1
/*-------------------------------------------------------------------------
4
* routines to support subselects
6
* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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* src/backend/executor/nodeSubplan.c
12
*-------------------------------------------------------------------------
16
* ExecSubPlan - process a subselect
17
* ExecInitSubPlan - initialize a subselect
23
#include "executor/executor.h"
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#include "executor/nodeSubplan.h"
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#include "nodes/makefuncs.h"
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#include "optimizer/clauses.h"
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#include "utils/array.h"
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#include "utils/lsyscache.h"
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#include "utils/memutils.h"
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static Datum ExecSubPlan(SubPlanState *node,
33
ExprContext *econtext,
35
ExprDoneCond *isDone);
36
static Datum ExecAlternativeSubPlan(AlternativeSubPlanState *node,
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ExprContext *econtext,
39
ExprDoneCond *isDone);
40
static Datum ExecHashSubPlan(SubPlanState *node,
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ExprContext *econtext,
43
static Datum ExecScanSubPlan(SubPlanState *node,
44
ExprContext *econtext,
46
static void buildSubPlanHash(SubPlanState *node, ExprContext *econtext);
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static bool findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot);
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static bool slotAllNulls(TupleTableSlot *slot);
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static bool slotNoNulls(TupleTableSlot *slot);
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/* ----------------------------------------------------------------
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* ----------------------------------------------------------------
57
ExecSubPlan(SubPlanState *node,
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ExprContext *econtext,
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SubPlan *subplan = (SubPlan *) node->xprstate.expr;
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/* Set default values for result flags: non-null, not a set result */
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*isDone = ExprSingleResult;
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if (subplan->subLinkType == CTE_SUBLINK)
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elog(ERROR, "CTE subplans should not be executed via ExecSubPlan");
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if (subplan->setParam != NIL)
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elog(ERROR, "cannot set parent params from subquery");
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/* Select appropriate evaluation strategy */
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if (subplan->useHashTable)
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return ExecHashSubPlan(node, econtext, isNull);
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return ExecScanSubPlan(node, econtext, isNull);
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* ExecHashSubPlan: store subselect result in an in-memory hash table
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ExecHashSubPlan(SubPlanState *node,
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ExprContext *econtext,
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SubPlan *subplan = (SubPlan *) node->xprstate.expr;
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PlanState *planstate = node->planstate;
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/* Shouldn't have any direct correlation Vars */
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if (subplan->parParam != NIL || node->args != NIL)
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elog(ERROR, "hashed subplan with direct correlation not supported");
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* If first time through or we need to rescan the subplan, build the hash
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if (node->hashtable == NULL || planstate->chgParam != NULL)
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buildSubPlanHash(node, econtext);
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* The result for an empty subplan is always FALSE; no need to evaluate
110
if (!node->havehashrows && !node->havenullrows)
111
return BoolGetDatum(false);
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* Evaluate lefthand expressions and form a projection tuple. First we
115
* have to set the econtext to use (hack alert!).
117
node->projLeft->pi_exprContext = econtext;
118
slot = ExecProject(node->projLeft, NULL);
121
* Note: because we are typically called in a per-tuple context, we have
122
* to explicitly clear the projected tuple before returning. Otherwise,
123
* we'll have a double-free situation: the per-tuple context will probably
124
* be reset before we're called again, and then the tuple slot will think
125
* it still needs to free the tuple.
129
* If the LHS is all non-null, probe for an exact match in the main hash
130
* table. If we find one, the result is TRUE. Otherwise, scan the
131
* partly-null table to see if there are any rows that aren't provably
132
* unequal to the LHS; if so, the result is UNKNOWN. (We skip that part
133
* if we don't care about UNKNOWN.) Otherwise, the result is FALSE.
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* Note: the reason we can avoid a full scan of the main hash table is
136
* that the combining operators are assumed never to yield NULL when both
137
* inputs are non-null. If they were to do so, we might need to produce
138
* UNKNOWN instead of FALSE because of an UNKNOWN result in comparing the
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* LHS to some main-table entry --- which is a comparison we will not even
140
* make, unless there's a chance match of hash keys.
