/*------------------------------------------------------------------------- * * execMain.c * top level executor interface routines * * INTERFACE ROUTINES * ExecutorStart() * ExecutorRun() * ExecutorEnd() * * The old ExecutorMain() has been replaced by ExecutorStart(), * ExecutorRun() and ExecutorEnd() * * These three procedures are the external interfaces to the executor. * In each case, the query descriptor is required as an argument. * * ExecutorStart() must be called at the beginning of execution of any * query plan and ExecutorEnd() should always be called at the end of * execution of a plan. * * ExecutorRun accepts direction and count arguments that specify whether * the plan is to be executed forwards, backwards, and for how many tuples. * * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.220 2003/10/01 21:30:52 tgl Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/heapam.h" #include "catalog/heap.h" #include "catalog/namespace.h" #include "commands/tablecmds.h" #include "commands/trigger.h" #include "executor/execdebug.h" #include "executor/execdefs.h" #include "miscadmin.h" #include "optimizer/var.h" #include "parser/parsetree.h" #include "utils/acl.h" #include "utils/lsyscache.h" typedef struct execRowMark { Relation relation; Index rti; char resname[32]; } execRowMark; typedef struct evalPlanQual { Index rti; EState *estate; PlanState *planstate; struct evalPlanQual *next; /* stack of active PlanQual plans */ struct evalPlanQual *free; /* list of free PlanQual plans */ } evalPlanQual; /* decls for local routines only used within this module */ static void InitPlan(QueryDesc *queryDesc, bool explainOnly); static void initResultRelInfo(ResultRelInfo *resultRelInfo, Index resultRelationIndex, List *rangeTable, CmdType operation); static TupleTableSlot *ExecutePlan(EState *estate, PlanState *planstate, CmdType operation, long numberTuples, ScanDirection direction, DestReceiver *dest); static void ExecSelect(TupleTableSlot *slot, DestReceiver *dest, EState *estate); static void ExecInsert(TupleTableSlot *slot, ItemPointer tupleid, EState *estate); static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid, EState *estate); static void ExecUpdate(TupleTableSlot *slot, ItemPointer tupleid, EState *estate); static TupleTableSlot *EvalPlanQualNext(EState *estate); static void EndEvalPlanQual(EState *estate); static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation); static void ExecCheckXactReadOnly(Query *parsetree, CmdType operation); static void EvalPlanQualStart(evalPlanQual *epq, EState *estate, evalPlanQual *priorepq); static void EvalPlanQualStop(evalPlanQual *epq); /* end of local decls */ /* ---------------------------------------------------------------- * ExecutorStart * * This routine must be called at the beginning of any execution of any * query plan * * Takes a QueryDesc previously created by CreateQueryDesc (it's not real * clear why we bother to separate the two functions, but...). The tupDesc * field of the QueryDesc is filled in to describe the tuples that will be * returned, and the internal fields (estate and planstate) are set up. * * If useCurrentSnapshot is true, run the query with the latest available * snapshot, instead of the normal QuerySnapshot. Also, if it's an update * or delete query, check that the rows to be updated or deleted would be * visible to the normal QuerySnapshot. (This is a special-case behavior * needed for referential integrity updates in serializable transactions. * We must check all currently-committed rows, but we want to throw a * can't-serialize error if any rows that would need updates would not be * visible under the normal serializable snapshot.) * * If explainOnly is true, we are not actually intending to run the plan, * only to set up for EXPLAIN; so skip unwanted side-effects. * * NB: the CurrentMemoryContext when this is called will become the parent * of the per-query context used for this Executor invocation. * ---------------------------------------------------------------- */ void ExecutorStart(QueryDesc *queryDesc, bool useCurrentSnapshot, bool explainOnly) { EState *estate; MemoryContext oldcontext; /* sanity checks: queryDesc must not be started already */ Assert(queryDesc != NULL); Assert(queryDesc->estate == NULL); /* * If the transaction is read-only, we need to check if any writes are * planned to non-temporary tables. */ if (!explainOnly) ExecCheckXactReadOnly(queryDesc->parsetree, queryDesc->operation); /* * Build EState, switch into per-query memory context for startup. */ estate = CreateExecutorState(); queryDesc->estate = estate; oldcontext = MemoryContextSwitchTo(estate->es_query_cxt); /* * Fill in parameters, if any, from queryDesc */ estate->es_param_list_info = queryDesc->params; if (queryDesc->plantree->nParamExec > 0) estate->es_param_exec_vals = (ParamExecData *) palloc0(queryDesc->plantree->nParamExec * sizeof(ParamExecData)); estate->es_instrument = queryDesc->doInstrument; /* * Make our own private copy of the current query snapshot data. * * This "freezes" our idea of which tuples are good and which are not for * the life of this query, even if it outlives the current command and * current snapshot. */ if (useCurrentSnapshot) { /* RI update/delete query --- must use an up-to-date snapshot */ estate->es_snapshot = CopyCurrentSnapshot(); /* crosscheck updates/deletes against transaction snapshot */ estate->es_crosscheck_snapshot = CopyQuerySnapshot(); } else { /* normal query --- use query snapshot, no crosscheck */ estate->es_snapshot = CopyQuerySnapshot(); estate->es_crosscheck_snapshot = SnapshotAny; } /* * Initialize the plan state tree */ InitPlan(queryDesc, explainOnly); MemoryContextSwitchTo(oldcontext); } /* ---------------------------------------------------------------- * ExecutorRun * * This is the main routine of the executor module. It accepts * the query descriptor from the traffic cop and executes the * query plan. * * ExecutorStart must have been called already. * * If direction is NoMovementScanDirection then nothing is done * except to start up/shut down the destination. Otherwise, * we retrieve up to 'count' tuples in the specified direction. * * Note: count = 0 is interpreted as no portal limit, i.e., run to * completion. * * ---------------------------------------------------------------- */ TupleTableSlot * ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, long