/*------------------------------------------------------------------------- * * 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routines * * INTERFACE ROUTINES * ExecutorStart() * ExecutorRun() * ExecutorEnd() * * The old ExecutorMain() has been replaced by ExecutorStart(), * ExecutorRun() and ExecutorEnd() * * These three procedures are the external interfaces to the executor.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 and the execution state is required * as arguments * * ExecutorStart() must be called at the beginning of any 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) 1996-2001, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.157 2002/04/08 22:42:18 momjian Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/heapam.h" #include "catalog/heap.h" #include "catalog/namespace.h" #include "commands/command.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" /* decls for local routines only used within this module */ static TupleDesc InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate); static void initResultRelInfo(ResultRelInfo *resultRelInfo, Index resultRelationIndex, List *rangeTable, CmdType operation); static void EndPlan(Plan *plan, EState *estate); static TupleTableSlot *ExecutePlan(EState *estate, Plan *plan, CmdType operation, long numberTuples, ScanDirection direction, DestReceiver *destfunc); static void ExecRetrieve(TupleTableSlot *slot, DestReceiver *destfunc, EState *estate); static void ExecAppend(TupleTableSlot *slot, ItemPointer tupleid, EState *estate); static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid, EState *estate); static void ExecReplace(TupleTableSlot *slot, ItemPointer tupleid, EState *estate); static TupleTableSlot *EvalPlanQualNext(EState *estate); static void EndEvalPlanQual(EState *estate); static void ExecCheckQueryPerms(CmdType operation, Query *parseTree, Plan *plan); static void ExecCheckPlanPerms(Plan *plan, List *rangeTable, CmdType operation); static void ExecCheckRTPerms(List *rangeTable, CmdType operation); static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation); /* end of local decls */ /* ---------------------------------------------------------------- * ExecutorStart * * This routine must be called at the beginning of any execution of any * query plan * * returns a TupleDesc which describes the attributes of the tuples to * be returned by the query. (Same value is saved in queryDesc) * * NB: the CurrentMemoryContext when this is called must be the context * to be used as the per-query context for the query plan. ExecutorRun() * and ExecutorEnd() must be called in this same memory context. * ---------------------------------------------------------------- */ TupleDesc ExecutorStart(QueryDesc *queryDesc, EState *estate) { TupleDesc result; /* sanity checks */ Assert(queryDesc != NULL); if (queryDesc->plantree->nParamExec > 0) { estate->es_param_exec_vals = (ParamExecData *) palloc(queryDesc->plantree->nParamExec * sizeof(ParamExecData)); MemSet(estate->es_param_exec_vals, 0, queryDesc->plantree->nParamExec * sizeof(ParamExecData)); } /* * Make our own private copy of the current queries snapshot data */ if (QuerySnapshot == NULL) estate->es_snapshot = NULL; else { estate->es_snapshot = (Snapshot) palloc(sizeof(SnapshotData)); memcpy(estate->es_snapshot, QuerySnapshot, sizeof(SnapshotData)); if (estate->es_snapshot->xcnt > 0) { estate->es_snapshot->xip = (TransactionId *) palloc(estate->es_snapshot->xcnt * sizeof(TransactionId)); memcpy(estate->es_snapshot->xip, QuerySnapshot->xip, estate->es_snapshot->xcnt * sizeof(TransactionId)); } } /* * Initialize the plan */ result = InitPlan(queryDesc->operation, queryDesc->parsetree, queryDesc->plantree, estate); queryDesc->tupDesc = result; return result; } /* ---------------------------------------------------------------- * 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, e.g. run to * completion. * * ---------------------------------------------------------------- */ TupleTableSlot * ExecutorRun(QueryDesc *queryDesc, EState *estate, ScanDirection direction, long count) { CmdType operation; Plan *plan; CommandDest dest; DestReceiver *destfunc; TupleTableSlot *result; /* * sanity checks */ Assert(queryDesc != NULL); /* * extract information from the query descriptor and the query * feature. */ operation = queryDesc->operation; plan = queryDesc->plantree; dest = queryDesc->dest; /* * startup tuple receiver */ estate->es_processed = 0; estate->es_lastoid = InvalidOid; destfunc = DestToFunction(dest); (*destfunc->setup) (destfunc, (int) operation, queryDesc->portalName, queryDesc->tupDesc); /* * run plan */ if (direction == NoMovementScanDirection) result = NULL; else result = ExecutePlan(estate, plan, operation, count, direction, destfunc); /* * shutdown receiver */ (*destfunc->cleanup) (destfunc); return result; } /* ---------------------------------------------------------------- * ExecutorEnd * * This routine must be called at the end of execution of any * query plan * ---------------------------------------------------------------- */ void ExecutorEnd(QueryDesc *queryDesc, EState *estate) { /* sanity checks */ Assert(queryDesc != NULL); EndPlan(queryDesc->plantree, estate); if (estate->es_snapshot != NULL) { if (estate->es_snapshot->xcnt > 0) pfree(estate->es_snapshot->xip); pfree(estate->es_snapshot); estate->es_snapshot = NULL; } if (estate->es_param_exec_vals != NULL) { pfree(estate->es_param_exec_vals); estate->es_param_exec_vals = NULL; } } /* * ExecCheckQueryPerms * Check access permissions for all relations referenced in a query. */ static void ExecCheckQueryPerms(CmdType operation, Query *parseTree, Plan *plan) { /* * Check RTEs in the query's primary rangetable. */ ExecCheckRTPerms(parseTree->rtable, operation); /* * Search for subplans and APPEND nodes to check their rangetables. */ ExecCheckPlanPerms(plan, parseTree->rtable, operation); } /* * ExecCheckPlanPerms * Recursively scan the plan tree to check access permissions in * subplans. */ static void ExecCheckPlanPerms(Plan *plan, List *rangeTable, CmdType operation) { List *subp; if (plan == NULL) return; /* Check subplans, which we assume are plain SELECT queries */ foreach(subp, plan->initPlan) { SubPlan *subplan = (SubPlan *) lfirst(subp); ExecCheckRTPerms(subplan->rtable, CMD_SELECT); ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT); } foreach(subp, plan->subPlan) { SubPlan *subplan = (SubPlan *) lfirst(subp); ExecCheckRTPerms(subplan->rtable, CMD_SELECT); ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT); } /* Check lower plan nodes */ ExecCheckPlanPerms(plan->lefttree, rangeTable, operation); ExecCheckPlanPerms(plan->righttree, rangeTable, operation); /* Do node-type-specific checks */ switch (nodeTag(plan)) { case T_SubqueryScan: { SubqueryScan *scan = (SubqueryScan *) plan; RangeTblEntry *rte; /* Recursively check the subquery */ rte = rt_fetch(scan->scan.scanrelid, rangeTable); Assert(rte->subquery != NULL); ExecCheckQueryPerms(operation, rte->subquery, scan->subplan); break; } case T_Append: { Append *app = (Append *) plan; List *appendplans; foreach(appendplans, app->appendplans) { ExecCheckPlanPerms((Plan *) lfirst(appendplans), rangeTable, operation); } break; } default: break; } } /* * ExecCheckRTPerms * Check access permissions for all relations listed in a range table. */ static 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; Oid userid; int32 aclcheck_result; /* * If it's a subquery RTE, ignore it --- it will be checked when * ExecCheckPlanPerms finds the SubqueryScan node for it. */ 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 ExecCheckQueryPerms 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) elog(ERROR, "%s: %s", get_rel_name(relOid), aclcheck_error_strings[aclcheck_result]); } 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, "ExecCheckRTEPerms: bogus operation %d", operation); aclcheck_result = ACLCHECK_OK; /* keep compiler quiet */ break; } if (aclcheck_result != ACLCHECK_OK) elog(ERROR, "%s: %s", get_rel_name(relOid), aclcheck_error_strings[aclcheck_result]); } } /* =============================================================== * =============================================================== static routines follow * =============================================================== * =============================================================== */ typedef struct execRowMark { Relation relation; Index rti; char resname[32]; } execRowMark; typedef struct evalPlanQual { Plan *plan; Index rti; EState estate; struct evalPlanQual *free; } evalPlanQual; /* ---------------------------------------------------------------- * InitPlan * * Initializes the query plan: open files, allocate storage * and start up the rule manager * ---------------------------------------------------------------- */ static TupleDesc InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate) { List *rangeTable; Relation intoRelationDesc; TupleDesc tupType; /* * Do permissions checks. */ ExecCheckQueryPerms(operation, parseTree, plan); /* * 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; } /* * 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; sprintf(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_origPlan = plan; estate->es_evalPlanQual = NULL; estate->es_evTuple = NULL; estate->es_evTupleNull = 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. */ ExecInitNode(plan, estate, NULL); /* * Get the tuple descriptor describing the type of tuples to return. * (this is especially important if we are creating a relation with * "retrieve into") */ tupType = ExecGetTupType(plan); /* tuple descriptor */ /* * Initialize the junk filter if needed. SELECT and INSERT queries * need a filter if there are any junk attrs in the tlist. UPDATE and * DELETE always need one, 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; } } 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) { List *subplans; ResultRelInfo *resultRelInfo; /* Top plan had better be an Append here. */ Assert(IsA(plan, Append)); Assert(((Append *) plan)->isTarget); subplans = ((Append *) plan)->appendplans; Assert(length(subplans) == estate->es_num_result_relations); resultRelInfo = estate->es_result_relations; while (subplans != NIL) { Plan *subplan = (Plan *) lfirst(subplans); JunkFilter *j; j = ExecInitJunkFilter(subplan->targetlist, ExecGetTupType(subplan), ExecAllocTableSlot(estate->es_tupleTable)); resultRelInfo->ri_junkFilter = j; resultRelInfo++; subplans = lnext(subplans); } /* * 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(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; } /* * initialize the "into" relation */ intoRelationDesc = (Relation) NULL; if (operation == CMD_SELECT) { if (!parseTree->isPortal) { /* * a select into table */ if (parseTree->into != NULL) { char *intoName; Oid namespaceId; Oid intoRelationId; TupleDesc tupdesc; /* * create the "into" relation */ intoName = parseTree->into->relname; namespaceId = RangeVarGetCreationNamespace(parseTree->into); /* * have to copy tupType to get rid of constraints */ tupdesc = CreateTupleDescCopy(tupType); intoRelationId = heap_create_with_catalog(intoName, namespaceId, tupdesc, RELKIND_RELATION, true, 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); intoRelationDesc = heap_open(intoRelationId, AccessExclusiveLock); } } } estate->es_into_relation_descriptor = intoRelationDesc; return tupType; } /* * 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: elog(ERROR, "You can't change sequence relation %s", RelationGetRelationName(resultRelationDesc)); break; case RELKIND_TOASTVALUE: elog(ERROR, "You can't change toast relation %s", RelationGetRelationName(resultRelationDesc)); break; case RELKIND_VIEW: elog(ERROR, "You can't change view relation %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; resultRelInfo->ri_TrigDesc = 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); } /* ---------------------------------------------------------------- * EndPlan * * Cleans up the query plan -- closes files and free up storages * ---------------------------------------------------------------- */ static void EndPlan(Plan *plan, 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(plan, NULL); /* * 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. Also clean up junkfilters if present. */ 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); /* Delete