142
if (slotNoNulls(slot))
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if (node->havehashrows &&
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FindTupleHashEntry(node->hashtable,
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node->lhs_hash_funcs) != NULL)
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ExecClearTuple(slot);
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return BoolGetDatum(true);
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if (node->havenullrows &&
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findPartialMatch(node->hashnulls, slot))
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ExecClearTuple(slot);
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return BoolGetDatum(false);
160
ExecClearTuple(slot);
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return BoolGetDatum(false);
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* When the LHS is partly or wholly NULL, we can never return TRUE. If we
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* don't care about UNKNOWN, just return FALSE. Otherwise, if the LHS is
167
* wholly NULL, immediately return UNKNOWN. (Since the combining
168
* operators are strict, the result could only be FALSE if the sub-select
169
* were empty, but we already handled that case.) Otherwise, we must scan
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* both the main and partly-null tables to see if there are any rows that
171
* aren't provably unequal to the LHS; if so, the result is UNKNOWN.
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* Otherwise, the result is FALSE.
174
if (node->hashnulls == NULL)
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ExecClearTuple(slot);
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return BoolGetDatum(false);
179
if (slotAllNulls(slot))
181
ExecClearTuple(slot);
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return BoolGetDatum(false);
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/* Scan partly-null table first, since more likely to get a match */
186
if (node->havenullrows &&
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findPartialMatch(node->hashnulls, slot))
189
ExecClearTuple(slot);
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return BoolGetDatum(false);
193
if (node->havehashrows &&
194
findPartialMatch(node->hashtable, slot))
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ExecClearTuple(slot);
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return BoolGetDatum(false);
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ExecClearTuple(slot);
201
return BoolGetDatum(false);
205
* ExecScanSubPlan: default case where we have to rescan subplan each time
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ExecScanSubPlan(SubPlanState *node,
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ExprContext *econtext,
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SubPlan *subplan = (SubPlan *) node->xprstate.expr;
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PlanState *planstate = node->planstate;
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SubLinkType subLinkType = subplan->subLinkType;
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MemoryContext oldcontext;
216
TupleTableSlot *slot;
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bool found = false; /* TRUE if got at least one subplan tuple */
221
ArrayBuildState *astate = NULL;
224
* We are probably in a short-lived expression-evaluation context. Switch
225
* to the per-query context for manipulating the child plan's chgParam,
226
* calling ExecProcNode on it, etc.
228
oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
231
* Set Params of this plan from parent plan correlation values. (Any
232
* calculation we have to do is done in the parent econtext, since the
233
* Param values don't need to have per-query lifetime.)
235
Assert(list_length(subplan->parParam) == list_length(node->args));
237
forboth(l, subplan->parParam, pvar, node->args)
239
int paramid = lfirst_int(l);
240
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
242
prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar),
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planstate->chgParam = bms_add_member(planstate->chgParam, paramid);
250
* Now that we've set up its parameters, we can reset the subplan.
252
ExecReScan(planstate);
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* For all sublink types except EXPR_SUBLINK and ARRAY_SUBLINK, the result
256
* is boolean as are the results of the combining operators. We combine
257
* results across tuples (if the subplan produces more than one) using OR
258
* semantics for ANY_SUBLINK or AND semantics for ALL_SUBLINK.
259
* (ROWCOMPARE_SUBLINK doesn't allow multiple tuples from the subplan.)
260
* NULL results from the combining operators are handled according to the
261
* usual SQL semantics for OR and AND. The result for no input tuples is
262
* FALSE for ANY_SUBLINK, TRUE for ALL_SUBLINK, NULL for
263
* ROWCOMPARE_SUBLINK.
265
* For EXPR_SUBLINK we require the subplan to produce no more than one
266
* tuple, else an error is raised. If zero tuples are produced, we return
267
* NULL. Assuming we get a tuple, we just use its first column (there can
268
* be only one non-junk column in this case).
270
* For ARRAY_SUBLINK we allow the subplan to produce any number of tuples,
271
* and form an array of the first column's values. Note in particular
272
* that we produce a zero-element array if no tuples are produced (this is
273
* a change from pre-8.3 behavior of returning NULL).
