/*------------------------------------------------------------------------- * * execUtils.c * miscellaneous executor utility routines * * Portions Copyright (c) 1996-2017, 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 * * RegisterExprContextCallback Register function shutdown callback * UnregisterExprContextCallback Deregister function shutdown callback * * GetAttributeByName Runtime extraction of columns from tuples. * GetAttributeByNum * * 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/relscan.h" #include "access/transam.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "parser/parsetree.h" #include "storage/lmgr.h" #include "utils/builtins.h" #include "utils/memutils.h" #include "utils/rel.h" #include "utils/typcache.h" 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_SIZES); /* * 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 = InvalidSnapshot; /* caller must initialize this */ 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_trig_newtup_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_top_eflags = 0; estate->es_instrument = 0; estate->es_finished = false; estate->es_exprcontexts = NIL; estate->es_subplanstates = NIL; estate->es_auxmodifytables = NIL; estate->es_per_tuple_exprcontext = NULL; estate->es_epqTuple = NULL; estate->es_epqTupleSet = NULL; estate->es_epqScanDone = NULL; estate->es_sourceText = 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_SIZES); 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_SIZES); 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; } /* ---------------- * 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->plan->targetlist, planstate->ps_ExprContext, planstate->ps_ResultTupleSlot, planstate, 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 * ---------------------------------------------------------------- */ /* ---------------- * 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, int eflags) { Relation rel; 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 { /* Keep this check in sync with InitPlan! */ ExecRowMark *erm = ExecFindRowMark(estate, scanrelid, true); if (erm != NULL && erm->relation != NULL) lockmode = NoLock; } /* Open the relation and acquire lock as needed */ reloid = getrelid(scanrelid, estate->es_range_table); rel = heap_open(reloid, lockmode); /* * Complain if we're attempting a scan of an unscannable relation, except * when the query won't actually be run. This is a slightly klugy place * to do this, perhaps, but there is no better place. */ if ((eflags & (EXEC_FLAG_EXPLAIN_ONLY | EXEC_FLAG_WITH_NO_DATA)) == 0 && !RelationIsScannable(rel)) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("materialized view \"%s\" has not been populated", RelationGetRelationName(rel)), errhint("Use the REFRESH MATERIALIZED VIEW command."))); return rel; } /* ---------------------------------------------------------------- * 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); } /* * 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); } /* * ExecLockNonLeafAppendTables * * Locks, if necessary, the tables indicated by the RT indexes contained in * the partitioned_rels list. These are the non-leaf tables in the partition * tree controlled by a given Append or MergeAppend node. */ void ExecLockNonLeafAppendTables(List *partitioned_rels, EState *estate) { PlannedStmt *stmt = estate->es_plannedstmt; ListCell *lc; foreach(lc, partitioned_rels) { ListCell *l; Index rti = lfirst_int(lc); bool is_result_rel = false; Oid relid = getrelid(rti, estate->es_range_table); /* If this is a result relation, already locked in InitPlan */ foreach(l, stmt->nonleafResultRelations) { if (rti == lfirst_int(l)) { is_result_rel = true; break; } } /* * Not a result relation; check if there is a RowMark that requires * taking a RowShareLock on this rel. */ if (!is_result_rel) { PlanRowMark *rc = NULL; foreach(l, stmt->rowMarks) { if (((PlanRowMark *) lfirst(l))->rti == rti) { rc = lfirst(l); break; } } if (rc && RowMarkRequiresRowShareLock(rc->markType)) LockRelationOid(relid, RowShareLock); else LockRelationOid(relid, AccessShareLock); } } } /* * GetAttributeByName * GetAttributeByNum * * These functions return the value of the requested attribute * out of the given tuple Datum. * C functions which take a tuple as an argument are expected * to use these. Ex: overpaid(EMP) might call GetAttributeByNum(). * Note: these are actually rather slow because they do a typcache * lookup on each call. */ Datum GetAttributeByName(HeapTupleHeader tuple, const char *attname, bool *isNull) { AttrNumber attrno; Datum result; Oid tupType; int32 tupTypmod; TupleDesc tupDesc; HeapTupleData tmptup; int i; if (attname == NULL) elog(ERROR, "invalid attribute name"); if (isNull == NULL) elog(ERROR, "a NULL isNull pointer was passed"); if (tuple == NULL) { /* Kinda bogus but compatible with old behavior... */ *isNull = true; return (Datum) 0; } tupType = HeapTupleHeaderGetTypeId(tuple); tupTypmod = HeapTupleHeaderGetTypMod(tuple); tupDesc = lookup_rowtype_tupdesc(tupType, tupTypmod); attrno = InvalidAttrNumber; for (i = 0; i < tupDesc->natts; i++) { if (namestrcmp(&(tupDesc->attrs[i]->attname), attname) == 0) { attrno = tupDesc->attrs[i]->attnum; break; } } if (attrno == InvalidAttrNumber) elog(ERROR, "attribute \"%s\" does not exist", attname); /* * heap_getattr needs a HeapTuple not a bare HeapTupleHeader. We set all * the fields in the struct just in case user tries to inspect system * columns. */ tmptup.t_len = HeapTupleHeaderGetDatumLength(tuple); ItemPointerSetInvalid(&(tmptup.t_self)); tmptup.t_tableOid = InvalidOid; tmptup.t_data = tuple; result = heap_getattr(&tmptup, attrno, tupDesc, isNull); ReleaseTupleDesc(tupDesc); return result; } Datum GetAttributeByNum(HeapTupleHeader tuple, AttrNumber attrno, bool *isNull) { Datum result; Oid tupType; int32 tupTypmod; TupleDesc tupDesc; HeapTupleData tmptup; if (!AttributeNumberIsValid(attrno)) elog(ERROR, "invalid attribute number %d", attrno); if (isNull == NULL) elog(ERROR, "a NULL isNull pointer was passed"); if (tuple == NULL) { /* Kinda bogus but compatible with old behavior... */ *isNull = true; return (Datum) 0; } tupType = HeapTupleHeaderGetTypeId(tuple); tupTypmod = HeapTupleHeaderGetTypMod(tuple); tupDesc = lookup_rowtype_tupdesc(tupType, tupTypmod); /* * heap_getattr needs a HeapTuple not a bare HeapTupleHeader. We set all * the fields in the struct just in case user tries to inspect system * columns. */ tmptup.t_len = HeapTupleHeaderGetDatumLength(tuple); ItemPointerSetInvalid(&(tmptup.t_self)); tmptup.t_tableOid = InvalidOid; tmptup.t_data = tuple; result = heap_getattr(&tmptup, attrno, tupDesc, isNull); ReleaseTupleDesc(tupDesc); return result; } /* * Number of items in a tlist (including any resjunk items!) */ int ExecTargetListLength(List *targetlist) { /* This used to be more complex, but fjoins are dead */ return list_length(targetlist); } /* * Number of items in a tlist, not including any resjunk items */ int ExecCleanTargetListLength(List *targetlist) { int len = 0; ListCell *tl; foreach(tl, targetlist) { TargetEntry *curTle = castNode(TargetEntry, lfirst(tl)); if (!curTle->resjunk) len++; } return len; }