count) { EState *estate; CmdType operation; DestReceiver *dest; TupleTableSlot *result; MemoryContext oldcontext; /* sanity checks */ Assert(queryDesc != NULL); estate = queryDesc->estate; Assert(estate != NULL); /* * Switch into per-query memory context */ oldcontext = MemoryContextSwitchTo(estate->es_query_cxt); /* * extract information from the query descriptor and the query * feature. */ operation = queryDesc->operation; dest = queryDesc->dest; /* * startup tuple receiver */ estate->es_processed = 0; estate->es_lastoid = InvalidOid; (*dest->rStartup) (dest, operation, queryDesc->tupDesc); /* * run plan */ if (direction == NoMovementScanDirection) result = NULL; else result = ExecutePlan(estate, queryDesc->planstate, operation, count, direction, dest); /* * shutdown receiver */ (*dest->rShutdown) (dest); MemoryContextSwitchTo(oldcontext); return result; } /* ---------------------------------------------------------------- * ExecutorEnd * * This routine must be called at the end of execution of any * query plan * ---------------------------------------------------------------- */ void ExecutorEnd(QueryDesc *queryDesc) { EState *estate; MemoryContext oldcontext; /* sanity checks */ Assert(queryDesc != NULL); estate = queryDesc->estate; Assert(estate != NULL); /* * Switch into per-query memory context to run ExecEndPlan */ oldcontext = MemoryContextSwitchTo(estate->es_query_cxt); ExecEndPlan(queryDesc->planstate, estate); /* * Must switch out of context before destroying it */ MemoryContextSwitchTo(oldcontext); /* * Release EState and per-query memory context. This should release * everything the executor has allocated. */ FreeExecutorState(estate); /* Reset queryDesc fields that no longer point to anything */ queryDesc->tupDesc = NULL; queryDesc->estate = NULL; queryDesc->planstate = NULL; } /* ---------------------------------------------------------------- * ExecutorRewind * * This routine may be called on an open queryDesc to rewind it * to the start. * ---------------------------------------------------------------- */ void ExecutorRewind(QueryDesc *queryDesc) { EState *estate; MemoryContext oldcontext; /* sanity checks */ Assert(queryDesc != NULL); estate = queryDesc->estate; Assert(estate != NULL); /* It's probably not sensible to rescan updating queries */ Assert(queryDesc->operation == CMD_SELECT); /* * Switch into per-query memory context */ oldcontext = MemoryContextSwitchTo(estate->es_query_cxt); /* * rescan plan */ ExecReScan(queryDesc->planstate, NULL); MemoryContextSwitchTo(oldcontext); } /* * ExecCheckRTPerms * Check access permissions for all relations listed in a range table. */ void ExecCheckRTPerms(List *rangeTable, CmdType operation) { List *lp; foreach(lp, rangeTable) { RangeTblEntry *rte = lfirst(lp); ExecCheckRTEPerms(rte, operation); } } /* * ExecCheckRTEPerms * Check access permissions for a single RTE. */ static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation) { Oid relOid; AclId userid; AclResult aclcheck_result; /* * If it's a subquery, recursively examine its rangetable. */ if (rte->rtekind == RTE_SUBQUERY) { ExecCheckRTPerms(rte->subquery->rtable, operation); return; } /* * Otherwise, only plain-relation RTEs need to be checked here. * Function RTEs are checked by init_fcache when the function is * prepared for execution. Join and special RTEs need no checks. */ if (rte->rtekind != RTE_RELATION) return; relOid = rte->relid; /* * userid to check as: current user unless we have a setuid * indication. * * Note: GetUserId() is presently fast enough that there's no harm in * calling it separately for each RTE. If that stops being true, we * could call it once in ExecCheckRTPerms and pass the userid down * from there. But for now, no need for the extra clutter. */ userid = rte->checkAsUser ? rte->checkAsUser : GetUserId(); #define CHECK(MODE) pg_class_aclcheck(relOid, userid, MODE) if (rte->checkForRead) { aclcheck_result = CHECK(ACL_SELECT); if (aclcheck_result != ACLCHECK_OK) aclcheck_error(aclcheck_result, ACL_KIND_CLASS, get_rel_name(relOid)); } if (rte->checkForWrite) { /* * Note: write access in a SELECT context means SELECT FOR UPDATE. * Right now we don't distinguish that from true update as far as * permissions checks are concerned. */ switch (operation) { case CMD_INSERT: aclcheck_result = CHECK(ACL_INSERT); break; case CMD_SELECT: case CMD_UPDATE: aclcheck_result = CHECK(ACL_UPDATE); break; case CMD_DELETE: aclcheck_result = CHECK(ACL_DELETE); break; default: elog(ERROR, "unrecognized operation code: %d", (int) operation); aclcheck_result = ACLCHECK_OK; /* keep compiler quiet */ break; } if (aclcheck_result != ACLCHECK_OK) aclcheck_error(aclcheck_result, ACL_KIND_CLASS, get_rel_name(relOid)); } } static void ExecCheckXactReadOnly(Query *parsetree, CmdType operation) { if (!XactReadOnly) return; /* CREATE TABLE AS or SELECT INTO */ if (operation == CMD_SELECT && parsetree->into != NULL) goto fail; if (operation == CMD_DELETE || operation == CMD_INSERT || operation == CMD_UPDATE) { List *lp; foreach(lp, parsetree->rtable) { RangeTblEntry *rte = lfirst(lp); if (rte->rtekind != RTE_RELATION) continue; if (!rte->checkForWrite) continue; if (isTempNamespace(get_rel_namespace(rte->relid))) continue; goto fail; } } return; fail: ereport(ERROR, (errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION), errmsg("transaction is read-only"))); } /* ---------------------------------------------------------------- * InitPlan * * Initializes the query plan: open files, allocate storage * and start up the rule manager * ---------------------------------------------------------------- */ static void InitPlan(QueryDesc *queryDesc, bool explainOnly) { CmdType operation = queryDesc->operation; Query *parseTree = queryDesc->parsetree; Plan *plan = queryDesc->plantree; EState *estate = queryDesc->estate; PlanState *planstate; List *rangeTable; Relation intoRelationDesc; bool do_select_into; TupleDesc tupType; /* * Do permissions checks. It's sufficient to examine the query's top * rangetable here --- subplan RTEs will be checked during * ExecInitSubPlan(). */ ExecCheckRTPerms(parseTree->rtable, operation); /* * get information from query descriptor */ rangeTable = parseTree->rtable; /* * initialize the node's execution state */ estate->es_range_table = rangeTable; /* * if there is a result relation, initialize result relation stuff */ if (parseTree->resultRelation != 0 && operation != CMD_SELECT) { List *resultRelations = parseTree->resultRelations; int numResultRelations; ResultRelInfo *resultRelInfos; if (resultRelations != NIL) { /* * Multiple result relations (due to inheritance) * parseTree->resultRelations identifies them all */ ResultRelInfo *resultRelInfo; numResultRelations = length(resultRelations); resultRelInfos = (ResultRelInfo *) palloc(numResultRelations * sizeof(ResultRelInfo)); resultRelInfo = resultRelInfos; while (resultRelations != NIL) { initResultRelInfo(resultRelInfo, lfirsti(resultRelations), rangeTable, operation); resultRelInfo++; resultRelations = lnext(resultRelations); } } else { /* * Single result relation identified by * parseTree->resultRelation */ numResultRelations = 1; resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo)); initResultRelInfo(resultRelInfos, parseTree->resultRelation, rangeTable, operation); } estate->es_result_relations = resultRelInfos; estate->es_num_result_relations = numResultRelations; /* Initialize to first or only result rel */ estate->es_result_relation_info = resultRelInfos; } else { /* * if no result relation, then set state appropriately */ estate->es_result_relations = NULL; estate->es_num_result_relations = 0; estate->es_result_relation_info = NULL; } /* * Detect whether we're doing SELECT INTO. If so, set the force_oids * flag appropriately so that the plan tree will be initialized with * the correct tuple descriptors. */ do_select_into = false; if (operation == CMD_SELECT && parseTree->into != NULL) { do_select_into = true; /* * For now, always create OIDs in SELECT INTO; this is for * backwards compatibility with pre-7.3 behavior. Eventually we * might want to allow the user to choose. */ estate->es_force_oids = true; } /* * Have to lock relations selected for update */ estate->es_rowMark = NIL; if (parseTree->rowMarks != NIL) { List *l; foreach(l, parseTree->rowMarks) { Index rti = lfirsti(l); Oid relid = getrelid(rti, rangeTable); Relation relation; execRowMark *erm; relation = heap_open(relid, RowShareLock); erm = (execRowMark *) palloc(sizeof(execRowMark)); erm->relation = relation; erm->rti = rti; snprintf(erm->resname, sizeof(erm->resname), "ctid%u", rti); estate->es_rowMark = lappend(estate->es_rowMark, erm); } } /* * initialize the executor "tuple" table. We need slots for all the * plan nodes, plus possibly output slots for the junkfilter(s). At * this point we aren't sure if we need junkfilters, so just add slots * for them unconditionally. */ { int nSlots = ExecCountSlotsNode(plan); if (parseTree->resultRelations != NIL) nSlots += length(parseTree->resultRelations); else nSlots += 1; estate->es_tupleTable = ExecCreateTupleTable(nSlots); } /* mark EvalPlanQual not active */ estate->es_topPlan = plan; estate->es_evalPlanQual = NULL; estate->es_evTupleNull = NULL; estate->es_evTuple = NULL; estate->es_useEvalPlan = false; /* * initialize the private state information for all the nodes in the * query tree. This opens files, allocates storage and leaves us * ready to start processing tuples. */ planstate = ExecInitNode(plan, estate); /* * Get the tuple descriptor describing the type of tuples to return. * (this is especially important if we are creating a relation with * "SELECT INTO") */ tupType = ExecGetResultType(planstate); /* * Initialize the junk filter if needed. SELECT and INSERT queries * need a filter if there are any junk attrs in the tlist. INSERT and * SELECT INTO also need a filter if the top plan node is a scan node * that's not doing projection (else we'll be scribbling on the scan * tuple!) UPDATE and DELETE always need a filter, since there's * always a junk 'ctid' attribute present --- no need to look first. */ { bool junk_filter_needed = false; List *tlist; switch (operation) { case CMD_SELECT: case CMD_INSERT: foreach(tlist, plan->targetlist) { TargetEntry *tle = (TargetEntry *) lfirst(tlist); if (tle->resdom->resjunk) { junk_filter_needed = true; break; } } if (!junk_filter_needed && (operation == CMD_INSERT || do_select_into)) { if (IsA(planstate, SeqScanState) || IsA(planstate, IndexScanState) || IsA(planstate, TidScanState) || IsA(planstate, SubqueryScanState) || IsA(planstate, FunctionScanState)) { if (planstate->ps_ProjInfo == NULL) junk_filter_needed = true; } } break; case CMD_UPDATE: case CMD_DELETE: junk_filter_needed = true; break; default: break; } if (junk_filter_needed) { /* * If there are multiple result relations, each one needs its * own junk filter. Note this is only possible for * UPDATE/DELETE, so we can't be fooled by some needing a * filter and some not. */ if (parseTree->resultRelations != NIL) { PlanState **appendplans; int as_nplans; ResultRelInfo *resultRelInfo; int i; /* Top plan had better be an Append here. */ Assert(IsA(plan, Append)); Assert(((Append *) plan)->isTarget); Assert(IsA(planstate, AppendState)); appendplans = ((AppendState *) planstate)->appendplans; as_nplans = ((AppendState *) planstate)->as_nplans; Assert(as_nplans == estate->es_num_result_relations); resultRelInfo = estate->es_result_relations; for (i = 0; i < as_nplans; i++) { PlanState *subplan = appendplans[i]; JunkFilter *j; j = ExecInitJunkFilter(subplan->plan->targetlist, ExecGetResultType(subplan), ExecAllocTableSlot(estate->es_tupleTable)); resultRelInfo->ri_junkFilter = j; resultRelInfo++; } /* * Set active junkfilter too; at this point ExecInitAppend * has already selected an active result relation... */ estate->es_junkFilter = estate->es_result_relation_info->ri_junkFilter; } else { /* Normal case with just one JunkFilter */ JunkFilter *j; j = ExecInitJunkFilter(planstate->plan->targetlist, tupType, ExecAllocTableSlot(estate->es_tupleTable)); estate->es_junkFilter = j; if (estate->es_result_relation_info) estate->es_result_relation_info->ri_junkFilter = j; /* For SELECT, want to return the cleaned tuple type */ if (operation == CMD_SELECT) tupType = j->jf_cleanTupType; } } else estate->es_junkFilter = NULL; } /* * If doing SELECT INTO, initialize the "into" relation. We must wait * till now so we have the "clean" result tuple type to create the new * table from. * * If EXPLAIN, skip creating the "into" relation. */ intoRelationDesc = (Relation) NULL; if (do_select_into && !explainOnly) { char *intoName; Oid namespaceId; AclResult aclresult; Oid intoRelationId; TupleDesc tupdesc; /* * find