275
result = BoolGetDatum(subLinkType == ALL_SUBLINK);
278
for (slot = ExecProcNode(planstate);
280
slot = ExecProcNode(planstate))
282
TupleDesc tdesc = slot->tts_tupleDescriptor;
288
if (subLinkType == EXISTS_SUBLINK)
291
result = BoolGetDatum(true);
295
if (subLinkType == EXPR_SUBLINK)
297
/* cannot allow multiple input tuples for EXPR sublink */
300
(errcode(ERRCODE_CARDINALITY_VIOLATION),
301
errmsg("more than one row returned by a subquery used as an expression")));
305
* We need to copy the subplan's tuple in case the result is of
306
* pass-by-ref type --- our return value will point into this
307
* copied tuple! Can't use the subplan's instance of the tuple
308
* since it won't still be valid after next ExecProcNode() call.
309
* node->curTuple keeps track of the copied tuple for eventual
313
heap_freetuple(node->curTuple);
314
node->curTuple = ExecCopySlotTuple(slot);
316
result = heap_getattr(node->curTuple, 1, tdesc, isNull);
317
/* keep scanning subplan to make sure there's only one tuple */
321
if (subLinkType == ARRAY_SUBLINK)
327
/* stash away current value */
328
Assert(subplan->firstColType == tdesc->attrs[0]->atttypid);
329
dvalue = slot_getattr(slot, 1, &disnull);
330
astate = accumArrayResult(astate, dvalue, disnull,
331
subplan->firstColType, oldcontext);
332
/* keep scanning subplan to collect all values */
336
/* cannot allow multiple input tuples for ROWCOMPARE sublink either */
337
if (subLinkType == ROWCOMPARE_SUBLINK && found)
339
(errcode(ERRCODE_CARDINALITY_VIOLATION),
340
errmsg("more than one row returned by a subquery used as an expression")));
345
* For ALL, ANY, and ROWCOMPARE sublinks, load up the Params
346
* representing the columns of the sub-select, and then evaluate the
347
* combining expression.
350
foreach(plst, subplan->paramIds)
352
int paramid = lfirst_int(plst);
353
ParamExecData *prmdata;
355
prmdata = &(econtext->ecxt_param_exec_vals[paramid]);
356
Assert(prmdata->execPlan == NULL);
357
prmdata->value = slot_getattr(slot, col, &(prmdata->isnull));
361
rowresult = ExecEvalExprSwitchContext(node->testexpr, econtext,
364
if (subLinkType == ANY_SUBLINK)
366
/* combine across rows per OR semantics */
369
else if (DatumGetBool(rowresult))
371
result = BoolGetDatum(true);
373
break; /* needn't look at any more rows */
376
else if (subLinkType == ALL_SUBLINK)
378
/* combine across rows per AND semantics */
381
else if (!DatumGetBool(rowresult))
383
result = BoolGetDatum(false);
385
break; /* needn't look at any more rows */
390
/* must be ROWCOMPARE_SUBLINK */
396
MemoryContextSwitchTo(oldcontext);
398
if (subLinkType == ARRAY_SUBLINK)
400
/* We return the result in the caller's context */
402
result = makeArrayResult(astate, oldcontext);
404
result = PointerGetDatum(construct_empty_array(subplan->firstColType));
409
* deal with empty subplan result. result/isNull were previously
410
* initialized correctly for all sublink types except EXPR and
411
* ROWCOMPARE; for those, return NULL.
413
if (subLinkType == EXPR_SUBLINK ||
414
subLinkType == ROWCOMPARE_SUBLINK)
425
* buildSubPlanHash: load hash table by scanning subplan output.
