/*------------------------------------------------------------------------- * * 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) 1996-2020, 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 #include #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 = list_length(subplan->paramIds); 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); node->havehashrows = true; } else if (node->hashnulls) { (void) LookupTupleHashEntry(node->hashnulls, slot, &isnew); 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); /* ... and to its parent's state */ 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); /* Silly little array of column numbers 1..n */ ncols = list_length(subplan->paramIds); sstate->keyColIdx = (AttrNumber *) palloc(ncols * sizeof(AttrNumber)); for (i = 0; i < ncols; i++) sstate->keyColIdx[i] = i + 1; /* * 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 */ } Assert(list_length(oplist) == ncols); lefttlist = righttlist = NIL; sstate->tab_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid)); sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo)); sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo)); sstate->tab_collations = (Oid *) palloc(ncols * sizeof(Oid)); 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; 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); } } /* * ExecInitAlternativeSubPlan * * Initialize for execution of one of a set of alternative subplans. */ AlternativeSubPlanState * ExecInitAlternativeSubPlan(AlternativeSubPlan *asplan, PlanState *parent) { AlternativeSubPlanState *asstate = makeNode(AlternativeSubPlanState); double num_calls; SubPlan *subplan1; SubPlan *subplan2; Cost cost1; Cost cost2; ListCell *lc; asstate->subplan = asplan; /* * Initialize subplans. (Can we get away with only initializing the one * we're going to use?) */ foreach(lc, asplan->subplans) { SubPlan *sp = lfirst_node(SubPlan, lc); SubPlanState *sps = ExecInitSubPlan(sp, parent); asstate->subplans = lappend(asstate->subplans, sps); parent->subPlan = lappend(parent->subPlan, sps); } /* * Select the one to be used. For this, we need an estimate of the number * of executions of the subplan. We use the number of output rows * expected from the parent plan node. This is a good estimate if we are * in the parent's targetlist, and an underestimate (but probably not by * more than a factor of 2) if we are in the qual. */ num_calls = parent->plan->plan_rows; /* * The planner saved enough info so that we don't have to work very hard * to estimate the total cost, given the number-of-calls estimate. */ Assert(list_length(asplan->subplans) == 2); subplan1 = (SubPlan *) linitial(asplan->subplans); subplan2 = (SubPlan *) lsecond(asplan->subplans); cost1 = subplan1->startup_cost + num_calls * subplan1->per_call_cost; cost2 = subplan2->startup_cost + num_calls * subplan2->per_call_cost; if (cost1 < cost2) asstate->active = 0; else asstate->active = 1; return asstate; } /* * ExecAlternativeSubPlan * * Execute one of a set of alternative subplans. * * Note: in future we might consider changing to different subplans on the * fly, in case the original rowcount estimate turns out to be way off. */ Datum ExecAlternativeSubPlan(AlternativeSubPlanState *node, ExprContext *econtext, bool *isNull) { /* Just pass control to the active subplan */ SubPlanState *activesp = list_nth_node(SubPlanState, node->subplans, node->active); return ExecSubPlan(activesp, econtext, isNull); }