execmain.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	TupleDesc	tupType;

	/*
	 * Do permissions checks.  It's sufficient to examine the query's top
	 * rangetable here --- subplan RTEs will be checked during
	 * ExecInitSubPlan().
	 */
	ExecCheckRTPerms(parseTree->rtable);

	/*
	 * get information from query descriptor
	 */
	rangeTable = parseTree->rtable;

	/*
	 * initialize the node's execution state
	 */
	estate->es_range_table = rangeTable;

	/*
	 * if there is a result relation, initialize result relation stuff
	 */
	if (parseTree->resultRelation != 0 && operation != CMD_SELECT)
	{
		List	   *resultRelations = parseTree->resultRelations;
		int			numResultRelations;
		ResultRelInfo *resultRelInfos;

		if (resultRelations != NIL)
		{
			/*
			 * Multiple result relations (due to inheritance)
			 * parseTree->resultRelations identifies them all
			 */
			ResultRelInfo *resultRelInfo;
			ListCell   *l;

			numResultRelations = list_length(resultRelations);
			resultRelInfos = (ResultRelInfo *)
				palloc(numResultRelations * sizeof(ResultRelInfo));
			resultRelInfo = resultRelInfos;
			foreach(l, resultRelations)
			{
				initResultRelInfo(resultRelInfo,
								  lfirst_int(l),
								  rangeTable,
								  operation,
								  estate->es_instrument);
				resultRelInfo++;
			}
		}
		else
		{
			/*
			 * Single result relation identified by parseTree->resultRelation
			 */
			numResultRelations = 1;
			resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
			initResultRelInfo(resultRelInfos,
							  parseTree->resultRelation,
							  rangeTable,
							  operation,
							  estate->es_instrument);
		}

		estate->es_result_relations = resultRelInfos;
		estate->es_num_result_relations = numResultRelations;
		/* Initialize to first or only result rel */
		estate->es_result_relation_info = resultRelInfos;
	}
	else
	{
		/*
		 * if no result relation, then set state appropriately
		 */
		estate->es_result_relations = NULL;
		estate->es_num_result_relations = 0;
		estate->es_result_relation_info = NULL;
	}

	/*
	 * Detect whether we're doing SELECT INTO.  If so, set the es_into_oids
	 * flag appropriately so that the plan tree will be initialized with the
	 * correct tuple descriptors.
	 */
	do_select_into = false;

	if (operation == CMD_SELECT && parseTree->into != NULL)
	{
		do_select_into = true;
		estate->es_select_into = true;
		estate->es_into_oids = parseTree->intoHasOids;
	}

	/*
	 * Have to lock relations selected FOR UPDATE/FOR SHARE
	 */
	estate->es_rowMarks = NIL;
	estate->es_forUpdate = parseTree->forUpdate;
	estate->es_rowNoWait = parseTree->rowNoWait;
	if (parseTree->rowMarks != NIL)
	{
		ListCell   *l;

		foreach(l, parseTree->rowMarks)
		{
			Index		rti = lfirst_int(l);
			Oid			relid = getrelid(rti, rangeTable);
			Relation	relation;
			execRowMark *erm;

			relation = heap_open(relid, RowShareLock);
			erm = (execRowMark *) palloc(sizeof(execRowMark));
			erm->relation = relation;
			erm->rti = rti;
			snprintf(erm->resname, sizeof(erm->resname), "ctid%u", rti);
			estate->es_rowMarks = lappend(estate->es_rowMarks, erm);
		}
	}

	/*
	 * initialize the executor "tuple" table.  We need slots for all the plan
	 * nodes, plus possibly output slots for the junkfilter(s). At this point
	 * we aren't sure if we need junkfilters, so just add slots for them
	 * unconditionally.  Also, if it's not a SELECT, set up a slot for use for
	 * trigger output tuples.
	 */
	{
		int			nSlots = ExecCountSlotsNode(plan);

		if (parseTree->resultRelations != NIL)
			nSlots += list_length(parseTree->resultRelations);
		else
			nSlots += 1;
		if (operation != CMD_SELECT)
			nSlots++;

		estate->es_tupleTable = ExecCreateTupleTable(nSlots);

		if (operation != CMD_SELECT)
			estate->es_trig_tuple_slot =
				ExecAllocTableSlot(estate->es_tupleTable);
	}

	/* mark EvalPlanQual not active */
	estate->es_topPlan = plan;
	estate->es_evalPlanQual = NULL;
	estate->es_evTupleNull = NULL;
	estate->es_evTuple = NULL;
	estate->es_useEvalPlan = false;

	/*
	 * initialize the private state information for all the nodes in the query
	 * tree.  This opens files, allocates storage and leaves us ready to start
	 * processing tuples.
	 */
	planstate = ExecInitNode(plan, estate);

	/*
	 * Get the tuple descriptor describing the type of tuples to return. (this
	 * is especially important if we are creating a relation with "SELECT
	 * INTO")
	 */
	tupType = ExecGetResultType(planstate);