428
buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
430
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
431
PlanState *planstate = node->planstate;
432
int ncols = list_length(subplan->paramIds);
433
ExprContext *innerecontext = node->innerecontext;
434
MemoryContext oldcontext;
436
TupleTableSlot *slot;
438
Assert(subplan->subLinkType == ANY_SUBLINK);
441
* If we already had any hash tables, destroy 'em; then create empty hash
444
* If we need to distinguish accurately between FALSE and UNKNOWN (i.e.,
445
* NULL) results of the IN operation, then we have to store subplan output
446
* rows that are partly or wholly NULL. We store such rows in a separate
447
* hash table that we expect will be much smaller than the main table. (We
448
* can use hashing to eliminate partly-null rows that are not distinct. We
449
* keep them separate to minimize the cost of the inevitable full-table
450
* searches; see findPartialMatch.)
452
* If it's not necessary to distinguish FALSE and UNKNOWN, then we don't
453
* need to store subplan output rows that contain NULL.
455
MemoryContextReset(node->hashtablecxt);
456
node->hashtable = NULL;
457
node->hashnulls = NULL;
458
node->havehashrows = false;
459
node->havenullrows = false;
461
nbuckets = (int) ceil(planstate->plan->plan_rows);
465
node->hashtable = BuildTupleHashTable(ncols,
468
node->tab_hash_funcs,
470
sizeof(TupleHashEntryData),
474
if (!subplan->unknownEqFalse)
477
nbuckets = 1; /* there can only be one entry */
484
node->hashnulls = BuildTupleHashTable(ncols,
487
node->tab_hash_funcs,
489
sizeof(TupleHashEntryData),
495
* We are probably in a short-lived expression-evaluation context. Switch
496
* to the per-query context for manipulating the child plan.
498
oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
501
* Reset subplan to start.
503
ExecReScan(planstate);
506
* Scan the subplan and load the hash table(s). Note that when there are
507
* duplicate rows coming out of the sub-select, only one copy is stored.
509
for (slot = ExecProcNode(planstate);
511
slot = ExecProcNode(planstate))
518
* Load up the Params representing the raw sub-select outputs, then
519
* form the projection tuple to store in the hashtable.
521
foreach(plst, subplan->paramIds)
523
int paramid = lfirst_int(plst);
524
ParamExecData *prmdata;
526
prmdata = &(innerecontext->ecxt_param_exec_vals[paramid]);
527
Assert(prmdata->execPlan == NULL);
528
prmdata->value = slot_getattr(slot, col,
532
slot = ExecProject(node->projRight, NULL);
535
* If result contains any nulls, store separately or not at all.
537
if (slotNoNulls(slot))
539
(void) LookupTupleHashEntry(node->hashtable, slot, &isnew);
540
node->havehashrows = true;
542
else if (node->hashnulls)
544
(void) LookupTupleHashEntry(node->hashnulls, slot, &isnew);
545
node->havenullrows = true;
549
* Reset innerecontext after each inner tuple to free any memory used
550
* during ExecProject.
552
ResetExprContext(innerecontext);
556
* Since the projected tuples are in the sub-query's context and not the
557
* main context, we'd better clear the tuple slot before there's any
558
* chance of a reset of the sub-query's context. Else we will have the
559
* potential for a double free attempt. (XXX possibly no longer needed,
562
ExecClearTuple(node->projRight->pi_slot);
564
MemoryContextSwitchTo(oldcontext);
568
* findPartialMatch: does the hashtable contain an entry that is not
569
* provably distinct from the tuple?
571
* We have to scan the whole hashtable; we can't usefully use hashkeys
572
* to guide probing, since we might get partial matches on tuples with
573
* hashkeys quite unrelated to what we'd get from the given tuple.
576
findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot)
578
int numCols = hashtable->numCols;
579
AttrNumber *keyColIdx = hashtable->keyColIdx;
580
TupleHashIterator hashiter;
581
TupleHashEntry entry;
583
InitTupleHashIterator(hashtable, &hashiter);
584
while ((entry = ScanTupleHashTable(&hashiter)) != NULL)
586
ExecStoreMinimalTuple(entry->firstTuple, hashtable->tableslot, false);
587
if (!execTuplesUnequal(slot, hashtable->tableslot,
589
hashtable->cur_eq_funcs,
592
TermTupleHashIterator(&hashiter);
596
/* No TermTupleHashIterator call needed here */
601
* slotAllNulls: is the slot completely NULL?
603
* This does not test for dropped columns, which is OK because we only
604
* use it on projected tuples.
