1 /*-------------------------------------------------------------------------
4 * top level executor interface routines
11 * The old ExecutorMain() has been replaced by ExecutorStart(),
12 * ExecutorRun() and ExecutorEnd()
14 * These three procedures are the external interfaces to the executor.
15 * In each case, the query descriptor and the execution state is required
18 * ExecutorStart() must be called at the beginning of any execution of any
19 * query plan and ExecutorEnd() should always be called at the end of
20 * execution of a plan.
22 * ExecutorRun accepts 'feature' and 'count' arguments that specify whether
23 * the plan is to be executed forwards, backwards, and for how many tuples.
25 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
26 * Portions Copyright (c) 1994, Regents of the University of California
30 * $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.144 2001/06/22 19:16:22 wieck Exp $
32 *-------------------------------------------------------------------------
36 #include "access/heapam.h"
37 #include "catalog/heap.h"
38 #include "commands/command.h"
39 #include "commands/trigger.h"
40 #include "executor/execdebug.h"
41 #include "executor/execdefs.h"
42 #include "miscadmin.h"
43 #include "optimizer/var.h"
44 #include "parser/parsetree.h"
45 #include "utils/acl.h"
48 /* decls for local routines only used within this module */
49 static TupleDesc InitPlan(CmdType operation,
53 static void initResultRelInfo(ResultRelInfo *resultRelInfo,
54 Index resultRelationIndex,
57 static void EndPlan(Plan *plan, EState *estate);
58 static TupleTableSlot *ExecutePlan(EState *estate, Plan *plan,
61 ScanDirection direction,
62 DestReceiver *destfunc);
63 static void ExecRetrieve(TupleTableSlot *slot,
64 DestReceiver *destfunc,
66 static void ExecAppend(TupleTableSlot *slot, ItemPointer tupleid,
68 static void ExecDelete(TupleTableSlot *slot, ItemPointer tupleid,
70 static void ExecReplace(TupleTableSlot *slot, ItemPointer tupleid,
72 static TupleTableSlot *EvalPlanQualNext(EState *estate);
73 static void EndEvalPlanQual(EState *estate);
74 static void ExecCheckQueryPerms(CmdType operation, Query *parseTree,
76 static void ExecCheckPlanPerms(Plan *plan, List *rangeTable,
78 static void ExecCheckRTPerms(List *rangeTable, CmdType operation);
79 static void ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation);
81 /* end of local decls */
84 /* ----------------------------------------------------------------
87 * This routine must be called at the beginning of any execution of any
90 * returns a TupleDesc which describes the attributes of the tuples to
91 * be returned by the query.
93 * NB: the CurrentMemoryContext when this is called must be the context
94 * to be used as the per-query context for the query plan. ExecutorRun()
95 * and ExecutorEnd() must be called in this same memory context.
96 * ----------------------------------------------------------------
99 ExecutorStart(QueryDesc *queryDesc, EState *estate)
104 Assert(queryDesc != NULL);
106 if (queryDesc->plantree->nParamExec > 0)
108 estate->es_param_exec_vals = (ParamExecData *)
109 palloc(queryDesc->plantree->nParamExec * sizeof(ParamExecData));
110 MemSet(estate->es_param_exec_vals, 0,
111 queryDesc->plantree->nParamExec * sizeof(ParamExecData));
115 * Make our own private copy of the current queries snapshot data
117 if (QuerySnapshot == NULL)
118 estate->es_snapshot = NULL;
121 estate->es_snapshot = (Snapshot) palloc(sizeof(SnapshotData));
122 memcpy(estate->es_snapshot, QuerySnapshot, sizeof(SnapshotData));
123 if (estate->es_snapshot->xcnt > 0)
125 estate->es_snapshot->xip = (TransactionId *)
126 palloc(estate->es_snapshot->xcnt * sizeof(TransactionId));
127 memcpy(estate->es_snapshot->xip, QuerySnapshot->xip,
128 estate->es_snapshot->xcnt * sizeof(TransactionId));
133 * Initialize the plan
135 result = InitPlan(queryDesc->operation,
136 queryDesc->parsetree,
143 /* ----------------------------------------------------------------
146 * This is the main routine of the executor module. It accepts
147 * the query descriptor from the traffic cop and executes the
150 * ExecutorStart must have been called already.
152 * the different features supported are:
153 * EXEC_RUN: retrieve all tuples in the forward direction
154 * EXEC_FOR: retrieve 'count' number of tuples in the forward dir
155 * EXEC_BACK: retrieve 'count' number of tuples in the backward dir
156 * EXEC_RETONE: return one tuple but don't 'retrieve' it
157 * used in postquel function processing
159 * Note: count = 0 is interpreted as "no limit".
161 * ----------------------------------------------------------------
164 ExecutorRun(QueryDesc *queryDesc, EState *estate, int feature, long count)
168 TupleTableSlot *result;
170 DestReceiver *destfunc;
175 Assert(queryDesc != NULL);
178 * extract information from the query descriptor and the query
181 operation = queryDesc->operation;
182 plan = queryDesc->plantree;
183 dest = queryDesc->dest;
184 destfunc = DestToFunction(dest);
185 estate->es_processed = 0;
186 estate->es_lastoid = InvalidOid;
189 * FIXME: the dest setup function ought to be handed the tuple desc
190 * for the tuples to be output, but I'm not quite sure how to get that
191 * info at this point. For now, passing NULL is OK because no
192 * existing dest setup function actually uses the pointer.
