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Diffstat (limited to 'src/backend/executor/nodeSubplan.c')
| -rw-r--r-- | src/backend/executor/nodeSubplan.c | 1313 |
1 files changed, 1313 insertions, 0 deletions
diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c new file mode 100644 index 0000000..d46227e --- /dev/null +++ b/src/backend/executor/nodeSubplan.c @@ -0,0 +1,1313 @@ +/*------------------------------------------------------------------------- + * + * nodeSubplan.c + * routines to support sub-selects appearing in expressions + * + * This module is concerned with executing SubPlan expression nodes, which + * should not be confused with sub-SELECTs appearing in FROM. SubPlans are + * divided into "initplans", which are those that need only one evaluation per + * query (among other restrictions, this requires that they don't use any + * direct correlation variables from the parent plan level), and "regular" + * subplans, which are re-evaluated every time their result is required. + * + * + * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * IDENTIFICATION + * src/backend/executor/nodeSubplan.c + * + *------------------------------------------------------------------------- + */ +/* + * INTERFACE ROUTINES + * ExecSubPlan - process a subselect + * ExecInitSubPlan - initialize a subselect + */ +#include "postgres.h" + +#include <limits.h> +#include <math.h> + +#include "access/htup_details.h" +#include "executor/executor.h" +#include "executor/nodeSubplan.h" +#include "miscadmin.h" +#include "nodes/makefuncs.h" +#include "nodes/nodeFuncs.h" +#include "utils/array.h" +#include "utils/lsyscache.h" +#include "utils/memutils.h" + +static Datum ExecHashSubPlan(SubPlanState *node, + ExprContext *econtext, + bool *isNull); +static Datum ExecScanSubPlan(SubPlanState *node, + ExprContext *econtext, + bool *isNull); +static void buildSubPlanHash(SubPlanState *node, ExprContext *econtext); +static bool findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot, + FmgrInfo *eqfunctions); +static bool slotAllNulls(TupleTableSlot *slot); +static bool slotNoNulls(TupleTableSlot *slot); + + +/* ---------------------------------------------------------------- + * ExecSubPlan + * + * This is the main entry point for execution of a regular SubPlan. + * ---------------------------------------------------------------- + */ +Datum +ExecSubPlan(SubPlanState *node, + ExprContext *econtext, + bool *isNull) +{ + SubPlan *subplan = node->subplan; + EState *estate = node->planstate->state; + ScanDirection dir = estate->es_direction; + Datum retval; + + CHECK_FOR_INTERRUPTS(); + + /* Set non-null as default */ + *isNull = false; + + /* Sanity checks */ + if (subplan->subLinkType == CTE_SUBLINK) + elog(ERROR, "CTE subplans should not be executed via ExecSubPlan"); + if (subplan->setParam != NIL && subplan->subLinkType != MULTIEXPR_SUBLINK) + elog(ERROR, "cannot set parent params from subquery"); + + /* Force forward-scan mode for evaluation */ + estate->es_direction = ForwardScanDirection; + + /* Select appropriate evaluation strategy */ + if (subplan->useHashTable) + retval = ExecHashSubPlan(node, econtext, isNull); + else + retval = ExecScanSubPlan(node, econtext, isNull); + + /* restore scan direction */ + estate->es_direction = dir; + + return retval; +} + +/* + * ExecHashSubPlan: store subselect result in an in-memory hash table + */ +static Datum +ExecHashSubPlan(SubPlanState *node, + ExprContext *econtext, + bool *isNull) +{ + SubPlan *subplan = node->subplan; + PlanState *planstate = node->planstate; + TupleTableSlot *slot; + + /* Shouldn't have any direct correlation Vars */ + if (subplan->parParam != NIL || node->args != NIL) + elog(ERROR, "hashed subplan with direct correlation not supported"); + + /* + * If first time through or we need to rescan the subplan, build the hash + * table. + */ + if (node->hashtable == NULL || planstate->chgParam != NULL) + buildSubPlanHash(node, econtext); + + /* + * The result for an empty subplan is always FALSE; no need to evaluate + * lefthand side. + */ + *isNull = false; + if (!node->havehashrows && !node->havenullrows) + return BoolGetDatum(false); + + /* + * Evaluate lefthand expressions and form a projection tuple. First we + * have to set the econtext to use (hack alert!). + */ + node->projLeft->pi_exprContext = econtext; + slot = ExecProject(node->projLeft); + + /* + * Note: because we are typically called in a per-tuple context, we have + * to explicitly clear the projected tuple before returning. Otherwise, + * we'll have a double-free situation: the per-tuple context will probably + * be reset before we're called again, and then the tuple slot will think + * it still needs to free the tuple. + */ + + /* + * If the LHS is all non-null, probe for an exact match in the main hash + * table. If we find one, the result is TRUE. Otherwise, scan the + * partly-null table to see if there are any rows that aren't provably + * unequal to the LHS; if so, the result is UNKNOWN. (We skip that part + * if we don't care about UNKNOWN.) Otherwise, the result is FALSE. + * + * Note: the reason we can avoid a full scan of the main hash table is + * that the combining operators are assumed never to yield NULL when both + * inputs are non-null. If they were to do so, we might need to produce + * UNKNOWN instead of FALSE because of an UNKNOWN result in comparing the + * LHS to some main-table entry --- which is a comparison we will not even + * make, unless there's a chance match of hash keys. + */ + if (slotNoNulls(slot)) + { + if (node->havehashrows && + FindTupleHashEntry(node->hashtable, + slot, + node->cur_eq_comp, + node->lhs_hash_funcs) != NULL) + { + ExecClearTuple(slot); + return BoolGetDatum(true); + } + if (node->havenullrows && + findPartialMatch(node->hashnulls, slot, node->cur_eq_funcs)) + { + ExecClearTuple(slot); + *isNull = true; + return BoolGetDatum(false); + } + ExecClearTuple(slot); + return BoolGetDatum(false); + } + + /* + * When the LHS is partly or wholly NULL, we can never return TRUE. If we + * don't care about UNKNOWN, just return FALSE. Otherwise, if the LHS is + * wholly NULL, immediately return UNKNOWN. (Since the combining + * operators are strict, the result could only be FALSE if the sub-select + * were empty, but we already handled that case.) Otherwise, we must scan + * both the main and partly-null tables to see if there are any rows that + * aren't provably unequal to the LHS; if so, the result is UNKNOWN. + * Otherwise, the result is FALSE. + */ + if (node->hashnulls == NULL) + { + ExecClearTuple(slot); + return BoolGetDatum(false); + } + if (slotAllNulls(slot)) + { + ExecClearTuple(slot); + *isNull = true; + return BoolGetDatum(false); + } + /* Scan partly-null table first, since more likely to get a match */ + if (node->havenullrows && + findPartialMatch(node->hashnulls, slot, node->cur_eq_funcs)) + { + ExecClearTuple(slot); + *isNull = true; + return BoolGetDatum(false); + } + if (node->havehashrows && + findPartialMatch(node->hashtable, slot, node->cur_eq_funcs)) + { + ExecClearTuple(slot); + *isNull = true; + return BoolGetDatum(false); + } + ExecClearTuple(slot); + return BoolGetDatum(false); +} + +/* + * ExecScanSubPlan: default case where we have to rescan subplan each time + */ +static Datum +ExecScanSubPlan(SubPlanState *node, + ExprContext *econtext, + bool *isNull) +{ + SubPlan *subplan = node->subplan; + PlanState *planstate = node->planstate; + SubLinkType subLinkType = subplan->subLinkType; + MemoryContext oldcontext; + TupleTableSlot *slot; + Datum result; + bool found = false; /* true if got at least one subplan tuple */ + ListCell *pvar; + ListCell *l; + ArrayBuildStateAny *astate = NULL; + + /* + * MULTIEXPR subplans, when "executed", just return NULL; but first we + * mark the subplan's output parameters as needing recalculation. (This + * is a bit of a hack: it relies on the subplan appearing later in its + * targetlist than any of the referencing Params, so that all the Params + * have been evaluated before we re-mark them for the next evaluation + * cycle. But in general resjunk tlist items appear after non-resjunk + * ones, so this should be safe.) Unlike ExecReScanSetParamPlan, we do + * *not* set bits in the parent plan node's chgParam, because we don't + * want to cause a rescan of the parent. + */ + if (subLinkType == MULTIEXPR_SUBLINK) + { + EState *estate = node->parent->state; + + foreach(l, subplan->setParam) + { + int paramid = lfirst_int(l); + ParamExecData *prm = &(estate->es_param_exec_vals[paramid]); + + prm->execPlan = node; + } + *isNull = true; + return (Datum) 0; + } + + /* Initialize ArrayBuildStateAny in caller's context, if needed */ + if (subLinkType == ARRAY_SUBLINK) + astate = initArrayResultAny(subplan->firstColType, + CurrentMemoryContext, true); + + /* + * We are probably in a short-lived expression-evaluation context. Switch + * to the per-query context for manipulating the child plan's chgParam, + * calling ExecProcNode on it, etc. + */ + oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory); + + /* + * Set Params of this plan from parent plan correlation values. (Any + * calculation we have to do is done in the parent econtext, since the + * Param values don't need to have per-query lifetime.) + */ + Assert(list_length(subplan->parParam) == list_length(node->args)); + + forboth(l, subplan->parParam, pvar, node->args) + { + int paramid = lfirst_int(l); + ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]); + + prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar), + econtext, + &(prm->isnull)); + planstate->chgParam = bms_add_member(planstate->chgParam, paramid); + } + + /* + * Now that we've set up its parameters, we can reset the subplan. + */ + ExecReScan(planstate); + + /* + * For all sublink types except EXPR_SUBLINK and ARRAY_SUBLINK, the result + * is boolean as are the results of the