607
slotAllNulls(TupleTableSlot *slot)
609
int ncols = slot->tts_tupleDescriptor->natts;
612
for (i = 1; i <= ncols; i++)
614
if (!slot_attisnull(slot, i))
621
* slotNoNulls: is the slot entirely not NULL?
623
* This does not test for dropped columns, which is OK because we only
624
* use it on projected tuples.
627
slotNoNulls(TupleTableSlot *slot)
629
int ncols = slot->tts_tupleDescriptor->natts;
632
for (i = 1; i <= ncols; i++)
634
if (slot_attisnull(slot, i))
640
/* ----------------------------------------------------------------
643
* Create a SubPlanState for a SubPlan; this is the SubPlan-specific part
644
* of ExecInitExpr(). We split it out so that it can be used for InitPlans
645
* as well as regular SubPlans. Note that we don't link the SubPlan into
646
* the parent's subPlan list, because that shouldn't happen for InitPlans.
647
* Instead, ExecInitExpr() does that one part.
648
* ----------------------------------------------------------------
651
ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
653
SubPlanState *sstate = makeNode(SubPlanState);
654
EState *estate = parent->state;
656
sstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecSubPlan;
657
sstate->xprstate.expr = (Expr *) subplan;
659
/* Link the SubPlanState to already-initialized subplan */
660
sstate->planstate = (PlanState *) list_nth(estate->es_subplanstates,
661
subplan->plan_id - 1);
663
/* Initialize subexpressions */
664
sstate->testexpr = ExecInitExpr((Expr *) subplan->testexpr, parent);
665
sstate->args = (List *) ExecInitExpr((Expr *) subplan->args, parent);
668
* initialize my state
670
sstate->curTuple = NULL;
671
sstate->projLeft = NULL;
672
sstate->projRight = NULL;
673
sstate->hashtable = NULL;
674
sstate->hashnulls = NULL;
675
sstate->hashtablecxt = NULL;
676
sstate->hashtempcxt = NULL;
677
sstate->innerecontext = NULL;
678
sstate->keyColIdx = NULL;
679
sstate->tab_hash_funcs = NULL;
680
sstate->tab_eq_funcs = NULL;
681
sstate->lhs_hash_funcs = NULL;
682
sstate->cur_eq_funcs = NULL;
685
* If this plan is un-correlated or undirect correlated one and want to
686
* set params for parent plan then mark parameters as needing evaluation.
688
* A CTE subplan's output parameter is never to be evaluated in the normal
689
* way, so skip this in that case.
691
* Note that in the case of un-correlated subqueries we don't care about
692
* setting parent->chgParam here: indices take care about it, for others -
693
* it doesn't matter...
695
if (subplan->setParam != NIL && subplan->subLinkType != CTE_SUBLINK)
699
foreach(lst, subplan->setParam)
701
int paramid = lfirst_int(lst);
702
ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
704
prm->execPlan = sstate;
709
* If we are going to hash the subquery output, initialize relevant stuff.
710
* (We don't create the hashtable until needed, though.)
712
if (subplan->useHashTable)
717
TupleTableSlot *slot;
725
/* We need a memory context to hold the hash table(s) */
726
sstate->hashtablecxt =
727
AllocSetContextCreate(CurrentMemoryContext,
728
"Subplan HashTable Context",
729
ALLOCSET_DEFAULT_MINSIZE,
730
ALLOCSET_DEFAULT_INITSIZE,
731
ALLOCSET_DEFAULT_MAXSIZE);
732
/* and a small one for the hash tables to use as temp storage */
733
sstate->hashtempcxt =
734
AllocSetContextCreate(CurrentMemoryContext,
735
"Subplan HashTable Temp Context",
736
ALLOCSET_SMALL_MINSIZE,
737
ALLOCSET_SMALL_INITSIZE,
738
ALLOCSET_SMALL_MAXSIZE);
739
/* and a short-lived exprcontext for function evaluation */
740
sstate->innerecontext = CreateExprContext(estate);
741
/* Silly little array of column numbers 1..n */
742
ncols = list_length(subplan->paramIds);
743
sstate->keyColIdx = (AttrNumber *) palloc(ncols * sizeof(AttrNumber));
744
for (i = 0; i < ncols; i++)
745
sstate->keyColIdx[i] = i + 1;
748
* We use ExecProject to evaluate the lefthand and righthand
749
* expression lists and form tuples. (You might think that we could
750
* use the sub-select's output tuples directly, but that is not the
751
* case if we had to insert any run-time coercions of the sub-select's
752
* output datatypes; anyway this avoids storing any resjunk columns
753
* that might be in the sub-select's output.) Run through the
754
* combining expressions to build tlists for the lefthand and
755
* righthand sides. We need both the ExprState list (for ExecProject)
756
* and the underlying parse Exprs (for ExecTypeFromTL).