194 (*destfunc->setup) (destfunc, (TupleDesc) NULL);
199 result = ExecutePlan(estate,
203 ForwardScanDirection,
208 result = ExecutePlan(estate,
212 ForwardScanDirection,
217 * retrieve next n "backward" tuples
220 result = ExecutePlan(estate,
224 BackwardScanDirection,
229 * return one tuple but don't "retrieve" it. (this is used by
230 * the rule manager..) -cim 9/14/89
233 result = ExecutePlan(estate,
237 ForwardScanDirection,
242 elog(DEBUG, "ExecutorRun: Unknown feature %d", feature);
247 (*destfunc->cleanup) (destfunc);
252 /* ----------------------------------------------------------------
255 * This routine must be called at the end of execution of any
257 * ----------------------------------------------------------------
260 ExecutorEnd(QueryDesc *queryDesc, EState *estate)
263 Assert(queryDesc != NULL);
265 EndPlan(queryDesc->plantree, estate);
267 if (estate->es_snapshot != NULL)
269 if (estate->es_snapshot->xcnt > 0)
270 pfree(estate->es_snapshot->xip);
271 pfree(estate->es_snapshot);
272 estate->es_snapshot = NULL;
275 if (estate->es_param_exec_vals != NULL)
277 pfree(estate->es_param_exec_vals);
278 estate->es_param_exec_vals = NULL;
284 * ExecCheckQueryPerms
285 * Check access permissions for all relations referenced in a query.
288 ExecCheckQueryPerms(CmdType operation, Query *parseTree, Plan *plan)
292 * Check RTEs in the query's primary rangetable.
294 ExecCheckRTPerms(parseTree->rtable, operation);
297 * Search for subplans and APPEND nodes to check their rangetables.
299 ExecCheckPlanPerms(plan, parseTree->rtable, operation);
304 * Recursively scan the plan tree to check access permissions in
308 ExecCheckPlanPerms(Plan *plan, List *rangeTable, CmdType operation)
315 /* Check subplans, which we assume are plain SELECT queries */
317 foreach(subp, plan->initPlan)
319 SubPlan *subplan = (SubPlan *) lfirst(subp);
321 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
322 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
324 foreach(subp, plan->subPlan)
326 SubPlan *subplan = (SubPlan *) lfirst(subp);
328 ExecCheckRTPerms(subplan->rtable, CMD_SELECT);
329 ExecCheckPlanPerms(subplan->plan, subplan->rtable, CMD_SELECT);
332 /* Check lower plan nodes */
334 ExecCheckPlanPerms(plan->lefttree, rangeTable, operation);
335 ExecCheckPlanPerms(plan->righttree, rangeTable, operation);
337 /* Do node-type-specific checks */
339 switch (nodeTag(plan))
343 SubqueryScan *scan = (SubqueryScan *) plan;
346 /* Recursively check the subquery */
347 rte = rt_fetch(scan->scan.scanrelid, rangeTable);
348 Assert(rte->subquery != NULL);
349 ExecCheckQueryPerms(operation, rte->subquery, scan->subplan);
354 Append *app = (Append *) plan;
357 foreach(appendplans, app->appendplans)
359 ExecCheckPlanPerms((Plan *) lfirst(appendplans),
373 * Check access permissions for all relations listed in a range table.
376 ExecCheckRTPerms(List *rangeTable, CmdType operation)
380 foreach(lp, rangeTable)
382 RangeTblEntry *rte = lfirst(lp);
384 ExecCheckRTEPerms(rte, operation);
390 * Check access permissions for a single RTE.
393 ExecCheckRTEPerms(RangeTblEntry *rte, CmdType operation)
397 int32 aclcheck_result;
400 * If it's a subquery RTE, ignore it --- it will be checked when
401 * ExecCheckPlanPerms finds the SubqueryScan node for it.
406 relName = rte->relname;
409 * userid to check as: current user unless we have a setuid
412 * Note: GetUserId() is presently fast enough that there's no harm in
413 * calling it separately for each RTE. If that stops being true, we
414 * could call it once in ExecCheckQueryPerms and pass the userid down
415 * from there. But for now, no need for the extra clutter.
417 userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
419 #define CHECK(MODE) pg_aclcheck(relName, userid, MODE)
421 if (rte->checkForRead)
423 aclcheck_result = CHECK(ACL_SELECT);
424 if (aclcheck_result != ACLCHECK_OK)
425 elog(ERROR, "%s: %s",
426 relName, aclcheck_error_strings[aclcheck_result]);
429 if (rte->checkForWrite)
433 * Note: write access in a SELECT context means SELECT FOR UPDATE.
434 * Right now we don't distinguish that from true update as far as
435 * permissions checks are concerned.
440 aclcheck_result = CHECK(ACL_INSERT);
444 aclcheck_result = CHECK(ACL_UPDATE);
447 aclcheck_result = CHECK(ACL_DELETE);
450 elog(ERROR, "ExecCheckRTEPerms: bogus operation %d",
452 aclcheck_result = ACLCHECK_OK; /* keep compiler quiet */
455 if (aclcheck_result != ACLCHECK_OK)
456 elog(ERROR, "%s: %s",
457 relName, aclcheck_error_strings[aclcheck_result]);
462 /* ===============================================================
463 * ===============================================================
464 static routines follow
465 * ===============================================================
466 * ===============================================================
469 typedef struct execRowMark
476 typedef struct evalPlanQual
481 struct evalPlanQual *free;
484 /* ----------------------------------------------------------------
487 * Initializes the query plan: open files, allocate storage
488 * and start up the rule manager
489 * ----------------------------------------------------------------
492 InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
495 Relation intoRelationDesc;
499 * Do permissions checks.
