/*------------------------------------------------------------------------- * * execUtils.c * miscellaneous executor utility routines * * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * src/backend/executor/execUtils.c * *------------------------------------------------------------------------- */ /* * INTERFACE ROUTINES * CreateExecutorState Create/delete executor working state * FreeExecutorState * CreateExprContext * CreateStandaloneExprContext * FreeExprContext * ReScanExprContext * * ExecAssignExprContext Common code for plan node init routines. * ExecAssignResultType * etc * * ExecOpenScanRelation Common code for scan node init routines. * ExecCloseScanRelation * * ExecOpenIndices \ * ExecCloseIndices | referenced by InitPlan, EndPlan, * ExecInsertIndexTuples / ExecInsert, ExecUpdate * * RegisterExprContextCallback Register function shutdown callback * UnregisterExprContextCallback Deregister function shutdown callback * * NOTES * This file has traditionally been the place to stick misc. * executor support stuff that doesn't really go anyplace else. */ #include "postgres.h" #include "access/genam.h" #include "access/heapam.h" #include "access/relscan.h" #include "access/transam.h" #include "catalog/index.h" #include "executor/execdebug.h" #include "nodes/nodeFuncs.h" #include "parser/parsetree.h" #include "storage/lmgr.h" #include "utils/memutils.h" #include "utils/relcache.h" #include "utils/tqual.h" static bool get_last_attnums(Node *node, ProjectionInfo *projInfo); static bool index_recheck_constraint(Relation index, Oid *constr_procs, Datum *existing_values, bool *existing_isnull, Datum *new_values); static void ShutdownExprContext(ExprContext *econtext, bool isCommit); /* ---------------------------------------------------------------- * Executor state and memory management functions * ---------------------------------------------------------------- */ /* ---------------- * CreateExecutorState * * Create and initialize an EState node, which is the root of * working storage for an entire Executor invocation. * * Principally, this creates the per-query memory context that will be * used to hold all working data that lives till the end of the query. * Note that the per-query context will become a child of the caller's * CurrentMemoryContext. * ---------------- */ EState * CreateExecutorState(void) { EState *estate; MemoryContext qcontext; MemoryContext oldcontext; /* * Create the per-query context for this Executor run. */ qcontext = AllocSetContextCreate(CurrentMemoryContext, "ExecutorState", ALLOCSET_DEFAULT_MINSIZE, ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE); /* * Make the EState node within the per-query context. This way, we don't * need a separate pfree() operation for it at shutdown. */ oldcontext = MemoryContextSwitchTo(qcontext); estate = makeNode(EState); /* * Initialize all fields of the Executor State structure */ estate->es_direction = ForwardScanDirection; estate->es_snapshot = SnapshotNow; estate->es_crosscheck_snapshot = InvalidSnapshot; /* no crosscheck */ estate->es_range_table = NIL; estate->es_plannedstmt = NULL; estate->es_junkFilter = NULL; estate->es_output_cid = (CommandId) 0; estate->es_result_relations = NULL; estate->es_num_result_relations = 0; estate->es_result_relation_info = NULL; estate->es_trig_target_relations = NIL; estate->es_trig_tuple_slot = NULL; estate->es_trig_oldtup_slot = NULL; estate->es_param_list_info = NULL; estate->es_param_exec_vals = NULL; estate->es_query_cxt = qcontext; estate->es_tupleTable = NIL; estate->es_rowMarks = NIL; estate->es_processed = 0; estate->es_lastoid = InvalidOid; estate->es_instrument = false; estate->es_select_into = false; estate->es_into_oids = false; estate->es_exprcontexts = NIL; estate->es_subplanstates = NIL; estate->es_per_tuple_exprcontext = NULL; estate->es_epqTuple = NULL; estate->es_epqTupleSet = NULL; estate->es_epqScanDone = NULL; /* * Return the executor state structure */ MemoryContextSwitchTo(oldcontext); return estate; } /* ---------------- * FreeExecutorState * * Release an EState along with all remaining working storage. * * Note: this is not responsible for releasing non-memory resources, * such as open relations or buffer pins. But it will shut down any * still-active ExprContexts within the EState. That is sufficient * cleanup for situations where the EState has only been used for expression * evaluation, and not to run a complete Plan. * * This can be called in any memory context ... so long as it's not one * of the ones to be freed. * ---------------- */ void FreeExecutorState(EState *estate) { /* * Shut down and free any remaining ExprContexts. We do this explicitly * to ensure that any remaining shutdown callbacks get called (since they * might need to release resources that aren't simply memory within the * per-query memory context). */ while (estate->es_exprcontexts) { /* * XXX: seems there ought to be a faster way to implement this than * repeated list_delete(), no? */ FreeExprContext((ExprContext *) linitial(estate->es_exprcontexts), true); /* FreeExprContext removed the list link for us */ } /* * Free the per-query memory context, thereby releasing all working * memory, including the EState node itself. */ MemoryContextDelete(estate->es_query_cxt); } /* ---------------- * CreateExprContext * * Create a context for expression evaluation within an EState. * * An executor run may require multiple ExprContexts (we usually make one * for each Plan node, and a separate one for per-output-tuple processing * such as constraint checking). Each ExprContext has its own "per-tuple" * memory context. * * Note we make no assumption about the caller's memory context. * ---------------- */ ExprContext * CreateExprContext(EState *estate) { ExprContext *econtext; MemoryContext oldcontext; /* Create the ExprContext node within the per-query memory context */ oldcontext = MemoryContextSwitchTo(estate->es_query_cxt); econtext = makeNode(ExprContext); /* Initialize fields of ExprContext */ econtext->ecxt_scantuple = NULL; econtext->ecxt_innertuple = NULL; econtext->ecxt_outertuple = NULL; econtext->ecxt_per_query_memory = estate->es_query_cxt; /* * Create working memory for expression evaluation in this context. */ econtext->ecxt_per_tuple_memory = AllocSetContextCreate(estate->es_query_cxt, "ExprContext", ALLOCSET_DEFAULT_MINSIZE, ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE); econtext->ecxt_param_exec_vals = estate->es_param_exec_vals; econtext->ecxt_param_list_info = estate->es_param_list_info; econtext->ecxt_aggvalues = NULL; econtext->ecxt_aggnulls = NULL; econtext->caseValue_datum = (Datum) 0; econtext->caseValue_isNull = true; econtext->domainValue_datum = (Datum) 0; econtext->domainValue_isNull = true; econtext->ecxt_estate = estate; econtext->ecxt_callbacks = NULL; /* * Link the ExprContext into the EState to ensure it is shut down when the * EState is freed. Because we use lcons(), shutdowns will occur in * reverse order of creation, which may not be essential but can't hurt. */ estate->es_exprcontexts = lcons(econtext, estate->es_exprcontexts); MemoryContextSwitchTo(oldcontext); return econtext; } /* ---------------- * CreateStandaloneExprContext * * Create a context for standalone expression evaluation. * * An ExprContext made this way can be used for evaluation of expressions * that contain no Params, subplans, or Var references (it might work to * put tuple references into the scantuple field, but it seems unwise). * * The ExprContext struct is allocated in the caller's current memory * context, which also becomes its "per query" context. * * It is caller's responsibility to free the ExprContext when done, * or at least ensure that any shutdown callbacks have been called * (ReScanExprContext() is suitable). Otherwise, non-memory resources * might be leaked. * ---------------- */ ExprContext * CreateStandaloneExprContext(void) { ExprContext *econtext; /* Create the ExprContext node within the caller's memory context */ econtext = makeNode(ExprContext); /* Initialize fields of ExprContext */ econtext->ecxt_scantuple = NULL; econtext->ecxt_innertuple = NULL; econtext->ecxt_outertuple = NULL; econtext->ecxt_per_query_memory = CurrentMemoryContext; /* * Create working memory for expression evaluation in this context. */ econtext->ecxt_per_tuple_memory = AllocSetContextCreate(CurrentMemoryContext, "ExprContext", ALLOCSET_DEFAULT_MINSIZE, ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE); econtext->ecxt_param_exec_vals = NULL; econtext->ecxt_param_list_info = NULL; econtext->ecxt_aggvalues = NULL; econtext->ecxt_aggnulls = NULL; econtext->caseValue_datum = (Datum) 0; econtext->caseValue_isNull = true; econtext->domainValue_datum = (Datum) 0; econtext->domainValue_isNull = true; econtext->ecxt_estate = NULL; econtext->ecxt_callbacks = NULL; return econtext; } /* ---------------- * FreeExprContext * * Free an expression context, including calling any remaining * shutdown callbacks. * * Since we free the temporary context used for expression evaluation, * any previously computed pass-by-reference expression result will go away! * * If isCommit is false, we are being called in error cleanup, and should * not call callbacks but only release memory. (It might be better to call * the callbacks and pass the isCommit flag to them, but that would require * more invasive code changes than currently seems justified.) * * Note we make no assumption about the caller's memory context. * ---------------- */ void FreeExprContext(ExprContext *econtext, bool isCommit) { EState *estate; /* Call any registered callbacks */ ShutdownExprContext(econtext, isCommit); /* And clean up the memory used */ MemoryContextDelete(econtext->ecxt_per_tuple_memory); /* Unlink self from owning EState, if any */ estate = econtext->ecxt_estate; if (estate) estate->es_exprcontexts = list_delete_ptr(estate->es_exprcontexts, econtext); /* And delete the ExprContext node */ pfree(econtext); } /* * ReScanExprContext * * Reset an expression context in preparation for a rescan of its * plan node. This requires calling any registered shutdown callbacks, * since any partially complete set-returning-functions must be canceled. * * Note we make no assumption about the caller's memory context. */ void ReScanExprContext(ExprContext *econtext) { /* Call any registered callbacks */ ShutdownExprContext(econtext, true); /* And clean up the memory used */ MemoryContextReset(econtext->ecxt_per_tuple_memory); } /* * Build a per-output-tuple ExprContext for an EState. * * This is normally invoked via GetPerTupleExprContext() macro, * not directly. */ ExprContext * MakePerTupleExprContext(EState *estate) { if (estate->es_per_tuple_exprcontext == NULL) estate->es_per_tuple_exprcontext = CreateExprContext(estate); return estate->es_per_tuple_exprcontext; } /* ---------------------------------------------------------------- * miscellaneous node-init support functions * * Note: all of these are expected to be called with CurrentMemoryContext * equal to the per-query memory context. * ---------------------------------------------------------------- */ /* ---------------- * ExecAssignExprContext * * This initializes the ps_ExprContext field. It is only necessary * to do this for nodes which use ExecQual or ExecProject * because those routines require an econtext. Other nodes that * don't have to evaluate expressions don't need to do this. * ---------------- */ void ExecAssignExprContext(EState *estate, PlanState *planstate) { planstate->ps_ExprContext = CreateExprContext(estate); } /* ---------------- * ExecAssignResultType * ---------------- */ void ExecAssignResultType(PlanState *planstate, TupleDesc tupDesc) { TupleTableSlot *slot = planstate->ps_ResultTupleSlot; ExecSetSlotDescriptor(slot, tupDesc); } /* ---------------- * ExecAssignResultTypeFromTL * ---------------- */ void ExecAssignResultTypeFromTL(PlanState *planstate) { bool hasoid; TupleDesc tupDesc; if (ExecContextForcesOids(planstate, &hasoid)) { /* context forces OID choice; hasoid is now set correctly */ } else { /* given free choice, don't leave space for OIDs in result tuples */ hasoid = false; } /* * ExecTypeFromTL needs the parse-time representation of the tlist, not a * list of ExprStates. This is good because some plan nodes don't bother * to set up planstate->targetlist ... */ tupDesc = ExecTypeFromTL(planstate->plan->targetlist, hasoid); ExecAssignResultType(planstate, tupDesc); } /* ---------------- * ExecGetResultType * ---------------- */ TupleDesc ExecGetResultType(PlanState *planstate) { TupleTableSlot *slot = planstate->ps_ResultTupleSlot; return slot->tts_tupleDescriptor; } /* ---------------- * ExecBuildProjectionInfo * * Build a ProjectionInfo node for evaluating the given tlist in the given * econtext, and storing the result into the tuple slot. (Caller must have * ensured that tuple slot has a descriptor matching the tlist!) Note that * the given tlist should be a list of ExprState nodes, not Expr nodes. * * inputDesc can be NULL, but if it is not, we check to see whether simple * Vars in the tlist match the descriptor. It is important to provide * inputDesc for relation-scan plan nodes, as a cross check that the relation * hasn't been changed since the plan was made. At higher levels of a plan, * there is no need to recheck. * ---------------- */ ProjectionInfo * ExecBuildProjectionInfo(List *targetList, ExprContext *econtext, TupleTableSlot *slot, TupleDesc inputDesc) { ProjectionInfo *projInfo = makeNode(ProjectionInfo); int len = ExecTargetListLength(targetList); int *workspace; int *varSlotOffsets; int *varNumbers; int *varOutputCols; List *exprlist; int numSimpleVars; bool directMap; ListCell *tl; projInfo->pi_exprContext = econtext; projInfo->pi_slot = slot; /* since these are all int arrays, we need do just one palloc */ workspace = (int *) palloc(len * 3 * sizeof(int)); projInfo->pi_varSlotOffsets = varSlotOffsets = workspace; projInfo->pi_varNumbers = varNumbers = workspace + len; projInfo->pi_varOutputCols = varOutputCols = workspace + len * 2; projInfo->pi_lastInnerVar = 0; projInfo->pi_lastOuterVar = 0; projInfo->pi_lastScanVar = 0; /* * We separate the target list elements into simple Var references and * expressions which require the full ExecTargetList machinery. To be a * simple Var, a Var has to be a user attribute and not mismatch the * inputDesc. (Note: if there is a type mismatch then ExecEvalVar will * probably throw an error at runtime, but we leave that to it.) */ exprlist = NIL; numSimpleVars = 0; directMap = true; foreach(tl, targetList) { GenericExprState *gstate = (GenericExprState *) lfirst(tl); Var *variable = (Var *) gstate->arg->expr; bool