combining operators. We combine + * results across tuples (if the subplan produces more than one) using OR + * semantics for ANY_SUBLINK or AND semantics for ALL_SUBLINK. + * (ROWCOMPARE_SUBLINK doesn't allow multiple tuples from the subplan.) + * NULL results from the combining operators are handled according to the + * usual SQL semantics for OR and AND. The result for no input tuples is + * FALSE for ANY_SUBLINK, TRUE for ALL_SUBLINK, NULL for + * ROWCOMPARE_SUBLINK. + * + * For EXPR_SUBLINK we require the subplan to produce no more than one + * tuple, else an error is raised. If zero tuples are produced, we return + * NULL. Assuming we get a tuple, we just use its first column (there can + * be only one non-junk column in this case). + * + * For ARRAY_SUBLINK we allow the subplan to produce any number of tuples, + * and form an array of the first column's values. Note in particular + * that we produce a zero-element array if no tuples are produced (this is + * a change from pre-8.3 behavior of returning NULL). + */ + result = BoolGetDatum(subLinkType == ALL_SUBLINK); + *isNull = false; + + for (slot = ExecProcNode(planstate); + !TupIsNull(slot); + slot = ExecProcNode(planstate)) + { + TupleDesc tdesc = slot->tts_tupleDescriptor; + Datum rowresult; + bool rownull; + int col; + ListCell *plst; + + if (subLinkType == EXISTS_SUBLINK) + { + found = true; + result = BoolGetDatum(true); + break; + } + + if (subLinkType == EXPR_SUBLINK) + { + /* cannot allow multiple input tuples for EXPR sublink */ + if (found) + ereport(ERROR, + (errcode(ERRCODE_CARDINALITY_VIOLATION), + errmsg("more than one row returned by a subquery used as an expression"))); + found = true; + + /* + * We need to copy the subplan's tuple in case the result is of + * pass-by-ref type --- our return value will point into this + * copied tuple! Can't use the subplan's instance of the tuple + * since it won't still be valid after next ExecProcNode() call. + * node->curTuple keeps track of the copied tuple for eventual + * freeing. + */ + if (node->curTuple) + heap_freetuple(node->curTuple); + node->curTuple = ExecCopySlotHeapTuple(slot); + + result = heap_getattr(node->curTuple, 1, tdesc, isNull); + /* keep scanning subplan to make sure there's only one tuple */ + continue; + } + + if (subLinkType == ARRAY_SUBLINK) + { + Datum dvalue; + bool disnull; + + found = true; + /* stash away current value */ + Assert(subplan->firstColType == TupleDescAttr(tdesc, 0)->atttypid); + dvalue = slot_getattr(slot, 1, &disnull); + astate = accumArrayResultAny(astate, dvalue, disnull, + subplan->firstColType, oldcontext); + /* keep scanning subplan to collect all values */ + continue; + } + + /* cannot allow multiple input tuples for ROWCOMPARE sublink either */ + if (subLinkType == ROWCOMPARE_SUBLINK && found) + ereport(ERROR, + (errcode(ERRCODE_CARDINALITY_VIOLATION), + errmsg("more than one row returned by a subquery used as an expression"))); + + found = true; + + /* + * For ALL, ANY, and ROWCOMPARE sublinks, load up the Params + * representing the columns of the sub-select, and then evaluate the + * combining expression. + */ + col = 1; + foreach(plst, subplan->paramIds) + { + int paramid = lfirst_int(plst); + ParamExecData *prmdata; + + prmdata = &(econtext->ecxt_param_exec_vals[paramid]); + Assert(prmdata->execPlan == NULL); + prmdata->value = slot_getattr(slot, col, &(prmdata->isnull)); + col++; + } + + rowresult = ExecEvalExprSwitchContext(node->testexpr, econtext, + &rownull); + + if (subLinkType == ANY_SUBLINK) + { + /* combine across rows per OR semantics */ + if (rownull) + *isNull = true; + else if (DatumGetBool(rowresult)) + { + result = BoolGetDatum(true); + *isNull = false; + break; /* needn't look at any more rows */ + } + } + else if (subLinkType == ALL_SUBLINK) + { + /* combine across rows per AND semantics */ + if (rownull) + *isNull = true; + else if (!DatumGetBool(rowresult)) + { + result = BoolGetDatum(false); + *isNull = false; + break; /* needn't look at any more rows */ + } + } + else + { + /* must be ROWCOMPARE_SUBLINK */ + result = rowresult; + *isNull = rownull; + } + } + + MemoryContextSwitchTo(oldcontext); + + if (subLinkType == ARRAY_SUBLINK) + { + /* We return the result in the caller's context */ + result = makeArrayResultAny(astate, oldcontext, true); + } + else if (!found) + { + /* + * deal with empty subplan result. result/isNull were previously + * initialized correctly for all sublink types except EXPR and + * ROWCOMPARE; for those, return NULL. + */ + if (subLinkType == EXPR_SUBLINK || + subLinkType == ROWCOMPARE_SUBLINK) + { + result = (Datum) 0; + *isNull = true; + } + } + + return result; +} + +/* + * buildSubPlanHash: load hash table by scanning subplan output. + */ +static void +buildSubPlanHash(SubPlanState *node, ExprContext *econtext) +{ + SubPlan *subplan = node->subplan; + PlanState *planstate = node->planstate; + int ncols = node->numCols; + ExprContext *innerecontext = node->innerecontext; + MemoryContext oldcontext; + long nbuckets; + TupleTableSlot *slot; + + Assert(subplan->subLinkType == ANY_SUBLINK); + + /* + * If we already had any hash tables, reset 'em; otherwise create empty + * hash table(s). + * + * If we need to distinguish accurately between FALSE and UNKNOWN (i.e., + * NULL) results of the IN operation, then we have to store subplan output + * rows that are partly or wholly NULL. We store such rows in a separate + * hash table that we expect will be much smaller than the main table. (We + * can use hashing to eliminate partly-null rows that are not distinct. We + * keep them separate to minimize the cost of the inevitable full-table + * searches; see findPartialMatch.) + * + * If it's not necessary to distinguish FALSE and UNKNOWN, then we don't + * need to store subplan output rows that contain NULL. + */ + MemoryContextReset(node->hashtablecxt); + node->havehashrows = false; + node->havenullrows = false; + + nbuckets = (long) Min(planstate->plan->plan_rows, (double) LONG_MAX); + if (nbuckets < 1) + nbuckets = 1; + + if (node->hashtable) + ResetTupleHashTable(node->hashtable); + else + node->hashtable = BuildTupleHashTableExt(node->parent, + node->descRight, + ncols, + node->keyColIdx, + node->tab_eq_funcoids, + node->tab_hash_funcs, + node->tab_collations, + nbuckets, + 0, + node->planstate->state->es_query_cxt, + node->hashtablecxt, + node->hashtempcxt, + false); + + if (!subplan->unknownEqFalse) + { + if (ncols == 1) + nbuckets = 1; /* there can only be one entry */ + else + { + nbuckets /= 16; + if (nbuckets < 1) + nbuckets = 1; + } + + if (node->hashnulls) + ResetTupleHashTable(node->hashnulls); + else + node->hashnulls = BuildTupleHashTableExt(node->parent, + node->descRight, + ncols, + node->keyColIdx, + node->tab_eq_funcoids, + node->tab_hash_funcs, + node->tab_collations, + nbuckets, + 0, + node->planstate->state->es_query_cxt, + node->hashtablecxt, + node->hashtempcxt, + false); + } + else + node->hashnulls = NULL; + + /* + * We are probably in a short-lived expression-evaluation context. Switch + * to the per-query context for manipulating the child plan. + */ + oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory); + + /* + * Reset subplan to start. + */ + ExecReScan(planstate); + + /* + * Scan the subplan and load the hash table(s). Note that when there are + * duplicate rows coming out of the sub-select, only one copy is stored. + */ + for (slot = ExecProcNode(planstate); + !TupIsNull(slot); + slot = ExecProcNode(planstate)) + { + int col = 1; + ListCell *plst; + bool isnew; + + /* + * Load up the Params representing the raw sub-select outputs, then + * form the projection tuple to store in the hashtable. + */ + foreach(plst, subplan->paramIds) + { + int paramid = lfirst_int(plst); + ParamExecData *prmdata; + + prmdata = &(innerecontext->ecxt_param_exec_vals[paramid]); + Assert(prmdata->execPlan == NULL); + prmdata->value = slot_getattr(slot, col, + &(prmdata->isnull)); + col++; + } + slot = ExecProject(node->projRight); + + /* + * If result contains any nulls, store separately or not at all. + */ + if (slotNoNulls(slot)) + { + (void) LookupTupleHashEntry(node->hashtable, slot, &isnew, NULL); + node->havehashrows = true; + } + else if (node->hashnulls) + { + (void) LookupTupleHashEntry(node->hashnulls, slot, &isnew, NULL); + node->havenullrows = true; + } + + /* + * Reset innerecontext after each inner tuple to free any memory used + * during ExecProject. + */ + ResetExprContext(innerecontext); + } + + /* + * Since the projected tuples are in the sub-query's context and not the + * main context, we'd better clear the tuple slot before there's any + * chance of a reset of the sub-query's context. Else we will have the + * potential for a double free attempt. (XXX possibly no longer needed, + * but can't hurt.) + */ + ExecClearTuple(node->projRight->pi_state.resultslot); + + MemoryContextSwitchTo(oldcontext); +} + +/* + * execTuplesUnequal + * Return true if two tuples are definitely unequal in the indicated + * fields. + * + * Nulls are neither equal nor unequal to anything else. A true result + * is obtained only if there are non-null fields that compare not-equal. + * + * slot1, slot2: the tuples to compare (must have same columns!) + * numCols: the number of attributes to be examined + * matchColIdx: array of attribute column numbers + * eqFunctions: array of fmgr lookup info for the equality functions to use + * evalContext: short-term memory context for executing the functions + */ +static bool +execTuplesUnequal(TupleTableSlot *slot1, + TupleTableSlot *slot2, + int numCols, + AttrNumber *matchColIdx, + FmgrInfo *eqfunctions, + const Oid *collations, + MemoryContext evalContext) +{ + MemoryContext oldContext; + bool result; + int i; + + /* Reset and switch into the temp context. */ + MemoryContextReset(evalContext); + oldContext = MemoryContextSwitchTo(evalContext); + + /* + * We