758
* We also extract the combining operators themselves to initialize
759
* the equality and hashing functions for the hash tables.
761
if (IsA(sstate->testexpr->expr, OpExpr))
763
/* single combining operator */
764
oplist = list_make1(sstate->testexpr);
766
else if (and_clause((Node *) sstate->testexpr->expr))
768
/* multiple combining operators */
769
Assert(IsA(sstate->testexpr, BoolExprState));
770
oplist = ((BoolExprState *) sstate->testexpr)->args;
774
/* shouldn't see anything else in a hashable subplan */
775
elog(ERROR, "unrecognized testexpr type: %d",
776
(int) nodeTag(sstate->testexpr->expr));
777
oplist = NIL; /* keep compiler quiet */
779
Assert(list_length(oplist) == ncols);
781
lefttlist = righttlist = NIL;
782
leftptlist = rightptlist = NIL;
783
sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
784
sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
785
sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
786
sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
790
FuncExprState *fstate = (FuncExprState *) lfirst(l);
791
OpExpr *opexpr = (OpExpr *) fstate->xprstate.expr;
795
GenericExprState *tlestate;
800
Assert(IsA(fstate, FuncExprState));
801
Assert(IsA(opexpr, OpExpr));
802
Assert(list_length(fstate->args) == 2);
804
/* Process lefthand argument */
805
exstate = (ExprState *) linitial(fstate->args);
806
expr = exstate->expr;
807
tle = makeTargetEntry(expr,
811
tlestate = makeNode(GenericExprState);
812
tlestate->xprstate.expr = (Expr *) tle;
813
tlestate->xprstate.evalfunc = NULL;
814
tlestate->arg = exstate;
815
lefttlist = lappend(lefttlist, tlestate);
816
leftptlist = lappend(leftptlist, tle);
818
/* Process righthand argument */
819
exstate = (ExprState *) lsecond(fstate->args);
820
expr = exstate->expr;
821
tle = makeTargetEntry(expr,
825
tlestate = makeNode(GenericExprState);
826
tlestate->xprstate.expr = (Expr *) tle;
827
tlestate->xprstate.evalfunc = NULL;
828
tlestate->arg = exstate;
829
righttlist = lappend(righttlist, tlestate);
830
rightptlist = lappend(rightptlist, tle);
832
/* Lookup the equality function (potentially cross-type) */
833
fmgr_info(opexpr->opfuncid, &sstate->cur_eq_funcs[i - 1]);
834
fmgr_info_set_expr((Node *) opexpr, &sstate->cur_eq_funcs[i - 1]);
836
/* Look up the equality function for the RHS type */
837
if (!get_compatible_hash_operators(opexpr->opno,
839
elog(ERROR, "could not find compatible hash operator for operator %u",
841
fmgr_info(get_opcode(rhs_eq_oper), &sstate->tab_eq_funcs[i - 1]);
843
/* Lookup the associated hash functions */
844
if (!get_op_hash_functions(opexpr->opno,
845
&left_hashfn, &right_hashfn))
846
elog(ERROR, "could not find hash function for hash operator %u",
848
fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
849
fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
855
* Construct tupdescs, slots and projection nodes for left and right
856
* sides. The lefthand expressions will be evaluated in the parent
857
* plan node's exprcontext, which we don't have access to here.