501 ExecCheckQueryPerms(operation, parseTree, plan);
504 * get information from query descriptor
506 rangeTable = parseTree->rtable;
509 * initialize the node's execution state
511 estate->es_range_table = rangeTable;
514 * if there is a result relation, initialize result relation stuff
516 if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
518 List *resultRelations = parseTree->resultRelations;
519 int numResultRelations;
520 ResultRelInfo *resultRelInfos;
522 if (resultRelations != NIL)
526 * Multiple result relations (due to inheritance)
527 * parseTree->resultRelations identifies them all
529 ResultRelInfo *resultRelInfo;
531 numResultRelations = length(resultRelations);
532 resultRelInfos = (ResultRelInfo *)
533 palloc(numResultRelations * sizeof(ResultRelInfo));
534 resultRelInfo = resultRelInfos;
535 while (resultRelations != NIL)
537 initResultRelInfo(resultRelInfo,
538 lfirsti(resultRelations),
542 resultRelations = lnext(resultRelations);
549 * Single result relation identified by
550 * parseTree->resultRelation
552 numResultRelations = 1;
553 resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
554 initResultRelInfo(resultRelInfos,
555 parseTree->resultRelation,
560 estate->es_result_relations = resultRelInfos;
561 estate->es_num_result_relations = numResultRelations;
562 /* Initialize to first or only result rel */
563 estate->es_result_relation_info = resultRelInfos;
569 * if no result relation, then set state appropriately
571 estate->es_result_relations = NULL;
572 estate->es_num_result_relations = 0;
573 estate->es_result_relation_info = NULL;
577 * Have to lock relations selected for update
579 estate->es_rowMark = NIL;
580 if (parseTree->rowMarks != NIL)
584 foreach(l, parseTree->rowMarks)
586 Index rti = lfirsti(l);
587 Oid relid = getrelid(rti, rangeTable);
591 relation = heap_open(relid, RowShareLock);
592 erm = (execRowMark *) palloc(sizeof(execRowMark));
593 erm->relation = relation;
595 sprintf(erm->resname, "ctid%u", rti);
596 estate->es_rowMark = lappend(estate->es_rowMark, erm);
601 * initialize the executor "tuple" table. We need slots for all the
602 * plan nodes, plus possibly output slots for the junkfilter(s).
603 * At this point we aren't sure if we need junkfilters, so just add
604 * slots for them unconditionally.
607 int nSlots = ExecCountSlotsNode(plan);
609 if (parseTree->resultRelations != NIL)
610 nSlots += length(parseTree->resultRelations);
613 estate->es_tupleTable = ExecCreateTupleTable(nSlots);
616 /* mark EvalPlanQual not active */
617 estate->es_origPlan = plan;
618 estate->es_evalPlanQual = NULL;
619 estate->es_evTuple = NULL;
620 estate->es_evTupleNull = NULL;
621 estate->es_useEvalPlan = false;
624 * initialize the private state information for all the nodes in the
625 * query tree. This opens files, allocates storage and leaves us
626 * ready to start processing tuples.
628 ExecInitNode(plan, estate, NULL);
631 * Get the tuple descriptor describing the type of tuples to return.
632 * (this is especially important if we are creating a relation with
635 tupType = ExecGetTupType(plan); /* tuple descriptor */
638 * Initialize the junk filter if needed. SELECT and INSERT queries
639 * need a filter if there are any junk attrs in the tlist. UPDATE and
640 * DELETE always need one, since there's always a junk 'ctid'
641 * attribute present --- no need to look first.
644 bool junk_filter_needed = false;
651 foreach(tlist, plan->targetlist)
653 TargetEntry *tle = (TargetEntry *) lfirst(tlist);
655 if (tle->resdom->resjunk)
657 junk_filter_needed = true;
664 junk_filter_needed = true;
670 if (junk_filter_needed)
674 * If there are multiple result relations, each one needs its
675 * own junk filter. Note this is only possible for
676 * UPDATE/DELETE, so we can't be fooled by some needing a
677 * filter and some not.
679 if (parseTree->resultRelations != NIL)
682 ResultRelInfo *resultRelInfo;
684 /* Top plan had better be an Append here. */
685 Assert(IsA(plan, Append));
686 Assert(((Append *) plan)->isTarget);
687 subplans = ((Append *) plan)->appendplans;
688 Assert(length(subplans) == estate->es_num_result_relations);
689 resultRelInfo = estate->es_result_relations;
690 while (subplans != NIL)
692 Plan *subplan = (Plan *) lfirst(subplans);
695 j = ExecInitJunkFilter(subplan->targetlist,
696 ExecGetTupType(subplan),
697 ExecAllocTableSlot(estate->es_tupleTable));
698 resultRelInfo->ri_junkFilter = j;
700 subplans = lnext(subplans);
704 * Set active junkfilter too; at this point ExecInitAppend
705 * has already selected an active result relation...
707 estate->es_junkFilter =
708 estate->es_result_relation_info->ri_junkFilter;
712 /* Normal case with just one JunkFilter */
715 j = ExecInitJunkFilter(plan->targetlist,
717 ExecAllocTableSlot(estate->es_tupleTable));
718 estate->es_junkFilter = j;
719 if (estate->es_result_relation_info)
720 estate->es_result_relation_info->ri_junkFilter = j;
722 /* For SELECT, want to return the cleaned tuple type */
723 if (operation == CMD_SELECT)
724 tupType = j->jf_cleanTupType;
728 estate->es_junkFilter = NULL;
732 * initialize the "into" relation
734 intoRelationDesc = (Relation) NULL;
736 if (operation == CMD_SELECT)
742 if (!parseTree->isPortal)
746 * a select into table
748 if (parseTree->into != NULL)
752 * create the "into" relation
754 intoName = parseTree->into;
757 * have to copy tupType to get rid of constraints
759 tupdesc = CreateTupleDescCopy(tupType);
762 heap_create_with_catalog(intoName,
766 allowSystemTableMods);
768 FreeTupleDesc(tupdesc);
771 * Advance command counter so that the newly-created
772 * relation's catalog tuples will be visible to heap_open.
774 CommandCounterIncrement();
777 * If necessary, create a TOAST table for the into
778 * relation. Note that AlterTableCreateToastTable ends
779 * with CommandCounterIncrement(), so that the TOAST table
780 * will be visible for insertion.
782 AlterTableCreateToastTable(intoName, true);
784 intoRelationDesc = heap_open(intoRelationId,
785 AccessExclusiveLock);
790 estate->es_into_relation_descriptor = intoRelationDesc;
796 * Initialize ResultRelInfo data for one result relation
799 initResultRelInfo(ResultRelInfo *resultRelInfo,
800 Index resultRelationIndex,
804 Oid resultRelationOid;
805 Relation resultRelationDesc;
807 resultRelationOid = getrelid(resultRelationIndex, rangeTable);
808 resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);
810 switch (resultRelationDesc->rd_rel->relkind)
812 case RELKIND_SEQUENCE:
813 elog(ERROR, "You can't change sequence relation %s",
814 RelationGetRelationName(resultRelationDesc));
816 case RELKIND_TOASTVALUE:
817 elog(ERROR, "You can't change toast relation %s",
818 RelationGetRelationName(resultRelationDesc));
821 elog(ERROR, "You can't change view relation %s",
822 RelationGetRelationName(resultRelationDesc));
826 MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
827 resultRelInfo->type = T_ResultRelInfo;
828 resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
829 resultRelInfo->ri_RelationDesc = resultRelationDesc;
830 resultRelInfo->ri_NumIndices = 0;
831 resultRelInfo->ri_IndexRelationDescs = NULL;
832 resultRelInfo->ri_IndexRelationInfo = NULL;
833 resultRelInfo->ri_TrigDesc = resultRelationDesc->trigdesc;
834 resultRelInfo->ri_TrigFunctions = NULL;
835 resultRelInfo->ri_ConstraintExprs = NULL;
836 resultRelInfo->ri_junkFilter = NULL;
839 * If there are indices on the result relation, open them and save
840 * descriptors in the result relation info, so that we can add new
841 * index entries for the tuples we add/update. We need not do this
842 * for a DELETE, however, since deletion doesn't affect indexes.
844 if (resultRelationDesc->rd_rel->relhasindex &&
845 operation != CMD_DELETE)
846 ExecOpenIndices(resultRelInfo);
849 /* ----------------------------------------------------------------
852 * Cleans up the query plan -- closes files and free up storages
853 * ----------------------------------------------------------------
856 EndPlan(Plan *plan, EState *estate)
858 ResultRelInfo *resultRelInfo;
863 * shut down any PlanQual processing we were doing
865 if (estate->es_evalPlanQual != NULL)
866 EndEvalPlanQual(estate);
869 * shut down the node-type-specific query processing
871 ExecEndNode(plan, plan);
874 * destroy the executor "tuple" table.
876 ExecDropTupleTable(estate->es_tupleTable, true);
877 estate->es_tupleTable = NULL;
880 * close the result relation(s) if any, but hold locks until xact
881 * commit. Also clean up junkfilters if present.
883 resultRelInfo = estate->es_result_relations;
884 for (i = estate->es_num_result_relations; i > 0; i--)
886 /* Close indices and then the relation itself */
887 ExecCloseIndices(resultRelInfo);
888 heap_close(resultRelInfo->ri_RelationDesc, NoLock);
889 /* Delete the junkfilter if any */
890 if (resultRelInfo->ri_junkFilter != NULL)
891 ExecFreeJunkFilter(resultRelInfo->ri_junkFilter);
896 * close the "into" relation if necessary, again keeping lock
898 if (estate->es_into_relation_descriptor != NULL)
899 heap_close(estate->es_into_relation_descriptor, NoLock);
902 * There might be a junkfilter without a result relation.
904 if (estate->es_num_result_relations == 0 &&
905 estate->es_junkFilter != NULL)
907 ExecFreeJunkFilter(estate->es_junkFilter);
908 estate->es_junkFilter = NULL;
912 * close any relations selected FOR UPDATE, again keeping locks
914 foreach(l, estate->es_rowMark)
916 execRowMark *erm = lfirst(l);
918 heap_close(erm->relation, NoLock);
922 /* ----------------------------------------------------------------
925 * processes the query plan to retrieve 'numberTuples' tuples in the
926 * direction specified.
927 * Retrieves all tuples if tupleCount is 0
929 * result is either a slot containing the last tuple in the case
930 * of a RETRIEVE or NULL otherwise.
932 * Note: the ctid attribute is a 'junk' attribute that is removed before the
934 * ----------------------------------------------------------------
936 static TupleTableSlot *
937 ExecutePlan(EState *estate,
941 ScanDirection direction,
942 DestReceiver *destfunc)
944 JunkFilter *junkfilter;
945 TupleTableSlot *slot;
946 ItemPointer tupleid = NULL;
947 ItemPointerData tuple_ctid;
948 long current_tuple_count;
949 TupleTableSlot *result;
952 * initialize local variables
955 current_tuple_count = 0;
961 estate->es_direction = direction;
964 * Loop until we've processed the proper number of tuples from the
970 /* Reset the per-output-tuple exprcontext */
971 ResetPerTupleExprContext(estate);
974 * Execute the plan and obtain a tuple
976 /* at the top level, the parent of a plan (2nd arg) is itself */
978 if (estate->es_useEvalPlan)
980 slot = EvalPlanQualNext(estate);
982 slot = ExecProcNode(plan, plan);
985 slot = ExecProcNode(plan, plan);
988 * if the tuple is null, then we assume there is nothing more to
989 * process so we just return null...
998 * if we have a junk filter, then project a new tuple with the
1001 * Store this new "clean" tuple in the junkfilter's resultSlot.
1002 * (Formerly, we stored it back over the "dirty" tuple, which is
1003 * WRONG because that tuple slot has the wrong descriptor.)
1005 * Also, extract all the junk information we need.
1007 if ((junkfilter = estate->es_junkFilter) != (JunkFilter *) NULL)
1014 * extract the 'ctid' junk attribute.