the junkfilter if any */ if (resultRelInfo->ri_junkFilter != NULL) ExecFreeJunkFilter(resultRelInfo->ri_junkFilter); 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); /* * There might be a junkfilter without a result relation. */ if (estate->es_num_result_relations == 0 && estate->es_junkFilter != NULL) { ExecFreeJunkFilter(estate->es_junkFilter); estate->es_junkFilter = NULL; } /* * 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 RETRIEVE 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, Plan *plan, CmdType operation, long numberTuples, ScanDirection direction, DestReceiver *destfunc) { 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; /* * 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(plan, NULL); } else slot = ExecProcNode(plan, NULL); /* * 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, "ExecutePlan: NO (junk) `ctid' was found!"); /* shouldn't ever get a null result... */ if (isNull) elog(ERROR, "ExecutePlan: (junk) `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, "ExecutePlan: NO (junk) `%s' was found!", erm->resname); /* shouldn't ever get a null result... */ if (isNull) elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!", erm->resname); tuple.t_self = *((ItemPointer) DatumGetPointer(datum)); test = heap_mark4update(erm->relation, &tuple, &buffer); ReleaseBuffer(buffer); switch (test) { case HeapTupleSelfUpdated: case HeapTupleMayBeUpdated: break; case HeapTupleUpdated: if (XactIsoLevel == XACT_SERIALIZABLE) elog(ERROR, "Can't 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, "Unknown status %u from heap_mark4update", 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 */ } /* if (junkfilter... */ /* * 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: ExecRetrieve(slot, /* slot containing tuple */ destfunc, /* destination's tuple-receiver * obj */ estate); /* */ result = slot; break; case CMD_INSERT: ExecAppend(slot, tupleid, estate); result = NULL; break; case CMD_DELETE: ExecDelete(slot, tupleid, estate); result = NULL; break; case CMD_UPDATE: ExecReplace(slot, tupleid, estate); result = NULL; break; default: elog(LOG, "ExecutePlan: unknown operation in queryDesc"); result = NULL; break; } /* * check our tuple count.. if we've processed the proper number * then quit, else loop again and process more tuples.. */ current_tuple_count++; if (numberTuples == current_tuple_count) break; } /* * here, result is either a slot containing a tuple in the case of a * RETRIEVE or NULL otherwise. */ return result; } /* ---------------------------------------------------------------- * ExecRetrieve * * RETRIEVEs are easy.. we just pass the tuple to the appropriate * print function. The only complexity is when we do a * "retrieve 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 ExecRetrieve(TupleTableSlot *slot, DestReceiver *destfunc, 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" */ if (estate->es_into_relation_descriptor != NULL) { heap_insert(estate->es_into_relation_descriptor, tuple); IncrAppended(); } /* * send the tuple to the front end (or the screen) */ (*destfunc->receiveTuple) (tuple, attrtype, destfunc); IncrRetrieved(); (estate->es_processed)++; } /* ---------------------------------------------------------------- * ExecAppend * * APPENDs are trickier.. we have to insert the tuple into * the base relation and insert appropriate tuples into the * index relations. * ---------------------------------------------------------------- */ static void ExecAppend(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("ExecAppend", resultRelInfo, slot, estate); /* * insert the tuple */ newId = heap_insert(resultRelationDesc, tuple); 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 */ if (resultRelInfo->ri_TrigDesc) ExecARInsertTriggers(estate, resultRelInfo, tuple); } /* ---------------------------------------------------------------- * ExecDelete * * DELETE is like append, 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); if (!dodelete) /* "do nothing" */ return; } /* * delete the tuple */ ldelete:; result = heap_delete(resultRelationDesc, tupleid, &ctid); switch (result) { case HeapTupleSelfUpdated: return; case HeapTupleMayBeUpdated: break; case HeapTupleUpdated: if (XactIsoLevel == XACT_SERIALIZABLE) elog(ERROR, "Can't 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, "Unknown status %u from heap_delete", 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 */ if (resultRelInfo->ri_TrigDesc) ExecARDeleteTriggers(estate, resultRelInfo, tupleid); } /* ---------------------------------------------------------------- * ExecReplace * * note: we can't run replace queries with transactions * off because replaces are actually appends and our * scan will mistakenly loop forever, replacing the tuple * it just appended.. 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 ExecReplace(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(WARNING, "ExecReplace: replace can't run without transactions"); return; } /* * 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); 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("ExecReplace", resultRelInfo, slot, estate); /* * replace the heap tuple */ result = heap_update(resultRelationDesc, tupleid, tuple, &ctid); switch (result) { case HeapTupleSelfUpdated: return; case HeapTupleMayBeUpdated: break; case HeapTupleUpdated: if (XactIsoLevel == XACT_SERIALIZABLE) elog(ERROR, "Can't 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, "Unknown status %u from heap_update", 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 replaces 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 appending 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, true); /* AFTER ROW UPDATE Triggers */ if (resultRelInfo->ri_TrigDesc) ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple); } static 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] = qual; } 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 (char *) NULL; } void ExecConstraints(char *caller, 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)) elog(ERROR, "%s: Fail to add null value in not null attribute %s", caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname)); } } if (constr->num_check > 0) { char *failed; if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL) elog(ERROR, "%s: rejected due to CHECK constraint %s", caller, 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; int rtsize; 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, "EvalPlanQual: can't find RTE %d", (int) rti); } /* * fetch tid tuple * * Loop here to deal with updated or busy tuples */ tuple.t_self = *tid; for (;;) { Buffer buffer; heap_fetch(relation, SnapshotDirty, &tuple, &buffer, NULL); if (tuple.t_data != NULL) { TransactionId xwait = SnapshotDirty->xmax; if (TransactionIdIsValid(SnapshotDirty->xmin)) elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!"); /* * 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 = (evalPlanQual *) estate->es_evalPlanQual; rtsize = length(estate->es_range_table); endNode = true; if (epq != NULL && epq->rti == 0) { /* Top PQ stack entry is idle, so re-use it */ Assert(!(estate->es_useEvalPlan) && epq->estate.es_evalPlanQual == 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; /* pop previous PlanQual from the stack */ epqstate = &(epq->estate); oldepq = (evalPlanQual *) epqstate->es_evalPlanQual; Assert(oldepq->rti != 0); /* stop execution */ ExecEndNode(epq->plan, NULL); ExecDropTupleTable(epqstate->es_tupleTable, true); epqstate->es_tupleTable = NULL; heap_freetuple(epqstate->es_evTuple[epq->rti - 1]); epqstate->es_evTuple[epq->rti - 1] = NULL; /* push current PQ to freePQ stack */ oldepq->free = epq; epq = oldepq; estate->es_evalPlanQual = (Pointer) 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 *) palloc(sizeof(evalPlanQual)); newepq->free = NULL; /* * Each stack level has its own copy of the plan tree. This * is wasteful, but necessary as long as plan nodes point to * exec state nodes rather than vice versa. Note that * copyfuncs.c doesn't attempt to copy the exec state nodes, * which is a good thing in this situation. */ newepq->plan = copyObject(estate->es_origPlan); /* * Init stack level's EState. We share top level's copy of * es_result_relations array and other non-changing status. We * need our own tupletable, es_param_exec_vals, and other * changeable state. */ epqstate = &(newepq->estate); memcpy(epqstate, estate, sizeof(EState)); epqstate->es_direction = ForwardScanDirection; if (estate->es_origPlan->nParamExec > 0) epqstate->es_param_exec_vals = (ParamExecData *) palloc(estate->es_origPlan->nParamExec * sizeof(ParamExecData)); epqstate->es_tupleTable = NULL; epqstate->es_per_tuple_exprcontext = NULL; /* * 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 *) palloc(rtsize * sizeof(bool)); if (epq == NULL) { /* first PQ stack entry */ epqstate->es_evTuple = (HeapTuple *) palloc(rtsize * sizeof(HeapTuple)); memset(epqstate->es_evTuple, 0, rtsize * sizeof(HeapTuple)); } else { /* later stack entries share the same storage */ epqstate->es_evTuple = epq->estate.es_evTuple; } } else { /* recycle previously used EState */ epqstate = &(newepq->estate); } /* push current PQ to the stack */ epqstate->es_evalPlanQual = (Pointer) epq; epq = newepq; estate->es_evalPlanQual = (Pointer) epq; epq->rti = rti; endNode = false; } Assert(epq->rti == rti); epqstate = &(epq->estate); /* * 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. */ if (endNode) { /* stop execution */ ExecEndNode(epq->plan, NULL); ExecDropTupleTable(epqstate->es_tupleTable, true); epqstate->es_tupleTable = NULL; } /* * free old RTE' tuple, if any, and store target tuple where * relation's scan node will see it */ if (epqstate->es_evTuple[rti - 1] != NULL) heap_freetuple(epqstate->es_evTuple[rti - 1]); epqstate->es_evTuple[rti - 1] = copyTuple; /* * Initialize for new recheck query; be careful to copy down state * that might have changed in top EState. */ epqstate->es_result_relation_info = estate->es_result_relation_info; epqstate->es_junkFilter = estate->es_junkFilter; if (estate->es_origPlan->nParamExec > 0) memset(epqstate->es_param_exec_vals, 0, estate->es_origPlan->nParamExec * sizeof(ParamExecData)); memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool)); epqstate->es_useEvalPlan = false; Assert(epqstate->es_tupleTable == NULL); epqstate->es_tupleTable = ExecCreateTupleTable(estate->es_tupleTable->size); ExecInitNode(epq->plan, epqstate, NULL); return EvalPlanQualNext(estate); } static TupleTableSlot * EvalPlanQualNext(EState *estate) { evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual; EState *epqstate = &(epq->estate); evalPlanQual *oldepq; TupleTableSlot *slot; Assert(epq->rti != 0); lpqnext:; slot = ExecProcNode(epq->plan, NULL); /* * No more tuples for this PQ. Continue previous one. */ if (TupIsNull(slot)) { /* stop execution */ ExecEndNode(epq->plan, NULL); ExecDropTupleTable(epqstate->es_tupleTable, true); epqstate->es_tupleTable = NULL; heap_freetuple(epqstate->es_evTuple[epq->rti - 1]); epqstate->es_evTuple[epq->rti - 1] = NULL; /* pop old PQ from the stack */ oldepq = (evalPlanQual *) epqstate->es_evalPlanQual; if (oldepq == (evalPlanQual *) NULL) { epq->rti = 0; /* this is the first (oldest) */ estate->es_useEvalPlan = false; /* PQ - mark as free and */ return (NULL); /* continue Query execution */ } Assert(oldepq->rti != 0); /* push current PQ to freePQ stack */ oldepq->free = epq; epq = oldepq; epqstate = &(epq->estate); estate->es_evalPlanQual = (Pointer) epq; goto lpqnext; } return (slot); } static void EndEvalPlanQual(EState *estate) { evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual; EState *epqstate = &(epq->estate); evalPlanQual *oldepq; if (epq->rti == 0) /* plans already shutdowned */ { Assert(epq->estate.es_evalPlanQual == NULL); return; } for (;;) { /* stop execution */ ExecEndNode(epq->plan, NULL); 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; } /* pop old PQ from the stack */ oldepq = (evalPlanQual *) epqstate->es_evalPlanQual; if (oldepq == (evalPlanQual *) NULL) { epq->rti = 0; /* this is the first (oldest) */ estate->es_useEvalPlan = false; /* PQ - mark as free */ break; } Assert(oldepq->rti != 0); /* push current PQ to freePQ stack */ oldepq->free = epq; epq = oldepq; epqstate = &(epq->estate); estate->es_evalPlanQual = (Pointer) epq; } }