cannot report a match without checking all the fields, but we can + * report a non-match as soon as we find unequal fields. So, start + * comparing at the last field (least significant sort key). That's the + * most likely to be different if we are dealing with sorted input. + */ + result = false; + + for (i = numCols; --i >= 0;) + { + AttrNumber att = matchColIdx[i]; + Datum attr1, + attr2; + bool isNull1, + isNull2; + + attr1 = slot_getattr(slot1, att, &isNull1); + + if (isNull1) + continue; /* can't prove anything here */ + + attr2 = slot_getattr(slot2, att, &isNull2); + + if (isNull2) + continue; /* can't prove anything here */ + + /* Apply the type-specific equality function */ + if (!DatumGetBool(FunctionCall2Coll(&eqfunctions[i], + collations[i], + attr1, attr2))) + { + result = true; /* they are unequal */ + break; + } + } + + MemoryContextSwitchTo(oldContext); + + return result; +} + +/* + * findPartialMatch: does the hashtable contain an entry that is not + * provably distinct from the tuple? + * + * We have to scan the whole hashtable; we can't usefully use hashkeys + * to guide probing, since we might get partial matches on tuples with + * hashkeys quite unrelated to what we'd get from the given tuple. + * + * Caller must provide the equality functions to use, since in cross-type + * cases these are different from the hashtable's internal functions. + */ +static bool +findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot, + FmgrInfo *eqfunctions) +{ + int numCols = hashtable->numCols; + AttrNumber *keyColIdx = hashtable->keyColIdx; + TupleHashIterator hashiter; + TupleHashEntry entry; + + InitTupleHashIterator(hashtable, &hashiter); + while ((entry = ScanTupleHashTable(hashtable, &hashiter)) != NULL) + { + CHECK_FOR_INTERRUPTS(); + + ExecStoreMinimalTuple(entry->firstTuple, hashtable->tableslot, false); + if (!execTuplesUnequal(slot, hashtable->tableslot, + numCols, keyColIdx, + eqfunctions, + hashtable->tab_collations, + hashtable->tempcxt)) + { + TermTupleHashIterator(&hashiter); + return true; + } + } + /* No TermTupleHashIterator call needed here */ + return false; +} + +/* + * slotAllNulls: is the slot completely NULL? + * + * This does not test for dropped columns, which is OK because we only + * use it on projected tuples. + */ +static bool +slotAllNulls(TupleTableSlot *slot) +{ + int ncols = slot->tts_tupleDescriptor->natts; + int i; + + for (i = 1; i <= ncols; i++) + { + if (!slot_attisnull(slot, i)) + return false; + } + return true; +} + +/* + * slotNoNulls: is the slot entirely not NULL? + * + * This does not test for dropped columns, which is OK because we only + * use it on projected tuples. + */ +static bool +slotNoNulls(TupleTableSlot *slot) +{ + int ncols = slot->tts_tupleDescriptor->natts; + int i; + + for (i = 1; i <= ncols; i++) + { + if (slot_attisnull(slot, i)) + return false; + } + return true; +} + +/* ---------------------------------------------------------------- + * ExecInitSubPlan + * + * Create a SubPlanState for a SubPlan; this is the SubPlan-specific part + * of ExecInitExpr(). We split it out so that it can be used for InitPlans + * as well as regular SubPlans. Note that we don't link the SubPlan into + * the parent's subPlan list, because that shouldn't happen for InitPlans. + * Instead, ExecInitExpr() does that one part. + * ---------------------------------------------------------------- + */ +SubPlanState * +ExecInitSubPlan(SubPlan *subplan, PlanState *parent) +{ + SubPlanState *sstate = makeNode(SubPlanState); + EState *estate = parent->state; + + sstate->subplan = subplan; + + /* Link the SubPlanState to already-initialized subplan */ + sstate->planstate = (PlanState *) list_nth(estate->es_subplanstates, + subplan->plan_id - 1); + + /* + * This check can fail if the planner mistakenly puts a parallel-unsafe + * subplan into a parallelized subquery; see ExecSerializePlan. + */ + if (sstate->planstate == NULL) + elog(ERROR, "subplan \"%s\" was not initialized", + subplan->plan_name); + + /* Link to parent's state, too */ + sstate->parent = parent; + + /* Initialize subexpressions */ + sstate->testexpr = ExecInitExpr((Expr *) subplan->testexpr, parent); + sstate->args = ExecInitExprList(subplan->args, parent); + + /* + * initialize my state + */ + sstate->curTuple = NULL; + sstate->curArray = PointerGetDatum(NULL); + sstate->projLeft = NULL; + sstate->projRight = NULL; + sstate->hashtable = NULL; + sstate->hashnulls = NULL; + sstate->hashtablecxt = NULL; + sstate->hashtempcxt = NULL; + sstate->innerecontext = NULL; + sstate->keyColIdx = NULL; + sstate->tab_eq_funcoids = NULL; + sstate->tab_hash_funcs = NULL; + sstate->tab_eq_funcs = NULL; + sstate->tab_collations = NULL; + sstate->lhs_hash_funcs = NULL; + sstate->cur_eq_funcs = NULL; + + /* + * If this is an initplan or MULTIEXPR subplan, it has output parameters + * that the parent plan will use, so mark those parameters as needing + * evaluation. We don't