *planstate = node->planstate;
948 SubLinkType subLinkType = subplan->subLinkType;
949 MemoryContext oldcontext;
950 TupleTableSlot *slot;
954 ArrayBuildStateAny *astate = NULL;
956 if (subLinkType == ANY_SUBLINK ||
957 subLinkType == ALL_SUBLINK)
958 elog(ERROR, "ANY/ALL subselect unsupported as initplan");
959 if (subLinkType == CTE_SUBLINK)
960 elog(ERROR, "CTE subplans should not be executed via ExecSetParamPlan");
962 /* Initialize ArrayBuildStateAny in caller's context, if needed */
963 if (subLinkType == ARRAY_SUBLINK)
964 astate = initArrayResultAny(subplan->firstColType,
965 CurrentMemoryContext, true);
968 * Must switch to per-query memory context.
970 oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
973 * Set Params of this plan from parent plan correlation values. (Any
974 * calculation we have to do is done in the parent econtext, since the
975 * Param values don't need to have per-query lifetime.) Currently, we
976 * expect only MULTIEXPR_SUBLINK plans to have any correlation values.
978 Assert(subplan->parParam == NIL || subLinkType == MULTIEXPR_SUBLINK);
979 Assert(list_length(subplan->parParam) == list_length(node->args));
981 forboth(l, subplan->parParam, pvar, node->args)
983 int paramid = lfirst_int(l);
984 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
986 prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar),
990 planstate->chgParam = bms_add_member(planstate->chgParam, paramid);
994 * Run the plan. (If it needs to be rescanned, the first ExecProcNode
995 * call will take care of that.)
997 for (slot = ExecProcNode(planstate);
999 slot = ExecProcNode(planstate))
1001 TupleDesc tdesc = slot->tts_tupleDescriptor;
1004 if (subLinkType == EXISTS_SUBLINK)
1006 /* There can be only one setParam... */
1007 int paramid = linitial_int(subplan->setParam);
1008 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1010 prm->execPlan = NULL;
1011 prm->value = BoolGetDatum(true);
1012 prm->isnull = false;
1017 if (subLinkType == ARRAY_SUBLINK)
1023 /* stash away current value */
1024 Assert(subplan->firstColType == tdesc->attrs[0]->atttypid);
1025 dvalue = slot_getattr(slot, 1, &disnull);
1026 astate = accumArrayResultAny(astate, dvalue, disnull,
1027 subplan->firstColType, oldcontext);
1028 /* keep scanning subplan to collect all values */
1033 (subLinkType == EXPR_SUBLINK ||
1034 subLinkType == MULTIEXPR_SUBLINK ||
1035 subLinkType == ROWCOMPARE_SUBLINK))
1037 (errcode(ERRCODE_CARDINALITY_VIOLATION),
1038 errmsg("more than one row returned by a subquery used as an expression")));
1043 * We need to copy the subplan's tuple into our own context, in case
1044 * any of the params are pass-by-ref type --- the pointers stored in
1045 * the param structs will point at this copied tuple! node->curTuple
1046 * keeps track of the copied tuple for eventual freeing.
1049 heap_freetuple(node->curTuple);
1050 node->curTuple = ExecCopySlotTuple(slot);
1053 * Now set all the setParam params from the columns of the tuple
1055 foreach(l, subplan->setParam)
1057 int paramid = lfirst_int(l);
1058 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1060 prm->execPlan = NULL;
1061 prm->value = heap_getattr(node->curTuple, i, tdesc,
1067 if (subLinkType == ARRAY_SUBLINK)
1069 /* There can be only one setParam... */
1070 int paramid = linitial_int(subplan->setParam);
1071 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1074 * We build the result array in query context so it won't disappear;
1075 * to avoid leaking memory across repeated calls, we have to remember
1076 * the latest value, much as for curTuple above.