namespace to create in, check permissions */ intoName = parseTree->into->relname; namespaceId = RangeVarGetCreationNamespace(parseTree->into); aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_CREATE); if (aclresult != ACLCHECK_OK) aclcheck_error(aclresult, ACL_KIND_NAMESPACE, get_namespace_name(namespaceId)); /* * have to copy tupType to get rid of constraints */ tupdesc = CreateTupleDescCopy(tupType); intoRelationId = heap_create_with_catalog(intoName, namespaceId, tupdesc, RELKIND_RELATION, false, ONCOMMIT_NOOP, allowSystemTableMods); FreeTupleDesc(tupdesc); /* * Advance command counter so that the newly-created relation's * catalog tuples will be visible to heap_open. */ CommandCounterIncrement(); /* * If necessary, create a TOAST table for the into relation. Note * that AlterTableCreateToastTable ends with * CommandCounterIncrement(), so that the TOAST table will be * visible for insertion. */ AlterTableCreateToastTable(intoRelationId, true); /* * And open the constructed table for writing. */ intoRelationDesc = heap_open(intoRelationId, AccessExclusiveLock); } estate->es_into_relation_descriptor = intoRelationDesc; queryDesc->tupDesc = tupType; queryDesc->planstate = planstate; } /* * Initialize ResultRelInfo data for one result relation */ static void initResultRelInfo(ResultRelInfo *resultRelInfo, Index resultRelationIndex, List *rangeTable, CmdType operation) { Oid resultRelationOid; Relation resultRelationDesc; resultRelationOid = getrelid(resultRelationIndex, rangeTable); resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock); switch (resultRelationDesc->rd_rel->relkind) { case RELKIND_SEQUENCE: ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), errmsg("cannot change sequence \"%s\"", RelationGetRelationName(resultRelationDesc)))); break; case RELKIND_TOASTVALUE: ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), errmsg("cannot change TOAST relation \"%s\"", RelationGetRelationName(resultRelationDesc)))); break; case RELKIND_VIEW: ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), errmsg("cannot change view \"%s\"", RelationGetRelationName(resultRelationDesc)))); break; } MemSet(resultRelInfo, 0, sizeof(ResultRelInfo)); resultRelInfo->type = T_ResultRelInfo; resultRelInfo->ri_RangeTableIndex = resultRelationIndex; resultRelInfo->ri_RelationDesc = resultRelationDesc; resultRelInfo->ri_NumIndices = 0; resultRelInfo->ri_IndexRelationDescs = NULL; resultRelInfo->ri_IndexRelationInfo = NULL; /* make a copy so as not to depend on relcache info not changing... */ resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc); resultRelInfo->ri_TrigFunctions = NULL; resultRelInfo->ri_ConstraintExprs = NULL; resultRelInfo->ri_junkFilter = NULL; /* * If there are indices on the result relation, open them and save * descriptors in the result relation info, so that we can add new * index entries for the tuples we add/update. We need not do this * for a DELETE, however, since deletion doesn't affect indexes. */ if (resultRelationDesc->rd_rel->relhasindex && operation != CMD_DELETE) ExecOpenIndices(resultRelInfo); } /* ---------------------------------------------------------------- * ExecEndPlan * * Cleans up the query plan -- closes files and frees up storage * * NOTE: we are no longer very worried about freeing storage per se * in this code; FreeExecutorState should be guaranteed to release all * memory that needs to be released. What we are worried about doing * is closing relations and dropping buffer pins. Thus, for example, * tuple tables must be cleared or dropped to ensure pins are released. * ---------------------------------------------------------------- */ void ExecEndPlan(PlanState *planstate, EState *estate) { ResultRelInfo *resultRelInfo; int i; List *l; /* * shut down any PlanQual processing we were doing */ if (estate->es_evalPlanQual != NULL) EndEvalPlanQual(estate); /* * shut down the node-type-specific query processing */ ExecEndNode(planstate); /* * destroy the executor "tuple" table. */ ExecDropTupleTable(estate->es_tupleTable, true); estate->es_tupleTable = NULL; /* * close the result relation(s) if any, but hold locks until xact * commit. */ resultRelInfo = estate->es_result_relations; for (i = estate->es_num_result_relations; i > 0; i--) { /* Close indices and then the relation itself */ ExecCloseIndices(resultRelInfo); heap_close(resultRelInfo->ri_RelationDesc, NoLock); resultRelInfo++; } /* * close the "into" relation if necessary, again keeping lock */ if (estate->es_into_relation_descriptor != NULL) heap_close(estate->es_into_relation_descriptor, NoLock); /* * close any relations selected FOR UPDATE, again keeping locks */ foreach(l, estate->es_rowMark) { execRowMark *erm = lfirst(l); heap_close(erm->relation, NoLock); } } /* ---------------------------------------------------------------- * ExecutePlan * * processes the query plan to retrieve 'numberTuples' tuples in the * direction specified. * * Retrieves all tuples if numberTuples is 0 * * result is either a slot containing the last tuple in the case * of a SELECT or NULL otherwise. * * Note: the ctid attribute is a 'junk' attribute that is removed before the * user can see it * ---------------------------------------------------------------- */ static TupleTableSlot * ExecutePlan(EState *estate, PlanState *planstate, CmdType operation, long numberTuples, ScanDirection direction, DestReceiver *dest) { JunkFilter *junkfilter; TupleTableSlot *slot; ItemPointer tupleid = NULL; ItemPointerData tuple_ctid; long current_tuple_count; TupleTableSlot *result; /* * initialize local variables */ slot = NULL; current_tuple_count = 0; result = NULL; /* * Set the direction. */ estate->es_direction = direction; /* * Process BEFORE EACH STATEMENT triggers */ switch (operation) { case CMD_UPDATE: ExecBSUpdateTriggers(estate, estate->es_result_relation_info); break; case CMD_DELETE: ExecBSDeleteTriggers(estate, estate->es_result_relation_info); break; case CMD_INSERT: ExecBSInsertTriggers(estate, estate->es_result_relation_info); break; default: /* do nothing */ break; } /* * Loop until we've processed the proper number of tuples from the * plan. */ for (;;) { /* Reset the per-output-tuple exprcontext */ ResetPerTupleExprContext(estate); /* * Execute the plan and obtain a tuple */ lnext: ; if (estate->es_useEvalPlan) { slot = EvalPlanQualNext(estate); if (TupIsNull(slot)) slot = ExecProcNode(planstate); } else slot = ExecProcNode(planstate); /* * if the tuple is null, then we assume there is nothing more to * process so we just return null... */ if (TupIsNull(slot)) { result = NULL; break; } /* * if we have a junk filter, then project a new tuple with the * junk removed. * * Store this new "clean" tuple in the junkfilter's resultSlot. * (Formerly, we stored it back over the "dirty" tuple, which is * WRONG because that tuple slot has the wrong descriptor.) * * Also, extract all the junk information we need. */ if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL) { Datum datum; HeapTuple newTuple; bool isNull; /* * extract the 'ctid' junk attribute. */ if (operation == CMD_UPDATE || operation == CMD_DELETE) { if (!ExecGetJunkAttribute(junkfilter, slot, "ctid", &datum, &isNull)) elog(ERROR, "could not find junk ctid column"); /* shouldn't ever get a null result... */ if (isNull) elog(ERROR, "ctid is NULL"); tupleid = (ItemPointer) DatumGetPointer(datum); tuple_ctid = *tupleid; /* make sure we don't free the * ctid!! */ tupleid = &tuple_ctid; } else if (estate->es_rowMark != NIL) { List *l; lmark: ; foreach(l, estate->es_rowMark) { execRowMark *erm = lfirst(l); Buffer buffer; HeapTupleData tuple; TupleTableSlot *newSlot; int test; if (!ExecGetJunkAttribute(junkfilter, slot, erm->resname, &datum, &isNull)) elog(ERROR, "could not find junk \"%s\" column", erm->resname); /* shouldn't ever get a null result... */ if (isNull) elog(ERROR, "\"%s\" is NULL", erm->resname); tuple.t_self = *((ItemPointer) DatumGetPointer(datum)); test = heap_mark4update(erm->relation, &tuple, &buffer, estate->es_snapshot->curcid); ReleaseBuffer(buffer); switch (test) { case HeapTupleSelfUpdated: /* treat it as deleted; do not process */ goto lnext; case HeapTupleMayBeUpdated: break; case HeapTupleUpdated: if (XactIsoLevel == XACT_SERIALIZABLE) ereport(ERROR, (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE), errmsg("could not serialize access due to concurrent update"))); if (!(ItemPointerEquals(&(tuple.t_self), (ItemPointer) DatumGetPointer(datum)))) { newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self)); if (!(TupIsNull(newSlot))) { slot = newSlot; estate->es_useEvalPlan = true; goto lmark; } } /* * if tuple was deleted or PlanQual failed for * updated tuple - we must not return this * tuple! */ goto lnext; default: elog(ERROR, "unrecognized heap_mark4update status: %u", test); return (NULL); } } } /* * Finally create a new "clean" tuple with all junk attributes * removed */ newTuple = ExecRemoveJunk(junkfilter, slot); slot = ExecStoreTuple(newTuple, /* tuple to store */ junkfilter->jf_resultSlot, /* dest slot */ InvalidBuffer, /* this tuple has no * buffer */ true); /* tuple should be pfreed */ } /* * now that we have a tuple, do the appropriate thing with it.. * either return it to the user, add it to a relation someplace, * delete it from a relation, or modify some of its attributes. */ switch (operation) { case CMD_SELECT: ExecSelect(slot, /* slot containing tuple */ dest, /* destination's tuple-receiver obj */ estate); result = slot; break; case CMD_INSERT: ExecInsert(slot, tupleid, estate); result = NULL; break; case CMD_DELETE: ExecDelete(slot, tupleid, estate); result = NULL; break; case CMD_UPDATE: ExecUpdate(slot, tupleid, estate); result = NULL; break; default: elog(ERROR, "unrecognized operation code: %d", (int) operation); result = NULL; break; } /* * check our tuple count.. if we've processed the proper number * then quit, else loop again and process more tuples. Zero * numberTuples means no limit. */ current_tuple_count++; if (numberTuples && numberTuples == current_tuple_count) break; } /* * Process AFTER EACH STATEMENT triggers */ switch (operation) { case CMD_UPDATE: ExecASUpdateTriggers(estate, estate->es_result_relation_info); break; case CMD_DELETE: ExecASDeleteTriggers(estate, estate->es_result_relation_info); break; case CMD_INSERT: ExecASInsertTriggers(estate, estate->es_result_relation_info); break; default: /* do nothing */ break; } /* * here, result is either a slot containing a tuple in the case of a * SELECT or NULL otherwise. */ return result; } /* ---------------------------------------------------------------- * ExecSelect * * SELECTs are easy.. we just pass the tuple to the appropriate * print function. The only complexity is when we do a * "SELECT INTO", in which case we insert the tuple into * the appropriate relation (note: this is a newly created relation * so we don't need to worry about indices or locks.) * ---------------------------------------------------------------- */ static void ExecSelect(TupleTableSlot *slot, DestReceiver *dest, EState *estate) { HeapTuple tuple; TupleDesc attrtype; /* * get the heap tuple out of the tuple table slot */ tuple = slot->val; attrtype = slot->ttc_tupleDescriptor; /* * insert the tuple into the "into relation" * * XXX this probably ought to be replaced by a separate destination */ if (estate->es_into_relation_descriptor != NULL) { heap_insert(estate->es_into_relation_descriptor, tuple, estate->es_snapshot->curcid); IncrAppended(); } /* * send the tuple to the destination */ (*dest->receiveTuple) (tuple, attrtype, dest); IncrRetrieved(); (estate->es_processed)++; } /* ---------------------------------------------------------------- * ExecInsert * * INSERTs are trickier.. we have to insert the tuple into * the base relation and insert appropriate tuples into the * index relations. * ---------------------------------------------------------------- */ static void ExecInsert(TupleTableSlot *slot, ItemPointer tupleid, EState *estate) { HeapTuple tuple; ResultRelInfo *resultRelInfo; Relation resultRelationDesc; int numIndices; Oid newId; /* * get the heap tuple out of the tuple table slot */ tuple = slot->val; /* * get information on the (current) result relation */ resultRelInfo = estate->es_result_relation_info; resultRelationDesc = resultRelInfo->ri_RelationDesc; /* BEFORE ROW INSERT Triggers */ if (resultRelInfo->ri_TrigDesc && resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0) { HeapTuple newtuple; newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple); if (newtuple == NULL) /* "do nothing" */ return; if (newtuple != tuple) /* modified by Trigger(s) */ { /* * Insert modified tuple into tuple table slot, replacing the * original. We assume that it was allocated in per-tuple * memory