1016 if (operation == CMD_UPDATE || operation == CMD_DELETE)
1018 if (!ExecGetJunkAttribute(junkfilter,
1023 elog(ERROR, "ExecutePlan: NO (junk) `ctid' was found!");
1025 /* shouldn't ever get a null result... */
1027 elog(ERROR, "ExecutePlan: (junk) `ctid' is NULL!");
1029 tupleid = (ItemPointer) DatumGetPointer(datum);
1030 tuple_ctid = *tupleid; /* make sure we don't free the
1032 tupleid = &tuple_ctid;
1034 else if (estate->es_rowMark != NIL)
1039 foreach(l, estate->es_rowMark)
1041 execRowMark *erm = lfirst(l);
1043 HeapTupleData tuple;
1044 TupleTableSlot *newSlot;
1047 if (!ExecGetJunkAttribute(junkfilter,
1052 elog(ERROR, "ExecutePlan: NO (junk) `%s' was found!",
1055 /* shouldn't ever get a null result... */
1057 elog(ERROR, "ExecutePlan: (junk) `%s' is NULL!",
1060 tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
1061 test = heap_mark4update(erm->relation, &tuple, &buffer);
1062 ReleaseBuffer(buffer);
1065 case HeapTupleSelfUpdated:
1066 case HeapTupleMayBeUpdated:
1069 case HeapTupleUpdated:
1070 if (XactIsoLevel == XACT_SERIALIZABLE)
1071 elog(ERROR, "Can't serialize access due to concurrent update");
1072 if (!(ItemPointerEquals(&(tuple.t_self),
1073 (ItemPointer) DatumGetPointer(datum))))
1075 newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
1076 if (!(TupIsNull(newSlot)))
1079 estate->es_useEvalPlan = true;
1085 * if tuple was deleted or PlanQual failed for
1086 * updated tuple - we must not return this
1092 elog(ERROR, "Unknown status %u from heap_mark4update", test);
1099 * Finally create a new "clean" tuple with all junk attributes
1102 newTuple = ExecRemoveJunk(junkfilter, slot);
1104 slot = ExecStoreTuple(newTuple, /* tuple to store */
1105 junkfilter->jf_resultSlot, /* dest slot */
1106 InvalidBuffer, /* this tuple has no
1108 true); /* tuple should be pfreed */
1109 } /* if (junkfilter... */
1112 * now that we have a tuple, do the appropriate thing with it..
1113 * either return it to the user, add it to a relation someplace,
1114 * delete it from a relation, or modify some of its attributes.
1120 ExecRetrieve(slot, /* slot containing tuple */
1121 destfunc, /* destination's tuple-receiver
1128 ExecAppend(slot, tupleid, estate);
1133 ExecDelete(slot, tupleid, estate);
1138 ExecReplace(slot, tupleid, estate);
1143 elog(DEBUG, "ExecutePlan: unknown operation in queryDesc");
1149 * check our tuple count.. if we've processed the proper number
1150 * then quit, else loop again and process more tuples..
1152 current_tuple_count++;
1153 if (numberTuples == current_tuple_count)
1158 * here, result is either a slot containing a tuple in the case of a
1159 * RETRIEVE or NULL otherwise.
1164 /* ----------------------------------------------------------------
1167 * RETRIEVEs are easy.. we just pass the tuple to the appropriate
1168 * print function. The only complexity is when we do a
1169 * "retrieve into", in which case we insert the tuple into
1170 * the appropriate relation (note: this is a newly created relation
1171 * so we don't need to worry about indices or locks.)
1172 * ----------------------------------------------------------------
1175 ExecRetrieve(TupleTableSlot *slot,
1176 DestReceiver *destfunc,
1183 * get the heap tuple out of the tuple table slot
1186 attrtype = slot->ttc_tupleDescriptor;
1189 * insert the tuple into the "into relation"
1191 if (estate->es_into_relation_descriptor != NULL)
1193 heap_insert(estate->es_into_relation_descriptor, tuple);
1198 * send the tuple to the front end (or the screen)
1200 (*destfunc->receiveTuple) (tuple, attrtype, destfunc);
1202 (estate->es_processed)++;
1205 /* ----------------------------------------------------------------
1208 * APPENDs are trickier.. we have to insert the tuple into
1209 * the base relation and insert appropriate tuples into the
1211 * ----------------------------------------------------------------
1215 ExecAppend(TupleTableSlot *slot,
1216 ItemPointer tupleid,
1220 ResultRelInfo *resultRelInfo;
1221 Relation resultRelationDesc;
1226 * get the heap tuple out of the tuple table slot
1231 * get information on the (current) result relation
1233 resultRelInfo = estate->es_result_relation_info;
1234 resultRelationDesc = resultRelInfo->ri_RelationDesc;
1236 /* BEFORE ROW INSERT Triggers */
1237 if (resultRelInfo->ri_TrigDesc &&
1238 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_INSERT] > 0)
1242 newtuple = ExecBRInsertTriggers(estate, resultRelInfo, tuple);
1244 if (newtuple == NULL) /* "do nothing" */
1247 if (newtuple != tuple) /* modified by Trigger(s) */
1251 * Insert modified tuple into tuple table slot, replacing the
1252 * original. We assume that it was allocated in per-tuple
1253 * memory context, and therefore will go away by itself. The
1254 * tuple table slot should not try to clear it.
1256 ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1262 * Check the constraints of the tuple
1264 if (resultRelationDesc->rd_att->constr)
1265 ExecConstraints("ExecAppend", resultRelInfo, slot, estate);
1270 newId = heap_insert(resultRelationDesc, tuple);
1273 (estate->es_processed)++;
1274 estate->es_lastoid = newId;
1279 * Note: heap_insert adds a new tuple to a relation. As a side effect,
1280 * the tupleid of the new tuple is placed in the new tuple's t_ctid
1283 numIndices = resultRelInfo->ri_NumIndices;
1285 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, false);
1287 /* AFTER ROW INSERT Triggers */
1288 if (resultRelInfo->ri_TrigDesc)
1289 ExecARInsertTriggers(estate, resultRelInfo, tuple);
1292 /* ----------------------------------------------------------------
1295 * DELETE is like append, we delete the tuple and its
1297 * ----------------------------------------------------------------
1300 ExecDelete(TupleTableSlot *slot,
1301 ItemPointer tupleid,
1304 ResultRelInfo *resultRelInfo;
1305 Relation resultRelationDesc;
1306 ItemPointerData ctid;
1310 * get information on the (current) result relation
1312 resultRelInfo = estate->es_result_relation_info;
1313 resultRelationDesc = resultRelInfo->ri_RelationDesc;
1315 /* BEFORE ROW DELETE Triggers */
1316 if (resultRelInfo->ri_TrigDesc &&
1317 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_DELETE] > 0)
1321 dodelete = ExecBRDeleteTriggers(estate, resultRelInfo, tupleid);
1323 if (!dodelete) /* "do nothing" */
1331 result = heap_delete(resultRelationDesc, tupleid, &ctid);
1334 case HeapTupleSelfUpdated:
1337 case HeapTupleMayBeUpdated:
1340 case HeapTupleUpdated:
1341 if (XactIsoLevel == XACT_SERIALIZABLE)
1342 elog(ERROR, "Can't serialize access due to concurrent update");
1343 else if (!(ItemPointerEquals(tupleid, &ctid)))
1345 TupleTableSlot *epqslot = EvalPlanQual(estate,
1346 resultRelInfo->ri_RangeTableIndex, &ctid);
1348 if (!TupIsNull(epqslot))
1354 /* tuple already deleted; nothing to do */
1358 elog(ERROR, "Unknown status %u from heap_delete", result);
1363 (estate->es_processed)++;
1366 * Note: Normally one would think that we have to delete index tuples
1367 * associated with the heap tuple now..