actually run the subplan until we first need one + * of its outputs. + * + * A CTE subplan's output parameter is never to be evaluated in the normal + * way, so skip this in that case. + * + * Note that we don't set parent->chgParam here: the parent plan hasn't + * been run yet, so no need to force it to re-run. + */ + if (subplan->setParam != NIL && subplan->subLinkType != CTE_SUBLINK) + { + ListCell *lst; + + foreach(lst, subplan->setParam) + { + int paramid = lfirst_int(lst); + ParamExecData *prm = &(estate->es_param_exec_vals[paramid]); + + prm->execPlan = sstate; + } + } + + /* + * If we are going to hash the subquery output, initialize relevant stuff. + * (We don't create the hashtable until needed, though.) + */ + if (subplan->useHashTable) + { + int ncols, + i; + TupleDesc tupDescLeft; + TupleDesc tupDescRight; + Oid *cross_eq_funcoids; + TupleTableSlot *slot; + List *oplist, + *lefttlist, + *righttlist; + ListCell *l; + + /* We need a memory context to hold the hash table(s) */ + sstate->hashtablecxt = + AllocSetContextCreate(CurrentMemoryContext, + "Subplan HashTable Context", + ALLOCSET_DEFAULT_SIZES); + /* and a small one for the hash tables to use as temp storage */ + sstate->hashtempcxt = + AllocSetContextCreate(CurrentMemoryContext, + "Subplan HashTable Temp Context", + ALLOCSET_SMALL_SIZES); + /* and a short-lived exprcontext for function evaluation */ + sstate->innerecontext = CreateExprContext(estate); + + /* + * We use ExecProject to evaluate the lefthand and righthand + * expression lists and form tuples. (You might think that we could + * use the sub-select's output tuples directly, but that is not the + * case if we had to insert any run-time coercions of the sub-select's + * output datatypes; anyway this avoids storing any resjunk columns + * that might be in the sub-select's output.) Run through the + * combining expressions to build tlists for the lefthand and + * righthand sides. + * + * We also extract the combining operators themselves to initialize + * the equality and hashing functions for the hash tables. + */ + if (IsA(subplan->testexpr, OpExpr)) + { + /* single combining operator */ + oplist = list_make1(subplan->testexpr); + } + else if (is_andclause(subplan->testexpr)) + { + /* multiple combining operators */ + oplist = castNode(BoolExpr, subplan->testexpr)->args; + } + else + { + /* shouldn't see anything else in a hashable subplan */ + elog(ERROR, "unrecognized testexpr type: %d", + (int) nodeTag(subplan->testexpr)); + oplist = NIL; /* keep compiler quiet */ + } + ncols = list_length(oplist); + + lefttlist = righttlist = NIL; + sstate->numCols = ncols; + sstate->keyColIdx = (AttrNumber *) palloc(ncols * sizeof(AttrNumber)); + sstate->tab_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid)); + sstate->tab_collations = (Oid *) palloc(ncols * sizeof(Oid)); + sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo)); + sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo)); + sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo)); + sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo)); + /* we'll need the cross-type equality fns below, but not in sstate */ + cross_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid)); + + i = 1; + foreach(l, oplist) + { + OpExpr *opexpr = lfirst_node(OpExpr, l); + Expr *expr; + TargetEntry *tle; + Oid rhs_eq_oper; + Oid left_hashfn; + Oid right_hashfn; + + Assert(list_length(opexpr->args) == 2); + + /* Process lefthand argument */ + expr = (Expr *) linitial(opexpr->args); + tle = makeTargetEntry(expr, + i, + NULL, + false); + lefttlist = lappend(lefttlist, tle); + + /* Process righthand argument */ + expr = (Expr *) lsecond(opexpr->args); + tle = makeTargetEntry(expr, + i, + NULL, + false); + righttlist = lappend(righttlist, tle); + + /* Lookup the equality function (potentially cross-type) */ + cross_eq_funcoids[i - 1] = opexpr->opfuncid; + fmgr_info(opexpr->opfuncid, &sstate->cur_eq_funcs[i - 1]); + fmgr_info_set_expr((Node *) opexpr, &sstate->cur_eq_funcs[i - 1]); + + /* Look up the equality function for the RHS type */ + if (!get_compatible_hash_operators(opexpr->opno, + NULL, &rhs_eq_oper)) + elog(ERROR, "could not find compatible hash operator for operator %u", + opexpr->opno); + sstate->tab_eq_funcoids[i - 1] = get_opcode(rhs_eq_oper); + fmgr_info(sstate->tab_eq_funcoids[i - 1], + &sstate->tab_eq_funcs[i - 1]); + + /* Lookup the associated hash functions */ + if (!get_op_hash_functions(opexpr->opno, + &left_hashfn, &right_hashfn)) + elog(ERROR, "could not find hash function for hash operator %u", + opexpr->opno); + fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]); + fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]); + + /* Set collation */ + sstate->tab_collations[i - 1] = opexpr->inputcollid; + + /* keyColIdx is just column numbers 1..n */ + sstate->keyColIdx[i - 1] = i; + + i++; + } + + /* + * Construct tupdescs, slots and projection nodes for left and