context, and therefore will go away by itself. The * tuple table slot should not try to clear it. */ ExecStoreTuple(newtuple, slot, InvalidBuffer, false); tuple = newtuple; } } /* * Check the constraints of the tuple */ if (resultRelationDesc->rd_att->constr) ExecConstraints(resultRelInfo, slot, estate); /* * insert the tuple */ newId = heap_insert(resultRelationDesc, tuple, estate->es_snapshot->curcid); IncrAppended(); (estate->es_processed)++; estate->es_lastoid = newId; setLastTid(&(tuple->t_self)); /* * process indices * * Note: heap_insert adds a new tuple to a relation. As a side effect, * the tupleid of the new tuple is placed in the new tuple's t_ctid * field. */ numIndices = resultRelInfo->ri_NumIndices; if (numIndices > 0) ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false); /* AFTER ROW INSERT Triggers */ ExecARInsertTriggers(estate, resultRelInfo, tuple); } /* ---------------------------------------------------------------- * ExecDelete * * DELETE is like UPDATE, we delete the tuple and its * index tuples. * ---------------------------------------------------------------- */ static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid, EState *estate) { ResultRelInfo *resultRelInfo; Relation resultRelationDesc; ItemPointerData ctid; int result; /* * get information on the (current) result relation */ resultRelInfo = estate->es_result_relation_info; resultRelationDesc = resultRelInfo->ri_RelationDesc; /* BEFORE ROW DELETE Triggers */ if (resultRelInfo->ri_TrigDesc && resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0) { bool dodelete; dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid, estate->es_snapshot->curcid); if (!dodelete) /* "do nothing" */ return; } /* * delete the tuple */ ldelete:; result = heap_delete(resultRelationDesc, tupleid, &ctid, estate->es_snapshot->curcid, estate->es_crosscheck_snapshot, true /* wait for commit */); switch (result) { case HeapTupleSelfUpdated: /* already deleted by self; nothing to do */ return; case HeapTupleMayBeUpdated: break; case HeapTupleUpdated: if (XactIsoLevel == XACT_SERIALIZABLE) ereport(ERROR, (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE), errmsg("could not serialize access due to concurrent update"))); else if (!(ItemPointerEquals(tupleid, &ctid))) { TupleTableSlot *epqslot = EvalPlanQual(estate, resultRelInfo->ri_RangeTableIndex, &ctid); if (!TupIsNull(epqslot)) { *tupleid = ctid; goto ldelete; } } /* tuple already deleted; nothing to do */ return; default: elog(ERROR, "unrecognized heap_delete status: %u", result); return; } IncrDeleted(); (estate->es_processed)++; /* * Note: Normally one would think that we have to delete index tuples * associated with the heap tuple now.. * * ... but in POSTGRES, we have no need to do this because the vacuum * daemon automatically opens an index scan and deletes index tuples * when it finds deleted heap tuples. -cim 9/27/89 */ /* AFTER ROW DELETE Triggers */ ExecARDeleteTriggers(estate, resultRelInfo, tupleid); } /* ---------------------------------------------------------------- * ExecUpdate * * note: we can't run UPDATE queries with transactions * off because UPDATEs are actually INSERTs and our * scan will mistakenly loop forever, updating the tuple * it just inserted.. This should be fixed but until it * is, we don't want to get stuck in an infinite loop * which corrupts your database.. * ---------------------------------------------------------------- */ static void ExecUpdate(TupleTableSlot *slot, ItemPointer tupleid, EState *estate) { HeapTuple tuple; ResultRelInfo *resultRelInfo; Relation resultRelationDesc; ItemPointerData ctid; int result; int numIndices; /* * abort the operation if not running transactions */ if (IsBootstrapProcessingMode()) elog(ERROR, "cannot UPDATE during bootstrap"); /* * get the heap tuple out of the tuple table slot */ tuple = slot->val; /* * get information on the (current) result relation */ resultRelInfo = estate->es_result_relation_info; resultRelationDesc = resultRelInfo->ri_RelationDesc; /* BEFORE ROW UPDATE Triggers */ if (resultRelInfo->ri_TrigDesc && resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0) { HeapTuple newtuple; newtuple = ExecBRUpdateTriggers(estate, resultRelInfo, tupleid, tuple, estate->es_snapshot->curcid); if (newtuple == NULL) /* "do nothing" */ return; if (newtuple != tuple) /* modified by Trigger(s) */ { /* * Insert modified tuple into tuple table slot, replacing the * original. We assume that it was allocated in per-tuple * memory context, and therefore will go away by itself. The * tuple table slot should not try to clear it. */ ExecStoreTuple(newtuple, slot, InvalidBuffer, false); tuple = newtuple; } } /* * Check the constraints of the tuple * * If we generate a new candidate tuple after EvalPlanQual testing, we * must loop back here and recheck constraints. (We don't need to * redo triggers, however. If there are any BEFORE triggers then * trigger.c will have done mark4update to lock the correct tuple, so * there's no need to do them again.) */ lreplace:; if (resultRelationDesc->rd_att->constr) ExecConstraints(resultRelInfo, slot, estate); /* * replace the heap tuple */ result = heap_update(resultRelationDesc, tupleid, tuple, &ctid, estate->es_snapshot->curcid, estate->es_crosscheck_snapshot, true /* wait for commit */); switch (result) { case HeapTupleSelfUpdated: /* already deleted by self; nothing to do */ return; case HeapTupleMayBeUpdated: break; case HeapTupleUpdated: if (XactIsoLevel == XACT_SERIALIZABLE) ereport(ERROR, (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE), errmsg("could not serialize access due to concurrent update"))); else if (!