1369 * ... but in POSTGRES, we have no need to do this because the vacuum
1370 * daemon automatically opens an index scan and deletes index tuples
1371 * when it finds deleted heap tuples. -cim 9/27/89
1374 /* AFTER ROW DELETE Triggers */
1375 if (resultRelInfo->ri_TrigDesc)
1376 ExecARDeleteTriggers(estate, resultRelInfo, tupleid);
1379 /* ----------------------------------------------------------------
1382 * note: we can't run replace queries with transactions
1383 * off because replaces are actually appends and our
1384 * scan will mistakenly loop forever, replacing the tuple
1385 * it just appended.. This should be fixed but until it
1386 * is, we don't want to get stuck in an infinite loop
1387 * which corrupts your database..
1388 * ----------------------------------------------------------------
1391 ExecReplace(TupleTableSlot *slot,
1392 ItemPointer tupleid,
1396 ResultRelInfo *resultRelInfo;
1397 Relation resultRelationDesc;
1398 ItemPointerData ctid;
1403 * abort the operation if not running transactions
1405 if (IsBootstrapProcessingMode())
1407 elog(NOTICE, "ExecReplace: replace can't run without transactions");
1412 * get the heap tuple out of the tuple table slot
1417 * get information on the (current) result relation
1419 resultRelInfo = estate->es_result_relation_info;
1420 resultRelationDesc = resultRelInfo->ri_RelationDesc;
1422 /* BEFORE ROW UPDATE Triggers */
1423 if (resultRelInfo->ri_TrigDesc &&
1424 resultRelInfo->ri_TrigDesc->n_before_row[TRIGGER_EVENT_UPDATE] > 0)
1428 newtuple = ExecBRUpdateTriggers(estate, resultRelInfo,
1431 if (newtuple == NULL) /* "do nothing" */
1434 if (newtuple != tuple) /* modified by Trigger(s) */
1438 * Insert modified tuple into tuple table slot, replacing the
1439 * original. We assume that it was allocated in per-tuple
1440 * memory context, and therefore will go away by itself. The
1441 * tuple table slot should not try to clear it.
1443 ExecStoreTuple(newtuple, slot, InvalidBuffer, false);
1449 * Check the constraints of the tuple
1451 * If we generate a new candidate tuple after EvalPlanQual testing,
1452 * we must loop back here and recheck constraints. (We don't need to
1453 * redo triggers, however. If there are any BEFORE triggers then
1454 * trigger.c will have done mark4update to lock the correct tuple,
1455 * so there's no need to do them again.)
1458 if (resultRelationDesc->rd_att->constr)
1459 ExecConstraints("ExecReplace", resultRelInfo, slot, estate);
1462 * replace the heap tuple
1464 result = heap_update(resultRelationDesc, tupleid, tuple, &ctid);
1467 case HeapTupleSelfUpdated:
1470 case HeapTupleMayBeUpdated:
1473 case HeapTupleUpdated:
1474 if (XactIsoLevel == XACT_SERIALIZABLE)
1475 elog(ERROR, "Can't serialize access due to concurrent update");
1476 else if (!(ItemPointerEquals(tupleid, &ctid)))
1478 TupleTableSlot *epqslot = EvalPlanQual(estate,
1479 resultRelInfo->ri_RangeTableIndex, &ctid);
1481 if (!TupIsNull(epqslot))
1484 tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
1485 slot = ExecStoreTuple(tuple,
1486 estate->es_junkFilter->jf_resultSlot,
1487 InvalidBuffer, true);
1491 /* tuple already deleted; nothing to do */
1495 elog(ERROR, "Unknown status %u from heap_update", result);
1500 (estate->es_processed)++;
1503 * Note: instead of having to update the old index tuples associated
1504 * with the heap tuple, all we do is form and insert new index tuples.
1505 * This is because replaces are actually deletes and inserts and index
1506 * tuple deletion is done automagically by the vacuum daemon. All we
1507 * do is insert new index tuples. -cim 9/27/89
1513 * heap_update updates a tuple in the base relation by invalidating it
1514 * and then appending a new tuple to the relation. As a side effect,
1515 * the tupleid of the new tuple is placed in the new tuple's t_ctid
1516 * field. So we now insert index tuples using the new tupleid stored
1520 numIndices = resultRelInfo->ri_NumIndices;
1522 ExecInsertIndexTuples(slot, &(tuple->t_self), estate, true);
1524 /* AFTER ROW UPDATE Triggers */
1525 if (resultRelInfo->ri_TrigDesc)
1526 ExecARUpdateTriggers(estate, resultRelInfo, tupleid, tuple);
1530 ExecRelCheck(ResultRelInfo *resultRelInfo,
1531 TupleTableSlot *slot, EState *estate)
1533 Relation rel = resultRelInfo->ri_RelationDesc;
1534 int ncheck = rel->rd_att->constr->num_check;
1535 ConstrCheck *check = rel->rd_att->constr->check;
1536 ExprContext *econtext;
1537 MemoryContext oldContext;
1542 * If first time through for this result relation, build expression
1543 * nodetrees for rel's constraint expressions. Keep them in the
1544 * per-query memory context so they'll survive throughout the query.