isSimpleVar = false; if (variable != NULL && IsA(variable, Var) && variable->varattno > 0) { if (!inputDesc) isSimpleVar = true; /* can't check type, assume OK */ else if (variable->varattno <= inputDesc->natts) { Form_pg_attribute attr; attr = inputDesc->attrs[variable->varattno - 1]; if (!attr->attisdropped && variable->vartype == attr->atttypid) isSimpleVar = true; } } if (isSimpleVar) { TargetEntry *tle = (TargetEntry *) gstate->xprstate.expr; AttrNumber attnum = variable->varattno; varNumbers[numSimpleVars] = attnum; varOutputCols[numSimpleVars] = tle->resno; if (tle->resno != numSimpleVars + 1) directMap = false; switch (variable->varno) { case INNER: varSlotOffsets[numSimpleVars] = offsetof(ExprContext, ecxt_innertuple); if (projInfo->pi_lastInnerVar < attnum) projInfo->pi_lastInnerVar = attnum; break; case OUTER: varSlotOffsets[numSimpleVars] = offsetof(ExprContext, ecxt_outertuple); if (projInfo->pi_lastOuterVar < attnum) projInfo->pi_lastOuterVar = attnum; break; default: varSlotOffsets[numSimpleVars] = offsetof(ExprContext, ecxt_scantuple); if (projInfo->pi_lastScanVar < attnum) projInfo->pi_lastScanVar = attnum; break; } numSimpleVars++; } else { /* Not a simple variable, add it to generic targetlist */ exprlist = lappend(exprlist, gstate); /* Examine expr to include contained Vars in lastXXXVar counts */ get_last_attnums((Node *) variable, projInfo); } } projInfo->pi_targetlist = exprlist; projInfo->pi_numSimpleVars = numSimpleVars; projInfo->pi_directMap = directMap; if (exprlist == NIL) projInfo->pi_itemIsDone = NULL; /* not needed */ else projInfo->pi_itemIsDone = (ExprDoneCond *) palloc(len * sizeof(ExprDoneCond)); return projInfo; } /* * get_last_attnums: expression walker for ExecBuildProjectionInfo * * Update the lastXXXVar counts to be at least as large as the largest * attribute numbers found in the expression */ static bool get_last_attnums(Node *node, ProjectionInfo *projInfo) { if (node == NULL) return false; if (IsA(node, Var)) { Var *variable = (Var *) node; AttrNumber attnum = variable->varattno; switch (variable->varno) { case INNER: if (projInfo->pi_lastInnerVar < attnum) projInfo->pi_lastInnerVar = attnum; break; case OUTER: if (projInfo->pi_lastOuterVar < attnum) projInfo->pi_lastOuterVar = attnum; break; default: if (projInfo->pi_lastScanVar < attnum) projInfo->pi_lastScanVar = attnum; break; } return false; } /* * Don't examine the arguments of Aggrefs or WindowFuncs, because those do * not represent expressions to be evaluated within the overall * targetlist's econtext. */ if (IsA(node, Aggref)) return false; if (IsA(node, WindowFunc)) return false; return expression_tree_walker(node, get_last_attnums, (void *) projInfo); } /* ---------------- * ExecAssignProjectionInfo * * forms the projection information from the node's targetlist * * Notes for inputDesc are same as for ExecBuildProjectionInfo: supply it * for a relation-scan node, can pass NULL for upper-level nodes * ---------------- */ void ExecAssignProjectionInfo(PlanState *planstate, TupleDesc inputDesc) { planstate->ps_ProjInfo = ExecBuildProjectionInfo(planstate->targetlist, planstate->ps_ExprContext, planstate->ps_ResultTupleSlot, inputDesc); } /* ---------------- * ExecFreeExprContext * * A plan node's ExprContext should be freed explicitly during executor * shutdown because there may be shutdown callbacks to call. (Other resources * made by the above routines, such as projection info, don't need to be freed * explicitly because they're just memory in the per-query memory context.) * * However ... there is no particular need to do it during ExecEndNode, * because FreeExecutorState will free any remaining ExprContexts within * the EState. Letting FreeExecutorState do it allows the ExprContexts to * be freed in reverse order of creation, rather than order of creation as * will happen if we delete them here, which saves O(N^2) work in the list * cleanup inside FreeExprContext. * ---------------- */ void ExecFreeExprContext(PlanState *planstate) { /* * Per above discussion, don't actually delete the ExprContext. We do * unlink it from the plan node, though. */ planstate->ps_ExprContext = NULL; } /* ---------------------------------------------------------------- * the following scan type support functions are for * those nodes which are stubborn and return tuples in * their Scan tuple slot instead of their Result tuple * slot.. luck fur us, these nodes do not do projections * so we don't have to worry about getting the ProjectionInfo * right for them... -cim 6/3/91 * ---------------------------------------------------------------- */ /* ---------------- * ExecGetScanType * ---------------- */ TupleDesc ExecGetScanType(ScanState *scanstate) { TupleTableSlot *slot = scanstate->ss_ScanTupleSlot; return slot->tts_tupleDescriptor; } /* ---------------- * ExecAssignScanType * ---------------- */ void