	/*
	 * Initialize the junk filter if needed.  SELECT and INSERT queries need a
	 * filter if there are any junk attrs in the tlist.  INSERT and SELECT
	 * INTO also need a filter if the plan may return raw disk tuples (else
	 * heap_insert will be scribbling on the source relation!). UPDATE and
	 * DELETE always need a filter, since there's always a junk 'ctid'
	 * attribute present --- no need to look first.
	 */
	{
		bool		junk_filter_needed = false;
		ListCell   *tlist;

		switch (operation)
		{
			case CMD_SELECT:
			case CMD_INSERT:
				foreach(tlist, plan->targetlist)
				{
					TargetEntry *tle = (TargetEntry *) lfirst(tlist);

					if (tle->resjunk)
					{
						junk_filter_needed = true;
						break;
					}
				}
				if (!junk_filter_needed &&
					(operation == CMD_INSERT || do_select_into) &&
					ExecMayReturnRawTuples(planstate))
					junk_filter_needed = true;
				break;
			case CMD_UPDATE:
			case CMD_DELETE:
				junk_filter_needed = true;
				break;
			default:
				break;
		}

		if (junk_filter_needed)
		{
			/*
			 * If there are multiple result relations, each one needs its own
			 * junk filter.  Note this is only possible for UPDATE/DELETE, so
			 * we can't be fooled by some needing a filter and some not.
			 */
			if (parseTree->resultRelations != NIL)
			{
				PlanState **appendplans;
				int			as_nplans;
				ResultRelInfo *resultRelInfo;
				int			i;

				/* Top plan had better be an Append here. */
				Assert(IsA(plan, Append));
				Assert(((Append *) plan)->isTarget);
				Assert(IsA(planstate, AppendState));
				appendplans = ((AppendState *) planstate)->appendplans;
				as_nplans = ((AppendState *) planstate)->as_nplans;
				Assert(as_nplans == estate->es_num_result_relations);
				resultRelInfo = estate->es_result_relations;
				for (i = 0; i < as_nplans; i++)
				{
					PlanState  *subplan = appendplans[i];
					JunkFilter *j;

					j = ExecInitJunkFilter(subplan->plan->targetlist,
							resultRelInfo->ri_RelationDesc->rd_att->tdhasoid,
								  ExecAllocTableSlot(estate->es_tupleTable));
					resultRelInfo->ri_junkFilter = j;
					resultRelInfo++;
				}

				/*
				 * Set active junkfilter too; at this point ExecInitAppend has
				 * already selected an active result relation...
				 */
				estate->es_junkFilter =
					estate->es_result_relation_info->ri_junkFilter;
			}
			else
			{
				/* Normal case with just one JunkFilter */
				JunkFilter *j;

				j = ExecInitJunkFilter(planstate->plan->targetlist,
									   tupType->tdhasoid,
								  ExecAllocTableSlot(estate->es_tupleTable));
				estate->es_junkFilter = j;
				if (estate->es_result_relation_info)
					estate->es_result_relation_info->ri_junkFilter = j;

				/* For SELECT, want to return the cleaned tuple type */
				if (operation == CMD_SELECT)
					tupType = j->jf_cleanTupType;
			}
		}
		else
			estate->es_junkFilter = NULL;
	}

	/*
	 * If doing SELECT INTO, initialize the "into" relation.  We must wait
	 * till now so we have the "clean" result tuple type to create the new
	 * table from.
	 *
	 * If EXPLAIN, skip creating the "into" relation.
	 */
	intoRelationDesc = NULL;

	if (do_select_into && !explainOnly)
	{
		char	   *intoName;
		Oid			namespaceId;
		Oid			tablespaceId;
		AclResult	aclresult;
		Oid			intoRelationId;
		TupleDesc	tupdesc;

		/*
		 * find namespace to create in, check permissions
		 */
		intoName = parseTree->into->relname;
		namespaceId = RangeVarGetCreationNamespace(parseTree->into);

		aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
										  ACL_CREATE);
		if (aclresult != ACLCHECK_OK)
			aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
						   get_namespace_name(namespaceId));

		tablespaceId = GetDefaultTablespace();
		if (OidIsValid(tablespaceId)) {
			aclresult = pg_tablespace_aclcheck(tablespaceId, GetUserId(),
											   ACL_CREATE);

			if (aclresult != ACLCHECK_OK)
				aclcheck_error(aclresult, ACL_KIND_TABLESPACE,
							   get_tablespace_name(tablespaceId));
		}

		/*
		 * have to copy tupType to get rid of constraints
		 */
		tupdesc = CreateTupleDescCopy(tupType);

		intoRelationId = heap_create_with_catalog(intoName,
												  namespaceId,
												  tablespaceId,
												  InvalidOid,
												  GetUserId(),
												  tupdesc,
												  RELKIND_RELATION,
												  false,
												  true,
												  0,
												  ONCOMMIT_NOOP,
												  allowSystemTableMods);

		FreeTupleDesc(tupdesc);

		/*
		 * Advance command counter so that the newly-created relation's
		 * catalog tuples will be visible to heap_open.
		 */
		CommandCounterIncrement();