1546 if (resultRelInfo->ri_ConstraintExprs == NULL)
1548 oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
1549 resultRelInfo->ri_ConstraintExprs =
1550 (List **) palloc(ncheck * sizeof(List *));
1551 for (i = 0; i < ncheck; i++)
1553 qual = (List *) stringToNode(check[i].ccbin);
1554 resultRelInfo->ri_ConstraintExprs[i] = qual;
1556 MemoryContextSwitchTo(oldContext);
1560 * We will use the EState's per-tuple context for evaluating
1561 * constraint expressions (creating it if it's not already there).
1563 econtext = GetPerTupleExprContext(estate);
1565 /* Arrange for econtext's scan tuple to be the tuple under test */
1566 econtext->ecxt_scantuple = slot;
1568 /* And evaluate the constraints */
1569 for (i = 0; i < ncheck; i++)
1571 qual = resultRelInfo->ri_ConstraintExprs[i];
1574 * NOTE: SQL92 specifies that a NULL result from a constraint
1575 * expression is not to be treated as a failure. Therefore, tell
1576 * ExecQual to return TRUE for NULL.
1578 if (!ExecQual(qual, econtext, true))
1579 return check[i].ccname;
1582 /* NULL result means no error */
1583 return (char *) NULL;
1587 ExecConstraints(char *caller, ResultRelInfo *resultRelInfo,
1588 TupleTableSlot *slot, EState *estate)
1590 Relation rel = resultRelInfo->ri_RelationDesc;
1591 HeapTuple tuple = slot->val;
1592 TupleConstr *constr = rel->rd_att->constr;
1596 if (constr->has_not_null)
1598 int natts = rel->rd_att->natts;
1601 for (attrChk = 1; attrChk <= natts; attrChk++)
1603 if (rel->rd_att->attrs[attrChk - 1]->attnotnull &&
1604 heap_attisnull(tuple, attrChk))
1605 elog(ERROR, "%s: Fail to add null value in not null attribute %s",
1606 caller, NameStr(rel->rd_att->attrs[attrChk - 1]->attname));
1610 if (constr->num_check > 0)
1614 if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
1615 elog(ERROR, "%s: rejected due to CHECK constraint %s",
1621 * Check a modified tuple to see if we want to process its updated version
1622 * under READ COMMITTED rules.
1624 * See backend/executor/README for some info about how this works.
1627 EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
1632 HeapTupleData tuple;
1633 HeapTuple copyTuple = NULL;
1640 * find relation containing target tuple
1642 if (estate->es_result_relation_info != NULL &&
1643 estate->es_result_relation_info->ri_RangeTableIndex == rti)
1645 relation = estate->es_result_relation_info->ri_RelationDesc;
1652 foreach(l, estate->es_rowMark)
1654 if (((execRowMark *) lfirst(l))->rti == rti)
1656 relation = ((execRowMark *) lfirst(l))->relation;
1660 if (relation == NULL)
1661 elog(ERROR, "EvalPlanQual: can't find RTE %d", (int) rti);
1667 * Loop here to deal with updated or busy tuples
1669 tuple.t_self = *tid;
1674 heap_fetch(relation, SnapshotDirty, &tuple, &buffer, NULL);
1675 if (tuple.t_data != NULL)
1677 TransactionId xwait = SnapshotDirty->xmax;
1679 if (TransactionIdIsValid(SnapshotDirty->xmin))
1680 elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
1683 * If tuple is being updated by other transaction then we have
1684 * to wait for its commit/abort.
1686 if (TransactionIdIsValid(xwait))
1688 ReleaseBuffer(buffer);
1689 XactLockTableWait(xwait);
1694 * We got tuple - now copy it for use by recheck query.
1696 copyTuple = heap_copytuple(&tuple);
1697 ReleaseBuffer(buffer);
1702 * Oops! Invalid tuple. Have to check is it updated or deleted.
1703 * Note that it's possible to get invalid SnapshotDirty->tid if
1704 * tuple updated by this transaction. Have we to check this ?
1706 if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
1707 !(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
1709 /* updated, so look at the updated copy */
1710 tuple.t_self = SnapshotDirty->tid;
1715 * Deleted or updated by this transaction; forget it.
1721 * For UPDATE/DELETE we have to return tid of actual row we're
1724 *tid = tuple.t_self;
1727 * Need to run a recheck subquery. Find or create a PQ stack entry.
1729 epq = (evalPlanQual *) estate->es_evalPlanQual;
1730 rtsize = length(estate->es_range_table);
1733 if (epq != NULL && epq->rti == 0)
1735 /* Top PQ stack entry is idle, so re-use it */
1736 Assert(!(estate->es_useEvalPlan) &&
1737 epq->estate.es_evalPlanQual == NULL);
1743 * If this is request for another RTE - Ra, - then we have to check
1744 * wasn't PlanQual requested for Ra already and if so then Ra' row was
1745 * updated again and we have to re-start old execution for Ra and
1746 * forget all what we done after Ra was suspended. Cool? -:))
1748 if (epq != NULL && epq->rti != rti &&
1749 epq->estate.es_evTuple[rti - 1] != NULL)
1753 evalPlanQual *oldepq;
1755 /* pop previous PlanQual from the stack */
1756 epqstate = &(epq->estate);
1757 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1758 Assert(oldepq->rti != 0);
1759 /* stop execution */
1760 ExecEndNode(epq->plan, epq->plan);
1761 ExecDropTupleTable(epqstate->es_tupleTable, true);
1762 epqstate->es_tupleTable = NULL;
1763 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1764 epqstate->es_evTuple[epq->rti - 1] = NULL;
1765 /* push current PQ to freePQ stack */
1768 estate->es_evalPlanQual = (Pointer) epq;
1769 } while (epq->rti != rti);
1773 * If we are requested for another RTE then we have to suspend
1774 * execution of current PlanQual and start execution for new one.
1776 if (epq == NULL || epq->rti != rti)
1778 /* try to reuse plan used previously */
1779 evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;
1781 if (newepq == NULL) /* first call or freePQ stack is empty */
1783 newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
1784 newepq->free = NULL;
1786 * Each stack level has its own copy of the plan tree. This
1787 * is wasteful, but necessary as long as plan nodes point to
1788 * exec state nodes rather than vice versa. Note that copyfuncs.c
1789 * doesn't attempt to copy the exec state nodes, which is a good
1790 * thing in this situation.