ExecAssignScanType(ScanState *scanstate, TupleDesc tupDesc) { TupleTableSlot *slot = scanstate->ss_ScanTupleSlot; ExecSetSlotDescriptor(slot, tupDesc); } /* ---------------- * ExecAssignScanTypeFromOuterPlan * ---------------- */ void ExecAssignScanTypeFromOuterPlan(ScanState *scanstate) { PlanState *outerPlan; TupleDesc tupDesc; outerPlan = outerPlanState(scanstate); tupDesc = ExecGetResultType(outerPlan); ExecAssignScanType(scanstate, tupDesc); } /* ---------------------------------------------------------------- * Scan node support * ---------------------------------------------------------------- */ /* ---------------------------------------------------------------- * ExecRelationIsTargetRelation * * Detect whether a relation (identified by rangetable index) * is one of the target relations of the query. * ---------------------------------------------------------------- */ bool ExecRelationIsTargetRelation(EState *estate, Index scanrelid) { ResultRelInfo *resultRelInfos; int i; resultRelInfos = estate->es_result_relations; for (i = 0; i < estate->es_num_result_relations; i++) { if (resultRelInfos[i].ri_RangeTableIndex == scanrelid) return true; } return false; } /* ---------------------------------------------------------------- * ExecOpenScanRelation * * Open the heap relation to be scanned by a base-level scan plan node. * This should be called during the node's ExecInit routine. * * By default, this acquires AccessShareLock on the relation. However, * if the relation was already locked by InitPlan, we don't need to acquire * any additional lock. This saves trips to the shared lock manager. * ---------------------------------------------------------------- */ Relation ExecOpenScanRelation(EState *estate, Index scanrelid) { Oid reloid; LOCKMODE lockmode; /* * Determine the lock type we need. First, scan to see if target relation * is a result relation. If not, check if it's a FOR UPDATE/FOR SHARE * relation. In either of those cases, we got the lock already. */ lockmode = AccessShareLock; if (ExecRelationIsTargetRelation(estate, scanrelid)) lockmode = NoLock; else { ListCell *l; foreach(l, estate->es_rowMarks) { ExecRowMark *erm = lfirst(l); if (erm->rti == scanrelid) { lockmode = NoLock; break; } } } /* OK, open the relation and acquire lock as needed */ reloid = getrelid(scanrelid, estate->es_range_table); return heap_open(reloid, lockmode); } /* ---------------------------------------------------------------- * ExecCloseScanRelation * * Close the heap relation scanned by a base-level scan plan node. * This should be called during the node's ExecEnd routine. * * Currently, we do not release the lock acquired by ExecOpenScanRelation. * This lock should be held till end of transaction. (There is a faction * that considers this too much locking, however.) * * If we did want to release the lock, we'd have to repeat the logic in * ExecOpenScanRelation in order to figure out what to release. * ---------------------------------------------------------------- */ void ExecCloseScanRelation(Relation scanrel) { heap_close(scanrel, NoLock); } /* ---------------------------------------------------------------- * ExecInsertIndexTuples support * ---------------------------------------------------------------- */ /* ---------------------------------------------------------------- * ExecOpenIndices * * Find the indices associated with a result relation, open them, * and save information about them in the result ResultRelInfo. * * At entry, caller has already opened and locked * resultRelInfo->ri_RelationDesc. * ---------------------------------------------------------------- */ void ExecOpenIndices(ResultRelInfo *resultRelInfo) { Relation resultRelation = resultRelInfo->ri_RelationDesc; List *indexoidlist; ListCell *l; int len, i; RelationPtr relationDescs; IndexInfo **indexInfoArray; resultRelInfo->ri_NumIndices = 0; /* fast path if no indexes */ if (!RelationGetForm(resultRelation)->relhasindex) return; /* * Get cached list of index OIDs */ indexoidlist = RelationGetIndexList(resultRelation); len = list_length(indexoidlist); if (len == 0) return; /* * allocate space for result arrays */ relationDescs = (RelationPtr) palloc(len * sizeof(Relation)); indexInfoArray = (IndexInfo **) palloc(len * sizeof(IndexInfo *)); resultRelInfo->ri_NumIndices = len; resultRelInfo->ri_IndexRelationDescs = relationDescs; resultRelInfo->ri_IndexRelationInfo = indexInfoArray; /* * For each index, open the index relation and save pg_index info. We * acquire RowExclusiveLock, signifying we will update the index. */ i = 0; foreach(l, indexoidlist) { Oid indexOid = lfirst_oid(l); Relation indexDesc; IndexInfo *ii; indexDesc = index_open(indexOid, RowExclusiveLock); /* extract index key information from the index's pg_index info */ ii = BuildIndexInfo(indexDesc); relationDescs[i] = indexDesc; indexInfoArray[i] = ii; i++; } list_free(indexoidlist); } /* ---------------------------------------------------------------- * ExecCloseIndices * * Close the index relations stored in resultRelInfo * ---------------------------------------------------------------- */ void ExecCloseIndices(ResultRelInfo *resultRelInfo) { int i; int numIndices; RelationPtr indexDescs; numIndices = resultRelInfo->ri_NumIndices; indexDescs = resultRelInfo->ri_IndexRelationDescs; for (i = 0; i < numIndices; i++) { if (indexDescs[i] == NULL) continue; /* shouldn't happen? */ /* Drop lock acquired by ExecOpenIndices */ index_close(indexDescs[i], RowExclusiveLock); } /* * XXX should free indexInfo array here too? Currently we assume that * such stuff will be cleaned up automatically in FreeExecutorState. */ } /* ---------------------------------------------------------------- * ExecInsertIndexTuples * * This routine takes care of inserting index tuples * into all the relations indexing the result relation * when a heap tuple is inserted into the result relation. * Much of this code should be moved into the genam * stuff as it only exists here because the genam stuff * doesn't provide the functionality needed by the * executor.. -cim 9/27/89 * * This returns a list of index OIDs for any unique or exclusion * constraints that are deferred and that had * potential (unconfirmed) conflicts. * * CAUTION: this must not be called for a HOT update. * We can't defend against that here for lack of info. * Should we change the API to make it safer? * ---------------------------------------------------------------- */ List * ExecInsertIndexTuples(TupleTableSlot *slot, ItemPointer tupleid, EState *estate) { List *result = NIL; ResultRelInfo *resultRelInfo; int i; int numIndices; RelationPtr relationDescs; Relation heapRelation; IndexInfo **indexInfoArray; ExprContext *econtext; Datum values[INDEX_MAX_KEYS]; bool isnull[INDEX_MAX_KEYS]; /* * Get information from the result relation info structure. */ resultRelInfo = estate->es_result_relation_info; numIndices = resultRelInfo->ri_NumIndices; relationDescs = resultRelInfo->ri_IndexRelationDescs; indexInfoArray = resultRelInfo->ri_IndexRelationInfo; heapRelation = resultRelInfo->ri_RelationDesc; /* * We will use the EState's per-tuple context for evaluating predicates * and index 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; /* * for each index, form and insert the index tuple */ for (i = 0; i < numIndices; i++) { Relation indexRelation = relationDescs[i]; IndexInfo *indexInfo; IndexUniqueCheck checkUnique; bool satisfiesConstraint; if (indexRelation == NULL) continue; indexInfo = indexInfoArray[i]; /* If the index is marked as read-only, ignore it */ if (!indexInfo->ii_ReadyForInserts) continue; /* Check for partial index */ if (indexInfo->ii_Predicate != NIL) { List *predicate; /* * If predicate state not set up yet, create it (in the estate's * per-query context) */ predicate = indexInfo->ii_PredicateState; if (predicate == NIL) { predicate = (List *) ExecPrepareExpr((Expr *) indexInfo->ii_Predicate, estate); indexInfo->ii_PredicateState = predicate; } /* Skip this index-update if the predicate isn't satisfied */ if (!ExecQual(predicate, econtext, false)) continue; } /* * FormIndexDatum fills in its values and isnull parameters with the * appropriate values for the column(s) of the index. */ FormIndexDatum(indexInfo, slot, estate, values, isnull); /* * The index AM does the actual insertion, plus uniqueness checking. * * For an immediate-mode unique index, we just tell the index AM to * throw error if not unique. * * For a deferrable unique index, we tell the index AM to just detect * possible non-uniqueness, and we add the index OID to the result * list if further checking is needed. */ if (!indexRelation->rd_index->indisunique) checkUnique = UNIQUE_CHECK_NO; else if (indexRelation->rd_index->indimmediate) checkUnique = UNIQUE_CHECK_YES; else checkUnique = UNIQUE_CHECK_PARTIAL; satisfiesConstraint = index_insert(indexRelation, /* index relation */ values, /* array of index Datums */ isnull, /* null flags */ tupleid, /* tid of heap tuple */ heapRelation, /* heap relation */ checkUnique); /* type of uniqueness check to do */ /* * If the index has an associated exclusion constraint, check that. * This is simpler than the process for uniqueness checks since we * always insert first and then check. If the constraint is deferred, * we check now anyway, but don't throw error on violation; instead * we'll queue a recheck event. * * An index for an exclusion constraint can't also be UNIQUE (not an * essential property, we just don't allow it in the grammar), so no * need to preserve the prior state of satisfiesConstraint. */ if (indexInfo->ii_ExclusionOps != NULL) { bool errorOK = !indexRelation->rd_index->indimmediate; satisfiesConstraint = check_exclusion_constraint(heapRelation, indexRelation, indexInfo, tupleid, values, isnull, estate, false, errorOK); } if ((checkUnique == UNIQUE_CHECK_PARTIAL || indexInfo->ii_ExclusionOps != NULL) && !satisfiesConstraint) { /* * The tuple potentially violates the uniqueness or exclusion * constraint, so make a note of the index so that we can re-check * it later. */ result = lappend_oid(result, RelationGetRelid(indexRelation)); } } return result; } /* * Check for violation of an exclusion constraint * * heap: the table containing the new tuple * index: the index supporting the exclusion constraint * indexInfo: info about the index, including the exclusion properties * tupleid: heap TID of the new tuple we have just inserted * values, isnull: the *index* column values computed for the new tuple * estate: an EState we can do evaluation in * newIndex: if true, we are trying to build a new index (this affects * only the wording of error messages) * errorOK: if true, don't throw error for violation * * Returns true if OK, false if actual or potential violation * * When errorOK is true, we report violation without waiting to see if any * concurrent transaction has committed or not; so the violation is only * potential, and the caller must recheck sometime later. This behavior * is convenient for deferred exclusion checks; we need not bother queuing * a deferred event if there is definitely no conflict at insertion time. * * When errorOK is false, we'll throw error on violation, so a false result * is impossible. */ bool check_exclusion_constraint(Relation heap, Relation index, IndexInfo *indexInfo, ItemPointer tupleid, Datum *values, bool *isnull, EState *estate, bool newIndex, bool errorOK) { Oid *constr_procs = indexInfo->ii_ExclusionProcs; uint16 *constr_strats = indexInfo->ii_ExclusionStrats; int index_natts = index->rd_index->indnatts; IndexScanDesc index_scan; HeapTuple tup; ScanKeyData scankeys[INDEX_MAX_KEYS]; SnapshotData DirtySnapshot; int i; bool conflict; bool found_self; ExprContext *econtext; TupleTableSlot *existing_slot; TupleTableSlot *save_scantuple; /* * If any of the input values are NULL, the constraint check is assumed to * pass (i.e., we assume the operators are strict). */ for (i = 0; i < index_natts; i++) { if (isnull[i]) return true; } /* * Search the tuples that are in the index for any violations, including * tuples that aren't visible yet. */ InitDirtySnapshot(DirtySnapshot); for (i = 0; i < index_natts; i++) { ScanKeyInit(&scankeys[i], i + 1, constr_strats[i], constr_procs[i], values[i]); } /* * Need a TupleTableSlot to put existing tuples in. * * To use FormIndexDatum, we have to make the econtext's scantuple point * to this slot. Be sure to save and restore caller's value for * scantuple. */ existing_slot = MakeSingleTupleTableSlot(RelationGetDescr(heap)); econtext = GetPerTupleExprContext(estate); save_scantuple = econtext->ecxt_scantuple; econtext->ecxt_scantuple = existing_slot; /* * May have to restart scan from this point if a potential conflict is * found. */ retry: conflict = false; found_self = false; index_scan = index_beginscan(heap, index, &DirtySnapshot, index_natts, 0); index_rescan(index_scan, scankeys, index_natts, NULL, 0); while ((tup = index_getnext(index_scan, ForwardScanDirection)) != NULL) { TransactionId xwait; Datum existing_values[INDEX_MAX_KEYS]; bool existing_isnull[INDEX_MAX_KEYS]; char *error_new; char *error_existing; /* * Ignore the entry for the tuple we're trying to check. */ if (ItemPointerEquals(tupleid, &tup->t_self)) { if (found_self) /* should not happen */ elog(ERROR, "found self tuple multiple times in index \"%s\"", RelationGetRelationName(index)); found_self = true; continue; } /* * Extract the index column values and isnull flags from the existing * tuple. */ ExecStoreTuple(tup, existing_slot, InvalidBuffer, false); FormIndexDatum(indexInfo, existing_slot, estate, existing_values, existing_isnull); /* If lossy indexscan, must recheck the condition */ if (index_scan->xs_recheck) { if (!index_recheck_constraint(index, constr_procs, existing_values, existing_isnull, values)) continue; /* tuple doesn't actually match, so no * conflict */ } /* * At this point we have either a conflict or a potential conflict. If * we're not supposed to raise error, just return the fact of the * potential conflict without waiting to see if it's real. */ if (errorOK) { conflict = true; break; } /* * If an in-progress transaction is affecting the visibility of this * tuple, we need to wait for it to complete and then recheck. For * simplicity we do rechecking by just restarting the whole scan --- * this case probably doesn't happen often enough to be worth trying * harder, and anyway we don't want to hold any index internal locks * while waiting. */ xwait = TransactionIdIsValid(DirtySnapshot.xmin) ? DirtySnapshot.xmin : DirtySnapshot.xmax; if (TransactionIdIsValid(xwait)) { index_endscan(index_scan); XactLockTableWait(xwait); goto retry; } /* * We have a definite