858
* Fortunately we can just pass NULL for now and fill it in later
859
* (hack alert!). The righthand expressions will be evaluated in our
862
tupDesc = ExecTypeFromTL(leftptlist, false);
863
slot = ExecInitExtraTupleSlot(estate);
864
ExecSetSlotDescriptor(slot, tupDesc);
865
sstate->projLeft = ExecBuildProjectionInfo(lefttlist,
870
tupDesc = ExecTypeFromTL(rightptlist, false);
871
slot = ExecInitExtraTupleSlot(estate);
872
ExecSetSlotDescriptor(slot, tupDesc);
873
sstate->projRight = ExecBuildProjectionInfo(righttlist,
874
sstate->innerecontext,
882
/* ----------------------------------------------------------------
885
* Executes an InitPlan subplan and sets its output parameters.
887
* This is called from ExecEvalParamExec() when the value of a PARAM_EXEC
888
* parameter is requested and the param's execPlan field is set (indicating
889
* that the param has not yet been evaluated). This allows lazy evaluation
890
* of initplans: we don't run the subplan until/unless we need its output.
891
* Note that this routine MUST clear the execPlan fields of the plan's
892
* output parameters after evaluating them!
893
* ----------------------------------------------------------------
896
ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
898
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
899
PlanState *planstate = node->planstate;
900
SubLinkType subLinkType = subplan->subLinkType;
901
MemoryContext oldcontext;
902
TupleTableSlot *slot;
905
ArrayBuildState *astate = NULL;
907
if (subLinkType == ANY_SUBLINK ||
908
subLinkType == ALL_SUBLINK)
909
elog(ERROR, "ANY/ALL subselect unsupported as initplan");
910
if (subLinkType == CTE_SUBLINK)
911
elog(ERROR, "CTE subplans should not be executed via ExecSetParamPlan");
914
* Must switch to per-query memory context.
916
oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
919
* Run the plan. (If it needs to be rescanned, the first ExecProcNode
920
* call will take care of that.)
922
for (slot = ExecProcNode(planstate);
924
slot = ExecProcNode(planstate))
926
TupleDesc tdesc = slot->tts_tupleDescriptor;
929
if (subLinkType == EXISTS_SUBLINK)
931
/* There can be only one setParam... */
932
int paramid = linitial_int(subplan->setParam);
933
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
935
prm->execPlan = NULL;
936
prm->value = BoolGetDatum(true);
942
if (subLinkType == ARRAY_SUBLINK)
948
/* stash away current value */
949
Assert(subplan->firstColType == tdesc->attrs[0]->atttypid);
950
dvalue = slot_getattr(slot, 1, &disnull);
951
astate = accumArrayResult(astate, dvalue, disnull,
952
subplan->firstColType, oldcontext);
953
/* keep scanning subplan to collect all values */
958
(subLinkType == EXPR_SUBLINK ||
959
subLinkType == ROWCOMPARE_SUBLINK))
961
(errcode(ERRCODE_CARDINALITY_VIOLATION),
962
errmsg("more than one row returned by a subquery used as an expression")));
967
* We need to copy the subplan's tuple into our own context, in case
968
* any of the params are pass-by-ref type --- the pointers stored in
969
* the param structs will point at this copied tuple! node->curTuple
970
* keeps track of the copied tuple for eventual freeing.