1792 newepq->plan = copyObject(estate->es_origPlan);
1794 * Init stack level's EState. We share top level's copy of
1795 * es_result_relations array and other non-changing status.
1796 * We need our own tupletable, es_param_exec_vals, and other
1799 epqstate = &(newepq->estate);
1800 memcpy(epqstate, estate, sizeof(EState));
1801 epqstate->es_direction = ForwardScanDirection;
1802 if (estate->es_origPlan->nParamExec > 0)
1803 epqstate->es_param_exec_vals = (ParamExecData *)
1804 palloc(estate->es_origPlan->nParamExec *
1805 sizeof(ParamExecData));
1806 epqstate->es_tupleTable = NULL;
1807 epqstate->es_per_tuple_exprcontext = NULL;
1809 * Each epqstate must have its own es_evTupleNull state,
1810 * but all the stack entries share es_evTuple state. This
1811 * allows sub-rechecks to inherit the value being examined by
1814 epqstate->es_evTupleNull = (bool *) palloc(rtsize * sizeof(bool));
1817 /* first PQ stack entry */
1818 epqstate->es_evTuple = (HeapTuple *)
1819 palloc(rtsize * sizeof(HeapTuple));
1820 memset(epqstate->es_evTuple, 0, rtsize * sizeof(HeapTuple));
1824 /* later stack entries share the same storage */
1825 epqstate->es_evTuple = epq->estate.es_evTuple;
1830 /* recycle previously used EState */
1831 epqstate = &(newepq->estate);
1833 /* push current PQ to the stack */
1834 epqstate->es_evalPlanQual = (Pointer) epq;
1836 estate->es_evalPlanQual = (Pointer) epq;
1841 Assert(epq->rti == rti);
1842 epqstate = &(epq->estate);
1845 * Ok - we're requested for the same RTE. Unfortunately we still
1846 * have to end and restart execution of the plan, because ExecReScan
1847 * wouldn't ensure that upper plan nodes would reset themselves. We
1848 * could make that work if insertion of the target tuple were integrated
1849 * with the Param mechanism somehow, so that the upper plan nodes know
1850 * that their children's outputs have changed.
1854 /* stop execution */
1855 ExecEndNode(epq->plan, epq->plan);
1856 ExecDropTupleTable(epqstate->es_tupleTable, true);
1857 epqstate->es_tupleTable = NULL;
1861 * free old RTE' tuple, if any, and store target tuple where relation's
1862 * scan node will see it
1864 if (epqstate->es_evTuple[rti - 1] != NULL)
1865 heap_freetuple(epqstate->es_evTuple[rti - 1]);
1866 epqstate->es_evTuple[rti - 1] = copyTuple;
1869 * Initialize for new recheck query; be careful to copy down state
1870 * that might have changed in top EState.
1872 epqstate->es_result_relation_info = estate->es_result_relation_info;
1873 epqstate->es_junkFilter = estate->es_junkFilter;
1874 if (estate->es_origPlan->nParamExec > 0)
1875 memset(epqstate->es_param_exec_vals, 0,
1876 estate->es_origPlan->nParamExec * sizeof(ParamExecData));
1877 memset(epqstate->es_evTupleNull, false, rtsize * sizeof(bool));
1878 epqstate->es_useEvalPlan = false;
1879 Assert(epqstate->es_tupleTable == NULL);
1880 epqstate->es_tupleTable =
1881 ExecCreateTupleTable(estate->es_tupleTable->size);
1883 ExecInitNode(epq->plan, epqstate, NULL);
1885 return EvalPlanQualNext(estate);
1888 static TupleTableSlot *
1889 EvalPlanQualNext(EState *estate)
1891 evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1892 EState *epqstate = &(epq->estate);
1893 evalPlanQual *oldepq;
1894 TupleTableSlot *slot;
1896 Assert(epq->rti != 0);
1899 slot = ExecProcNode(epq->plan, epq->plan);
1902 * No more tuples for this PQ. Continue previous one.
1904 if (TupIsNull(slot))
1906 /* stop execution */
1907 ExecEndNode(epq->plan, epq->plan);
1908 ExecDropTupleTable(epqstate->es_tupleTable, true);
1909 epqstate->es_tupleTable = NULL;
1910 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1911 epqstate->es_evTuple[epq->rti - 1] = NULL;
1912 /* pop old PQ from the stack */
1913 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1914 if (oldepq == (evalPlanQual *) NULL)
1916 epq->rti = 0; /* this is the first (oldest) */
1917 estate->es_useEvalPlan = false; /* PQ - mark as free and */
1918 return (NULL); /* continue Query execution */
1920 Assert(oldepq->rti != 0);
1921 /* push current PQ to freePQ stack */
1924 epqstate = &(epq->estate);
1925 estate->es_evalPlanQual = (Pointer) epq;
1933 EndEvalPlanQual(EState *estate)
1935 evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
1936 EState *epqstate = &(epq->estate);
1937 evalPlanQual *oldepq;
1939 if (epq->rti == 0) /* plans already shutdowned */
1941 Assert(epq->estate.es_evalPlanQual == NULL);
1947 /* stop execution */
1948 ExecEndNode(epq->plan, epq->plan);
1949 ExecDropTupleTable(epqstate->es_tupleTable, true);
1950 epqstate->es_tupleTable = NULL;
1951 if (epqstate->es_evTuple[epq->rti - 1] != NULL)
1953 heap_freetuple(epqstate->es_evTuple[epq->rti - 1]);
1954 epqstate->es_evTuple[epq->rti - 1] = NULL;
1956 /* pop old PQ from the stack */
1957 oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
1958 if (oldepq == (evalPlanQual *) NULL)
1960 epq->rti = 0; /* this is the first (oldest) */
1961 estate->es_useEvalPlan = false; /* PQ - mark as free */
1964 Assert(oldepq->rti != 0);
1965 /* push current PQ to freePQ stack */
1968 epqstate = &(epq->estate);
1969 estate->es_evalPlanQual = (Pointer) epq;