conflict. Report it. */ error_new = BuildIndexValueDescription(index, values, isnull); error_existing = BuildIndexValueDescription(index, existing_values, existing_isnull); if (newIndex) ereport(ERROR, (errcode(ERRCODE_EXCLUSION_VIOLATION), errmsg("could not create exclusion constraint \"%s\"", RelationGetRelationName(index)), errdetail("Key %s conflicts with key %s.", error_new, error_existing))); else ereport(ERROR, (errcode(ERRCODE_EXCLUSION_VIOLATION), errmsg("conflicting key value violates exclusion constraint \"%s\"", RelationGetRelationName(index)), errdetail("Key %s conflicts with existing key %s.", error_new, error_existing))); } index_endscan(index_scan); /* * Ordinarily, at this point the search should have found the originally * inserted tuple, unless we exited the loop early because of conflict. * However, it is possible to define exclusion constraints for which * that wouldn't be true --- for instance, if the operator is <>. * So we no longer complain if found_self is still false. */ econtext->ecxt_scantuple = save_scantuple; ExecDropSingleTupleTableSlot(existing_slot); return !conflict; } /* * Check existing tuple's index values to see if it really matches the * exclusion condition against the new_values. Returns true if conflict. */ static bool index_recheck_constraint(Relation index, Oid *constr_procs, Datum *existing_values, bool *existing_isnull, Datum *new_values) { int index_natts = index->rd_index->indnatts; int i; for (i = 0; i < index_natts; i++) { /* Assume the exclusion operators are strict */ if (existing_isnull[i]) return false; if (!DatumGetBool(OidFunctionCall2(constr_procs[i], existing_values[i], new_values[i]))) return false; } return true; } /* * UpdateChangedParamSet * Add changed parameters to a plan node's chgParam set */ void UpdateChangedParamSet(PlanState *node, Bitmapset *newchg) { Bitmapset *parmset; /* * The plan node only depends on params listed in its allParam set. Don't * include anything else into its chgParam set. */ parmset = bms_intersect(node->plan->allParam, newchg); /* * Keep node->chgParam == NULL if there's not actually any members; this * allows the simplest possible tests in executor node files. */ if (!bms_is_empty(parmset)) node->chgParam = bms_join(node->chgParam, parmset); else bms_free(parmset); } /* * Register a shutdown callback in an ExprContext. * * Shutdown callbacks will be called (in reverse order of registration) * when the ExprContext is deleted or rescanned. This provides a hook * for functions called in the context to do any cleanup needed --- it's * particularly useful for functions returning sets. Note that the * callback will *not* be called in the event that execution is aborted * by an error. */ void RegisterExprContextCallback(ExprContext *econtext, ExprContextCallbackFunction function, Datum arg) { ExprContext_CB *ecxt_callback; /* Save the info in appropriate memory context */ ecxt_callback = (ExprContext_CB *) MemoryContextAlloc(econtext->ecxt_per_query_memory, sizeof(ExprContext_CB)); ecxt_callback->function = function; ecxt_callback->arg = arg; /* link to front of list for appropriate execution order */ ecxt_callback->next = econtext->ecxt_callbacks; econtext->ecxt_callbacks = ecxt_callback; } /* * Deregister a shutdown callback in an ExprContext. * * Any list entries matching the function and arg will be removed. * This can be used if it's no longer necessary to call the callback. */ void UnregisterExprContextCallback(ExprContext *econtext, ExprContextCallbackFunction function, Datum arg) { ExprContext_CB **prev_callback; ExprContext_CB *ecxt_callback; prev_callback = &econtext->ecxt_callbacks; while ((ecxt_callback = *prev_callback) != NULL) { if (ecxt_callback->function == function && ecxt_callback->arg == arg) { *prev_callback = ecxt_callback->next; pfree(ecxt_callback); } else prev_callback = &ecxt_callback->next; } } /* * Call all the shutdown callbacks registered in an ExprContext. * * The callback list is emptied (important in case this is only a rescan * reset, and not deletion of the ExprContext). * * If isCommit is false, just clean the callback list but don't call 'em. * (See comment for FreeExprContext.) */ static void ShutdownExprContext(ExprContext *econtext, bool isCommit) { ExprContext_CB *ecxt_callback; MemoryContext oldcontext; /* Fast path in normal case where there's nothing to do. */ if (econtext->ecxt_callbacks == NULL) return; /* * Call the callbacks in econtext's per-tuple context. This ensures that * any memory they might leak will get cleaned up. */ oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory); /* * Call each callback function in reverse registration order. */ while ((ecxt_callback = econtext->ecxt_callbacks) != NULL) { econtext->ecxt_callbacks = ecxt_callback->next; if (isCommit) (*ecxt_callback->function) (ecxt_callback->arg); pfree(ecxt_callback); } MemoryContextSwitchTo(oldcontext); }