973
heap_freetuple(node->curTuple);
974
node->curTuple = ExecCopySlotTuple(slot);
977
* Now set all the setParam params from the columns of the tuple
979
foreach(l, subplan->setParam)
981
int paramid = lfirst_int(l);
982
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
984
prm->execPlan = NULL;
985
prm->value = heap_getattr(node->curTuple, i, tdesc,
991
if (subLinkType == ARRAY_SUBLINK)
993
/* There can be only one setParam... */
994
int paramid = linitial_int(subplan->setParam);
995
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
997
prm->execPlan = NULL;
998
/* We build the result in query context so it won't disappear */
1000
prm->value = makeArrayResult(astate,
1001
econtext->ecxt_per_query_memory);
1004
MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
1005
prm->value = PointerGetDatum(construct_empty_array(subplan->firstColType));
1007
prm->isnull = false;
1011
if (subLinkType == EXISTS_SUBLINK)
1013
/* There can be only one setParam... */
1014
int paramid = linitial_int(subplan->setParam);
1015
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1017
prm->execPlan = NULL;
1018
prm->value = BoolGetDatum(false);
1019
prm->isnull = false;
1023
foreach(l, subplan->setParam)
1025
int paramid = lfirst_int(l);
1026
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
1028
prm->execPlan = NULL;
1029
prm->value = (Datum) 0;
1035
MemoryContextSwitchTo(oldcontext);
1039
* Mark an initplan as needing recalculation
1042
ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent)
1044
PlanState *planstate = node->planstate;
1045
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
1046
EState *estate = parent->state;
1050
if (subplan->parParam != NIL)
1051
elog(ERROR, "direct correlated subquery unsupported as initplan");
1052
if (subplan->setParam == NIL)
1053
elog(ERROR, "setParam list of initplan is empty");
1054
if (bms_is_empty(planstate->plan->extParam))
1055
elog(ERROR, "extParam set of initplan is empty");
1058
* Don't actually re-scan: it'll happen inside ExecSetParamPlan if needed.
1062
* Mark this subplan's output parameters as needing recalculation.
1064
* CTE subplans are never executed via parameter recalculation; instead
1065
* they get run when called by nodeCtescan.c. So don't mark the output
1066
* parameter of a CTE subplan as dirty, but do set the chgParam bit for it
1067
* so that dependent plan nodes will get told to rescan.
1069
foreach(l, subplan->setParam)
1071
int paramid = lfirst_int(l);
1072
ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
1074
if (subplan->subLinkType != CTE_SUBLINK)
1075
prm->execPlan = node;
1077
parent->chgParam = bms_add_member(parent->chgParam, paramid);
1083
* ExecInitAlternativeSubPlan
1085
* Initialize for execution of one of a set of alternative subplans.
1087
AlternativeSubPlanState *
1088
ExecInitAlternativeSubPlan(AlternativeSubPlan *asplan, PlanState *parent)
1090
AlternativeSubPlanState *asstate = makeNode(AlternativeSubPlanState);
1097
asstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecAlternativeSubPlan;
1098
asstate->xprstate.expr = (Expr *) asplan;
1101
* Initialize subplans. (Can we get away with only initializing the one
1102
* we're going to use?)
1104
asstate->subplans = (List *) ExecInitExpr((Expr *) asplan->subplans,
1108
* Select the one to be used. For this, we need an estimate of the number
1109
* of executions of the subplan. We use the number of output rows
1110
* expected from the parent plan node. This is a good estimate if we are
1111
* in the parent's targetlist, and an underestimate (but probably not by
1112
* more than a factor of 2) if we are in the qual.
1114
num_calls = parent->plan->plan_rows;
1117
* The planner saved enough info so that we don't have to work very hard
1118
* to estimate the total cost, given the number-of-calls estimate.
1120
Assert(list_length(asplan->subplans) == 2);
1121
subplan1 = (SubPlan *) linitial(asplan->subplans);
1122
subplan2 = (SubPlan *) lsecond(asplan->subplans);
1124
cost1 = subplan1->startup_cost + num_calls * subplan1->per_call_cost;
1125
cost2 = subplan2->startup_cost + num_calls * subplan2->per_call_cost;
1128
asstate->active = 0;
1130
asstate->active = 1;
1136
* ExecAlternativeSubPlan
1138
* Execute one of a set of alternative subplans.
1140
* Note: in future we might consider changing to different subplans on the
1141
* fly, in case the original rowcount estimate turns out to be way off.
1144
ExecAlternativeSubPlan(AlternativeSubPlanState *node,
1145
ExprContext *econtext,
1147
ExprDoneCond *isDone)
1149
/* Just pass control to the active subplan */
1150
SubPlanState *activesp = (SubPlanState *) list_nth(node->subplans,
1153
Assert(IsA(activesp, SubPlanState));
1155
return ExecSubPlan(activesp,
added
removed
src/backend/executor/nodeSubplan.c