(ItemPointerEquals(tupleid, &ctid))) { TupleTableSlot *epqslot = EvalPlanQual(estate, resultRelInfo->ri_RangeTableIndex, &ctid); if (!TupIsNull(epqslot)) { *tupleid = ctid; tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot); slot = ExecStoreTuple(tuple, estate->es_junkFilter->jf_resultSlot, InvalidBuffer, true); goto lreplace; } } /* tuple already deleted; nothing to do */ return; default: elog(ERROR, "unrecognized heap_update status: %u", result); return; } IncrReplaced(); (estate->es_processed)++; /* * Note: instead of having to update the old index tuples associated * with the heap tuple, all we do is form and insert new index tuples. * This is because UPDATEs are actually DELETEs and INSERTs and index * tuple deletion is done automagically by the vacuum daemon. All we * do is insert new index tuples. -cim 9/27/89 */ /* * process indices * * heap_update updates a tuple in the base relation by invalidating it * and then inserting a new tuple to the relation. As a side effect, * the tupleid of the new tuple is placed in the new tuple's t_ctid * field. So we now insert index tuples using the new tupleid stored * there. */ numIndices = resultRelInfo->ri_NumIndices; if (numIndices > 0) ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false); /* AFTER ROW UPDATE Triggers */ ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple); } static const char * ExecRelCheck(ResultRelInfo *resultRelInfo, TupleTableSlot *slot, EState *estate) { Relation rel = resultRelInfo->ri_RelationDesc; int ncheck = rel->rd_att->constr->num_check; ConstrCheck *check = rel->rd_att->constr->check; ExprContext *econtext; MemoryContext oldContext; List *qual; int i; /* * If first time through for this result relation, build expression * nodetrees for rel's constraint expressions. Keep them in the * per-query memory context so they'll survive throughout the query. */ if (resultRelInfo->ri_ConstraintExprs == NULL) { oldContext = MemoryContextSwitchTo(estate->es_query_cxt); resultRelInfo->ri_ConstraintExprs = (List **) palloc(ncheck * sizeof(List *)); for (i = 0; i < ncheck; i++) { qual = (List *) stringToNode(check[i].ccbin); resultRelInfo->ri_ConstraintExprs[i] = (List *) ExecPrepareExpr((Expr *) qual, estate); } MemoryContextSwitchTo(oldContext); } /* * We will use the EState's per-tuple context for evaluating * constraint expressions (creating it if it's not already there). */ econtext = GetPerTupleExprContext(estate); /* Arrange for econtext's scan tuple to be the tuple under test */ econtext->ecxt_scantuple = slot; /* And evaluate the constraints */ for (i = 0; i < ncheck; i++) { qual = resultRelInfo->ri_ConstraintExprs[i]; /* * NOTE: SQL92 specifies that a NULL result from a constraint * expression is not to be treated as a failure. Therefore, tell * ExecQual to return TRUE for NULL. */ if (!ExecQual(qual, econtext, true)) return check[i].ccname; } /* NULL result means no error */ return NULL; } void ExecConstraints(ResultRelInfo *resultRelInfo, TupleTableSlot *slot, EState *estate) { Relation rel = resultRelInfo->ri_RelationDesc; HeapTuple tuple = slot->val; TupleConstr *constr = rel->rd_att->constr; Assert(constr); if (constr->has_not_null) { int natts = rel->rd_att->natts; int attrChk; for (attrChk = 1; attrChk <= natts; attrChk++) { if (rel->rd_att->attrs[attrChk - 1]->attnotnull && heap_attisnull(tuple, attrChk)) ereport(ERROR, (errcode(ERRCODE_NOT_NULL_VIOLATION), errmsg("null value in column \"%s\" violates not-null constraint", NameStr(rel->rd_att->attrs[attrChk - 1]->attname)))); } } if (constr->num_check > 0) { const char *failed; if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL) ereport(ERROR, (errcode(ERRCODE_CHECK_VIOLATION), errmsg("new row for relation \"%s\" violates check constraint \"%s\"", RelationGetRelationName(rel), failed))); } } /* * Check a modified tuple to see if we want to process its updated version * under READ COMMITTED rules. * * See backend/executor/README for some info about how this works. */ TupleTableSlot * EvalPlanQual(EState *estate, Index rti, ItemPointer tid) { evalPlanQual *epq; EState *epqstate; Relation relation; HeapTupleData tuple; HeapTuple copyTuple = NULL; bool endNode; Assert(rti != 0); /* * find relation containing target tuple */ if (estate->es_result_relation_info != NULL && estate->es_result_relation_info->ri_RangeTableIndex == rti) relation = estate->es_result_relation_info->ri_RelationDesc; else { List *l; relation = NULL; foreach(l, estate->es_rowMark) { if (((execRowMark *) lfirst(l))->rti == rti) { relation = ((execRowMark *) lfirst(l))->relation; break; } } if (relation == NULL) elog(ERROR, "could not find RowMark for RT index %u", rti); } /* * fetch tid tuple * * Loop here to deal with updated or busy tuples */ tuple.t_self = *tid; for (;;) { Buffer buffer; if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL)) { TransactionId xwait = SnapshotDirty->xmax; /* xmin should not be dirty... */ if (TransactionIdIsValid(SnapshotDirty->xmin)) elog(ERROR, "t_xmin is uncommitted in tuple to be updated"); /* * If tuple is being updated by other transaction then we have * to wait for its commit/abort. */ if (TransactionIdIsValid(xwait)) { ReleaseBuffer(buffer); XactLockTableWait(xwait); continue; } /* * We got tuple - now copy it for use by recheck query. */ copyTuple = heap_copytuple(&tuple); ReleaseBuffer(buffer); break; } /* * Oops! Invalid tuple. Have to check is it updated or deleted. * Note that it's possible to get invalid SnapshotDirty->tid if * tuple updated by this transaction. Have we to check this ? */ if (ItemPointerIsValid(&(SnapshotDirty->tid)) && !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid)))) { /* updated, so look at the updated copy */ tuple.t_self = SnapshotDirty->tid; continue; } /* * Deleted or updated by this transaction; forget it. */ return NULL; } /* * For UPDATE/DELETE we have to return tid of actual row we're * executing PQ for. */ *tid = tuple.t_self; /* * Need to run a recheck subquery. Find or create a PQ stack entry. */ epq = estate->es_evalPlanQual; endNode = true; if (epq != NULL && epq->rti == 0) { /* Top PQ stack entry is idle, so re-use it */ Assert(!(estate->es_useEvalPlan) && epq->next == NULL); epq->rti = rti; endNode = false; } /* * If this is request for another RTE - Ra, - then we have to check * wasn't PlanQual requested for Ra already and if so then Ra' row was * updated again and we have to re-start old execution for Ra and * forget all what we done after Ra was suspended. Cool? -:)) */ if (epq != NULL && epq->rti != rti && epq->estate->es_evTuple[rti - 1] != NULL) { do { evalPlanQual *oldepq; /* stop execution */ EvalPlanQualStop(epq); /* pop previous PlanQual from the stack */ oldepq = epq->next; Assert(oldepq && oldepq->rti != 0); /* push current PQ to freePQ stack */ oldepq->free = epq; epq = oldepq; estate->es_evalPlanQual = epq; } while (epq->rti != rti); } /* * If we are requested for another RTE then we have to suspend * execution of current PlanQual and start execution for new one. */ if (epq == NULL || epq->rti != rti) { /* try to reuse plan used previously */ evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL; if (newepq == NULL) /* first call or freePQ stack is empty */ { newepq = (evalPlanQual *) palloc0(sizeof(evalPlanQual)); newepq->free = NULL; newepq->estate = NULL; newepq->planstate = NULL; } else { /* recycle previously used PlanQual */ Assert(newepq->estate == NULL); epq->free = NULL; } /* push current PQ to the stack */ newepq->next = epq; epq = newepq; estate->es_evalPlanQual = epq; epq->rti = rti; endNode = false; } Assert(epq->rti == rti); /* * Ok - we're requested for the same RTE. Unfortunately we still have * to end and restart execution of the plan, because ExecReScan * wouldn't ensure that upper plan nodes would reset themselves. We * could make that work if insertion of the target tuple were * integrated with the Param mechanism somehow, so that the upper plan * nodes know that their children's outputs have changed. * * Note that the stack of free evalPlanQual nodes is quite useless at the * moment, since it only saves us from pallocing/releasing the * evalPlanQual nodes themselves. But it will be useful once we * implement ReScan instead of end/restart for re-using PlanQual * nodes. */ if (endNode) { /* stop execution */ EvalPlanQualStop(epq); } /* * Initialize new recheck query. * * Note: if we were re-using PlanQual plans via ExecReScan, we'd need to * instead copy down changeable state from the top plan (including * es_result_relation_info, es_junkFilter) and reset locally * changeable state in the epq (including es_param_exec_vals, * es_evTupleNull). */ EvalPlanQualStart(epq, estate, epq->next); /* * free old RTE' tuple, if any, and store target tuple where * relation's scan node will see it */ epqstate = epq->estate; if (epqstate->es_evTuple[rti - 1] != NULL) heap_freetuple(epqstate->es_evTuple[rti - 1]); epqstate->es_evTuple[rti - 1] = copyTuple; return EvalPlanQualNext(estate); } static TupleTableSlot * EvalPlanQualNext(EState *estate) { evalPlanQual *epq = estate->es_evalPlanQual; MemoryContext oldcontext; TupleTableSlot *slot; Assert(epq->rti != 0); lpqnext:; oldcontext = MemoryContextSwitchTo(epq->estate->es_query_cxt); slot = ExecProcNode(epq->planstate); MemoryContextSwitchTo(oldcontext); /* * No more tuples for this PQ. Continue previous one. */ if (TupIsNull(slot)) { evalPlanQual *oldepq; /* stop execution */ EvalPlanQualStop(epq); /* pop old PQ from the stack */ oldepq = epq->next; if (oldepq == NULL) { /* this is the first (oldest) PQ - mark as free */ epq->rti = 0; estate->es_useEvalPlan = false; /* and continue Query execution */ return (NULL); } Assert(oldepq->rti != 0); /* push current PQ to freePQ stack */ oldepq->free = epq; epq = oldepq; estate->es_evalPlanQual = epq; goto lpqnext; } return (slot); } static void EndEvalPlanQual(EState *estate) { evalPlanQual *epq = estate->es_evalPlanQual; if (epq->rti == 0) /* plans already shutdowned */ { Assert(epq->next == NULL); return; } for (;;) { evalPlanQual *oldepq; /* stop execution */ EvalPlanQualStop(epq); /* pop old PQ from the stack */ oldepq = epq->next; if (oldepq == NULL) { /* this is the first (oldest) PQ - mark as free */ epq->rti = 0; estate->es_useEvalPlan = false; break; } Assert(oldepq->rti != 0); /* push current PQ to freePQ stack */ oldepq->free = epq; epq = oldepq; estate->es_evalPlanQual = epq; } } /* * Start execution of one level of PlanQual. * * This is a cut-down version of ExecutorStart(): we copy some state from * the top-level estate rather than initializing it fresh. */ static void EvalPlanQualStart(evalPlanQual *epq, EState *estate, evalPlanQual *priorepq) { EState *epqstate; int rtsize; MemoryContext oldcontext; rtsize = length(estate->es_range_table); epq->estate = epqstate = CreateExecutorState(); oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt); /* * The epqstates share the top query's copy of unchanging state such * as the snapshot, rangetable, result-rel info, and external Param * info. They need their own copies of local state, including a tuple * table, es_param_exec_vals, etc. */ epqstate->es_direction = ForwardScanDirection; epqstate->es_snapshot = estate->es_snapshot; epqstate->es_crosscheck_snapshot = estate->es_crosscheck_snapshot; epqstate->es_range_table = estate->es_range_table; epqstate->es_result_relations = estate->es_result_relations; epqstate->es_num_result_relations = estate->es_num_result_relations; epqstate->es_result_relation_info = estate->es_result_relation_info; epqstate->es_junkFilter = estate->es_junkFilter; epqstate->es_into_relation_descriptor = estate->es_into_relation_descriptor; epqstate->es_param_list_info = estate->es_param_list_info; if (estate->es_topPlan->nParamExec > 0) epqstate->es_param_exec_vals = (ParamExecData *) palloc0(estate->es_topPlan->nParamExec * sizeof(ParamExecData)); epqstate->es_rowMark = estate->es_rowMark; epqstate->es_instrument = estate->es_instrument; epqstate->es_force_oids = estate->es_force_oids; epqstate->es_topPlan = estate->es_topPlan; /* * Each epqstate must have its own es_evTupleNull state, but all the * stack entries share es_evTuple state. This allows sub-rechecks to * inherit the value being examined by an outer recheck. */ epqstate->es_evTupleNull = (bool *) palloc0(rtsize * sizeof(bool)); if (priorepq == NULL) /* first PQ stack entry */ epqstate->es_evTuple = (HeapTuple *) palloc0(rtsize * sizeof(HeapTuple)); else /* later stack entries share the same storage */ epqstate->es_evTuple = priorepq->estate->es_evTuple; epqstate->es_tupleTable = ExecCreateTupleTable(estate->es_tupleTable->size); epq->planstate = ExecInitNode(estate->es_topPlan, epqstate); MemoryContextSwitchTo(oldcontext); } /* * End execution of one level of PlanQual. * * This is a cut-down version of ExecutorEnd(); basically we want to do most * of the normal cleanup, but *not* close result relations (which we are * just sharing from the outer query). */ static void EvalPlanQualStop(evalPlanQual *epq) { EState *epqstate = epq->estate; MemoryContext oldcontext; oldcontext = MemoryContextSwitchTo(epqstate->es_query_cxt); ExecEndNode(epq->planstate); ExecDropTupleTable(epqstate->es_tupleTable, true); epqstate->es_tupleTable = NULL; if (epqstate->es_evTuple[epq->rti - 1] != NULL) { heap_freetuple(epqstate->es_evTuple[epq->rti - 1]); epqstate->es_evTuple[epq->rti - 1] = NULL; } MemoryContextSwitchTo(oldcontext); FreeExecutorState(epqstate); epq->estate = NULL; epq->planstate = NULL; }