1078 if (node->curArray != PointerGetDatum(NULL))
1079 pfree(DatumGetPointer(node->curArray));
1080 node->curArray = makeArrayResultAny(astate,
1081 econtext->ecxt_per_query_memory,
1083 prm->execPlan = NULL;
1084 prm->value = node->curArray;
1085 prm->isnull = false;
1089 if (subLinkType == EXISTS_SUBLINK)
1091 /* There can be only one setParam... */
1092 int paramid = linitial_int(subplan->setParam);
1093 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1095 prm->execPlan = NULL;
1096 prm->value = BoolGetDatum(false);
1097 prm->isnull = false;
1101 /* For other sublink types, set all the output params to NULL */
1102 foreach(l, subplan->setParam)
1104 int paramid = lfirst_int(l);
1105 ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1107 prm->execPlan = NULL;
1108 prm->value = (Datum) 0;
1114 MemoryContextSwitchTo(oldcontext);
1118 * Mark an initplan as needing recalculation
1121 ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent)
1123 PlanState *planstate = node->planstate;
1124 SubPlan *subplan = (SubPlan *) node->xprstate.expr;
1125 EState *estate = parent->state;
1129 if (subplan->parParam != NIL)
1130 elog(ERROR, "direct correlated subquery unsupported as initplan");
1131 if (subplan->setParam == NIL)
1132 elog(ERROR, "setParam list of initplan is empty");
1133 if (bms_is_empty(planstate->plan->extParam))
1134 elog(ERROR, "extParam set of initplan is empty");
1137 * Don't actually re-scan: it'll happen inside ExecSetParamPlan if needed.
1141 * Mark this subplan's output parameters as needing recalculation.
1143 * CTE subplans are never executed via parameter recalculation; instead
1144 * they get run when called by nodeCtescan.c. So don't mark the output
1145 * parameter of a CTE subplan as dirty, but do set the chgParam bit for it
1146 * so that dependent plan nodes will get told to rescan.
1148 foreach(l, subplan->setParam)
1150 int paramid = lfirst_int(l);
1151 ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
1153 if (subplan->subLinkType != CTE_SUBLINK)
1154 prm->execPlan = node;
1156 parent->chgParam = bms_add_member(parent->chgParam, paramid);
1162 * ExecInitAlternativeSubPlan
1164 * Initialize for execution of one of a set of alternative subplans.
1166 AlternativeSubPlanState *
1167 ExecInitAlternativeSubPlan(AlternativeSubPlan *asplan, PlanState *parent)
1169 AlternativeSubPlanState *asstate = makeNode(AlternativeSubPlanState);
1176 asstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecAlternativeSubPlan;
1177 asstate->xprstate.expr = (Expr *) asplan;
1180 * Initialize subplans. (Can we get away with only initializing the one
1181 * we're going to use?)
1183 asstate->subplans = (List *) ExecInitExpr((Expr *) asplan->subplans,
1187 * Select the one to be used. For this, we need an estimate of the number
1188 * of executions of the subplan. We use the number of output rows
1189 * expected from the parent plan node. This is a good estimate if we are
1190 * in the parent's targetlist, and an underestimate (but probably not by
1191 * more than a factor of 2) if we are in the qual.
1193 num_calls = parent->plan->plan_rows;
1196 * The planner saved enough info so that we don't have to work very hard
1197 * to estimate the total cost, given the number-of-calls estimate.
1199 Assert(list_length(asplan->subplans) == 2);
1200 subplan1 = (SubPlan *) linitial(asplan->subplans);
1201 subplan2 = (SubPlan *) lsecond(asplan->subplans);
1203 cost1 = subplan1->startup_cost + num_calls * subplan1->per_call_cost;
1204 cost2 = subplan2->startup_cost + num_calls * subplan2->per_call_cost;
1207 asstate->active = 0;
1209 asstate->active = 1;
1215 * ExecAlternativeSubPlan
1217 * Execute one of a set of alternative subplans.
1219 * Note: in future we might consider changing to different subplans on the
1220 * fly, in case the original rowcount estimate turns out to be way off.
1223 ExecAlternativeSubPlan(AlternativeSubPlanState *node,
1224 ExprContext *econtext,
1226 ExprDoneCond *isDone)
1228 /* Just pass control to the active subplan */
1229 SubPlanState *activesp = (SubPlanState *) list_nth(node->subplans,
1232 Assert(IsA(activesp, SubPlanState));
1234 return ExecSubPlan(activesp,