right + * sides. The lefthand expressions will be evaluated in the parent + * plan node's exprcontext, which we don't have access to here. + * Fortunately we can just pass NULL for now and fill it in later + * (hack alert!). The righthand expressions will be evaluated in our + * own innerecontext. + */ + tupDescLeft = ExecTypeFromTL(lefttlist); + slot = ExecInitExtraTupleSlot(estate, tupDescLeft, &TTSOpsVirtual); + sstate->projLeft = ExecBuildProjectionInfo(lefttlist, + NULL, + slot, + parent, + NULL); + + sstate->descRight = tupDescRight = ExecTypeFromTL(righttlist); + slot = ExecInitExtraTupleSlot(estate, tupDescRight, &TTSOpsVirtual); + sstate->projRight = ExecBuildProjectionInfo(righttlist, + sstate->innerecontext, + slot, + sstate->planstate, + NULL); + + /* + * Create comparator for lookups of rows in the table (potentially + * cross-type comparisons). + */ + sstate->cur_eq_comp = ExecBuildGroupingEqual(tupDescLeft, tupDescRight, + &TTSOpsVirtual, &TTSOpsMinimalTuple, + ncols, + sstate->keyColIdx, + cross_eq_funcoids, + sstate->tab_collations, + parent); + } + + return sstate; +} + +/* ---------------------------------------------------------------- + * ExecSetParamPlan + * + * Executes a subplan and sets its output parameters. + * + * This is called from ExecEvalParamExec() when the value of a PARAM_EXEC + * parameter is requested and the param's execPlan field is set (indicating + * that the param has not yet been evaluated). This allows lazy evaluation + * of initplans: we don't run the subplan until/unless we need its output. + * Note that this routine MUST clear the execPlan fields of the plan's + * output parameters after evaluating them! + * + * The results of this function are stored in the EState associated with the + * ExprContext (particularly, its ecxt_param_exec_vals); any pass-by-ref + * result Datums are allocated in the EState's per-query memory. The passed + * econtext can be any ExprContext belonging to that EState; which one is + * important only to the extent that the ExprContext's per-tuple memory + * context is used to evaluate any parameters passed down to the subplan. + * (Thus in principle, the shorter-lived the ExprContext the better, since + * that data isn't needed after we return. In practice, because initplan + * parameters are never more complex than Vars, Aggrefs, etc, evaluating them + * currently never leaks any memory anyway.) + * ---------------------------------------------------------------- + */ +void +ExecSetParamPlan(SubPlanState *node, ExprContext *econtext) +{ + SubPlan *subplan = node->subplan; + PlanState *planstate = node->planstate; + SubLinkType subLinkType = subplan->subLinkType; + EState *estate = planstate->state; + ScanDirection dir = estate->es_direction; + MemoryContext oldcontext; + TupleTableSlot *slot; + ListCell *pvar; + ListCell *l; + bool found = false; + ArrayBuildStateAny *astate = NULL; + + if (subLinkType == ANY_SUBLINK || + subLinkType == ALL_SUBLINK) + elog(ERROR, "ANY/ALL subselect unsupported as initplan"); + if (subLinkType == CTE_SUBLINK) + elog(ERROR, "CTE subplans should not be executed via ExecSetParamPlan"); + + /* + * Enforce forward scan direction regardless of caller. It's hard but not + * impossible to get here in backward scan, so make it work anyway. + */ + estate->es_direction = ForwardScanDirection; + + /* Initialize ArrayBuildStateAny in caller's context, if needed */ + if (subLinkType == ARRAY_SUBLINK) + astate = initArrayResultAny(subplan->firstColType, + CurrentMemoryContext, true); + + /* + * Must switch to per-query memory context. + */ + oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory); + + /* + * Set Params of this plan from parent plan correlation values. (Any + * calculation we have to do is done in the parent econtext, since the + * Param values don't need to have per-query lifetime.) Currently, we + * expect only MULTIEXPR_SUBLINK plans to have any correlation values. + */ + Assert(subplan->parParam == NIL || subLinkType == MULTIEXPR_SUBLINK); + Assert(list_length(subplan->parParam) == list_length(node->args)); + + forboth(l, subplan->parParam, pvar, node->args) + { + int paramid = lfirst_int(l); + ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]); + + prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar), + econtext, + &(prm->isnull)); + planstate->chgParam = bms_add_member(planstate->chgParam, paramid); + } + + /* + * Run the plan. (If it needs to be rescanned, the first ExecProcNode + * call will take care of that.) + */ + for (slot = ExecProcNode(planstate); + !TupIsNull(slot); + slot = ExecProcNode(planstate)) + { + TupleDesc tdesc = slot->tts_tupleDescriptor; + int i = 1; + + if (subLinkType == EXISTS_SUBLINK) + { + /* There can be only one setParam... */ + int paramid = linitial_int(subplan->setParam); + ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]); + + prm->execPlan = NULL; + prm->value = BoolGetDatum(true); + prm->isnull = false; + found = true; + break; + } + + if (subLinkType == ARRAY_SUBLINK) + { + Datum dvalue; + bool disnull; + + found = true; + /* stash away current value */ + Assert(subplan->firstColType == TupleDescAttr(tdesc, 0)->atttypid); + dvalue = slot_getattr(slot, 1, &disnull); + astate = accumArrayResultAny(astate, dvalue, disnull, + subplan->firstColType, oldcontext); + /* keep scanning subplan to collect all values */ + continue; + } + + if (found && + (subLinkType == EXPR_SUBLINK || + subLinkType == MULTIEXPR_SUBLINK || + subLinkType == ROWCOMPARE_SUBLINK)) + ereport(ERROR, + (errcode(ERRCODE_CARDINALITY_VIOLATION), + errmsg("more than one row returned by a subquery used as an expression"))); + + found = true; + + /* + * We need to copy the subplan's tuple into our own context, in case + * any of the params are pass-by-ref type --- the pointers stored in + * the param structs will point at this copied tuple! node->curTuple + * keeps track of the copied tuple for eventual freeing. + */ + if (node->curTuple) + heap_freetuple(node->curTuple); + node->curTuple = ExecCopySlotHeapTuple(slot); + + /* + * Now set all the setParam params from the columns of the tuple + */ + foreach(l, subplan->setParam) + { + int paramid = lfirst_int(l); + ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]); + + prm->execPlan = NULL; + prm->value = heap_getattr(node->curTuple, i, tdesc, + &(prm->isnull)); + i++; + } + } + + if (subLinkType == ARRAY_SUBLINK) + { + /* There can be only one setParam... */ + int paramid = linitial_int(subplan->setParam); + ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]); + + /* + * We build the result array in query context so it won't disappear; + * to avoid leaking memory across repeated calls, we have to remember + * the latest value, much as for curTuple above. + */ + if (node->curArray != PointerGetDatum(NULL)) + pfree(DatumGetPointer(node->curArray)); + node->curArray = makeArrayResultAny(astate, + econtext->ecxt_per_query_memory, + true); + prm->execPlan = NULL; + prm->value = node->curArray; + prm->isnull = false; + } + else if (!found) + { + if (subLinkType == EXISTS_SUBLINK) + { + /* There can be only one setParam... */ + int paramid = linitial_int(subplan->setParam); + ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]); + + prm->execPlan = NULL; + prm->value = BoolGetDatum(false); + prm->isnull = false; + } + else + { + /* For other sublink types, set all the output params to NULL */ + foreach(l, subplan->setParam) + { + int paramid = lfirst_int(l); + ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]); + + prm->execPlan = NULL; + prm->value = (Datum) 0; + prm->isnull = true; + } + } + } + + MemoryContextSwitchTo(oldcontext); + + /* restore scan direction */ + estate->es_direction = dir; +} + +/* + * ExecSetParamPlanMulti + * + * Apply ExecSetParamPlan to evaluate any not-yet-evaluated initplan output + * parameters whose ParamIDs are listed in "params". Any listed params that + * are not initplan outputs are ignored. + * + * As with ExecSetParamPlan, any ExprContext belonging to the current EState + * can be used, but in principle a shorter-lived ExprContext is better than a + * longer-lived one. + */ +void +ExecSetParamPlanMulti(const Bitmapset *params, ExprContext *econtext) +{ + int paramid; + + paramid = -1; + while ((paramid = bms_next_member(params, paramid)) >= 0) + { + ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]); + + if (prm->execPlan != NULL) + { + /* Parameter not evaluated yet, so go do it */ + ExecSetParamPlan(prm->execPlan, econtext); + /* ExecSetParamPlan should have processed this param... */ + Assert(prm->execPlan == NULL); + } + } +} + +/* + * Mark an initplan as needing recalculation + */ +void +ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent) +{ + PlanState *planstate = node->planstate; + SubPlan *subplan = node->subplan; + EState *estate = parent->state; + ListCell *l; + + /* sanity checks */ + if (subplan->parParam != NIL) + elog(ERROR, "direct correlated subquery unsupported as initplan"); + if (subplan->setParam == NIL) + elog(ERROR, "setParam list of initplan is empty"); + if (bms_is_empty(planstate->plan->extParam)) + elog(ERROR, "extParam set of initplan is empty"); + + /* + * Don't actually re-scan: it'll happen inside ExecSetParamPlan if needed. + */ + + /* + * Mark this subplan's output parameters as needing recalculation. + * + * CTE subplans are never executed via parameter recalculation; instead + * they get run when called by nodeCtescan.c. So don't mark the output + * parameter of a CTE subplan as dirty, but do set the chgParam bit for it + * so that dependent plan nodes will get told to rescan. + */ + foreach(l, subplan->setParam) + { + int paramid = lfirst_int(l); + ParamExecData *prm = &(estate->es_param_exec_vals[paramid]); + + if (subplan->subLinkType != CTE_SUBLINK) + prm->execPlan = node; + + parent->chgParam = bms_add_member(parent->chgParam, paramid); + } +} |