		/*
		 * If necessary, create a TOAST table for the into relation. Note that
		 * AlterTableCreateToastTable ends with CommandCounterIncrement(), so
		 * that the TOAST table will be visible for insertion.
		 */
		AlterTableCreateToastTable(intoRelationId, true);

		/*
		 * And open the constructed table for writing.
		 */
		intoRelationDesc = heap_open(intoRelationId, AccessExclusiveLock);

		/* use_wal off requires rd_targblock be initially invalid */
		Assert(intoRelationDesc->rd_targblock == InvalidBlockNumber);

		/*
		 * We can skip WAL-logging the insertions, unless PITR is in use.
		 *
		 * Note that for a non-temp INTO table, this is safe only because we
		 * know that the catalog changes above will have been WAL-logged, and
		 * so RecordTransactionCommit will think it needs to WAL-log the
		 * eventual transaction commit.  Else the commit might be lost, even
		 * though all the data is safely fsync'd ...
		 */
		estate->es_into_relation_use_wal = XLogArchivingActive();
	}

	estate->es_into_relation_descriptor = intoRelationDesc;

	queryDesc->tupDesc = tupType;
	queryDesc->planstate = planstate;
}

/*
 * Initialize ResultRelInfo data for one result relation
 */
static void
initResultRelInfo(ResultRelInfo *resultRelInfo,
				  Index resultRelationIndex,
				  List *rangeTable,
				  CmdType operation,
				  bool doInstrument)
{
	Oid			resultRelationOid;
	Relation	resultRelationDesc;

	resultRelationOid = getrelid(resultRelationIndex, rangeTable);
	resultRelationDesc = heap_open(resultRelationOid, RowExclusiveLock);

	switch (resultRelationDesc->rd_rel->relkind)
	{
		case RELKIND_SEQUENCE:
			ereport(ERROR,
					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
					 errmsg("cannot change sequence \"%s\"",
							RelationGetRelationName(resultRelationDesc))));
			break;
		case RELKIND_TOASTVALUE:
			ereport(ERROR,
					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
					 errmsg("cannot change TOAST relation \"%s\"",
							RelationGetRelationName(resultRelationDesc))));
			break;
		case RELKIND_VIEW:
			ereport(ERROR,
					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
					 errmsg("cannot change view \"%s\"",
							RelationGetRelationName(resultRelationDesc))));
			break;
	}

	MemSet(resultRelInfo, 0, sizeof(ResultRelInfo));
	resultRelInfo->type = T_ResultRelInfo;
	resultRelInfo->ri_RangeTableIndex = resultRelationIndex;
	resultRelInfo->ri_RelationDesc = resultRelationDesc;
	resultRelInfo->ri_NumIndices = 0;
	resultRelInfo->ri_IndexRelationDescs = NULL;
	resultRelInfo->ri_IndexRelationInfo = NULL;
	/* make a copy so as not to depend on relcache info not changing... */
	resultRelInfo->ri_TrigDesc = CopyTriggerDesc(resultRelationDesc->trigdesc);
	if (resultRelInfo->ri_TrigDesc)
	{
		int			n = resultRelInfo->ri_TrigDesc->numtriggers;

		resultRelInfo->ri_TrigFunctions = (FmgrInfo *)
			palloc0(n * sizeof(FmgrInfo));
		if (doInstrument)
			resultRelInfo->ri_TrigInstrument = InstrAlloc(n);
		else
			resultRelInfo->ri_TrigInstrument = NULL;
	}
	else
	{
		resultRelInfo->ri_TrigFunctions = NULL;
		resultRelInfo->ri_TrigInstrument = NULL;
	}
	resultRelInfo->ri_ConstraintExprs = NULL;
	resultRelInfo->ri_junkFilter = NULL;

	/*
	 * If there are indices on the result relation, open them and save
	 * descriptors in the result relation info, so that we can add new index
	 * entries for the tuples we add/update.  We need not do this for a
	 * DELETE, however, since deletion doesn't affect indexes.
	 */
	if (resultRelationDesc->rd_rel->relhasindex &&
		operation != CMD_DELETE)
		ExecOpenIndices(resultRelInfo);
}

/*
 *		ExecContextForcesOids
 *
 * This is pretty grotty: when doing INSERT, UPDATE, or SELECT INTO,
 * we need to ensure that result tuples have space for an OID iff they are
 * going to be stored into a relation that has OIDs.  In other contexts
 * we are free to choose whether to leave space for OIDs in result tuples
 * (we generally don't want to, but we do if a physical-tlist optimization
 * is possible).  This routine checks the plan context and returns TRUE if the
 * choice is forced, FALSE if the choice is not forced.  In the TRUE case,
 * *hasoids is set to the required value.
 *
 * One reason this is ugly is that all plan nodes in the plan tree will emit
 * tuples with space for an OID, though we really only need the topmost node
 * to do so.  However, node types like Sort don't project new tuples but just
 * return their inputs, and in those cases the requirement propagates down
 * to the input node.  Eventually we might make this code smart enough to
 * recognize how far down the requirement really goes, but for now we just
 * make all plan nodes do the same thing if the top level forces the choice.