execmain.c

PostgreSQL7.4.6 for Linux

			while (resultRelations != NIL)
			{
				initResultRelInfo(resultRelInfo,
								  lfirsti(resultRelations),
								  rangeTable,
								  operation);
				resultRelInfo++;
				resultRelations = lnext(resultRelations);
			}
		}
		else
		{
			/*
			 * Single result relation identified by
			 * parseTree->resultRelation
			 */
			numResultRelations = 1;
			resultRelInfos = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
			initResultRelInfo(resultRelInfos,
							  parseTree->resultRelation,
							  rangeTable,
							  operation);
		}

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

	/*
	 * Detect whether we're doing SELECT INTO.  If so, set the force_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;

		/*
		 * For now, always create OIDs in SELECT INTO; this is for
		 * backwards compatibility with pre-7.3 behavior.  Eventually we
		 * might want to allow the user to choose.
		 */
		estate->es_into_oids = true;
	}

	/*
	 * Have to lock relations selected for update
	 */
	estate->es_rowMark = NIL;
	if (parseTree->rowMarks != NIL)
	{
		List	   *l;

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

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

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

		if (parseTree->resultRelations != NIL)
			nSlots += length(parseTree->resultRelations);
		else
			nSlots += 1;
		estate->es_tupleTable = ExecCreateTupleTable(nSlots);
	}

	/* mark EvalPlanQual not active */
	estate->es_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;
		List	   *tlist;

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

					if (tle->resdom->resjunk)
					{
						junk_filter_needed = true;
						break;
					}
				}
				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,
										   ExecGetResultType(subplan),
							  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,
							  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 = (Relation) NULL;

	if (do_select_into && !explainOnly)
	{
		char	   *intoName;
		Oid			namespaceId;
		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));

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

		intoRelationId = heap_create_with_catalog(intoName,
												  namespaceId,
												  tupdesc,
												  RELKIND_RELATION,
												  false,
												  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);
	}

	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)
{
	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);
	resultRelInfo->ri_TrigFunctions = NULL;
	resultRelInfo->ri_ConstraintExprs = NULL;
	resultRelInfo->ri_junkFilter = NULL;

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

/*
 *		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.
 *
 * We assume that estate->es_result_relation_info is already set up to
 * describe the target relation.  Note that in an UPDATE that spans an
 * inheritance tree, some of the target relations may have OIDs and some not.
 * We have to make the decisions on a per-relation basis as we initialize
 * each of the child plans of the topmost Append plan.
 *
 * SELECT INTO is even uglier, because we don't have the INTO relation's
 * descriptor available when this code runs; we have to look aside at a
 * flag set by InitPlan().
 */
bool
ExecContextForcesOids(PlanState *planstate, bool *hasoids)
{
	if (planstate->state->es_select_into)
	{
		*hasoids = planstate->state->es_into_oids;
		return true;
	}
	else
	{
		ResultRelInfo *ri = planstate->state->es_result_relation_info;

		if (ri != NULL)
		{
			Relation	rel = ri->ri_RelationDesc;

			if (rel != NULL)
			{
				*hasoids = rel->rd_rel->relhasoids;
				return true;
			}
		}
	}

	return false;
}

/* ----------------------------------------------------------------
 *		ExecEndPlan
 *
 *		Cleans up the query plan -- closes files and frees up storage
 *
 * NOTE: we are no longer very worried about freeing storage per se
 * in this code; FreeExecutorState should be guaranteed to release all
 * memory that needs to be released.  What we are worried about doing
 * is closing relations and dropping buffer pins.  Thus, for example,
 * tuple tables must be cleared or dropped to ensure pins are released.
 * ----------------------------------------------------------------
 */
void
ExecEndPlan(PlanState *planstate, EState *estate)
{
	ResultRelInfo *resultRelInfo;
	int			i;
	List	   *l;

	/*
	 * shut down any PlanQual processing we were doing
	 */
	if (estate->es_evalPlanQual != NULL)
		EndEvalPlanQual(estate);

	/*
	 * shut down the node-type-specific query processing
	 */
	ExecEndNode(planstate);

	/*
	 * destroy the executor "tuple" table.
	 */
	ExecDropTupleTable(estate->es_tupleTable, true);
	estate->es_tupleTable = NULL;

	/*
	 * close the result relation(s) if any, but hold locks until xact
	 * commit.
	 */
	resultRelInfo = estate->es_result_relations;
	for (i = estate->es_num_result_relations; i > 0; i--)
	{
		/* Close indices and then the relation itself */
		ExecCloseIndices(resultRelInfo);
		heap_close(resultRelInfo->ri_RelationDesc, NoLock);
		resultRelInfo++;
	}

	/*
	 * close the "into" relation if necessary, again keeping lock
	 */
	if (estate->es_into_relation_descriptor != NULL)
		heap_close(estate->es_into_relation_descriptor, NoLock);

	/*
	 * close any relations selected FOR UPDATE, again keeping locks
	 */
	foreach(l, estate->es_rowMark)
	{
		execRowMark *erm = lfirst(l);

		heap_close(erm->relation, NoLock);
	}
}

/* ----------------------------------------------------------------
 *		ExecutePlan
 *
 *		processes the query plan to retrieve 'numberTuples' tuples in the
 *		direction specified.
 *
 *		Retrieves all tuples if numberTuples is 0
 *
 *		result is either a slot containing the last tuple in the case
 *		of a SELECT or NULL otherwise.
 *
 * Note: the ctid attribute is a 'junk' attribute that is removed before the
 * user can see it
 * ----------------------------------------------------------------
 */
static TupleTableSlot *
ExecutePlan(EState *estate,
			PlanState *planstate,
			CmdType operation,
			long numberTuples,
			ScanDirection direction,
			DestReceiver *dest)
{
	JunkFilter *junkfilter;
	TupleTableSlot *slot;
	ItemPointer tupleid = NULL;
	ItemPointerData tuple_ctid;
	long		current_tuple_count;
	TupleTableSlot *result;

	/*
	 * initialize local variables
	 */
	slot = NULL;
	current_tuple_count = 0;
	result = NULL;

	/*
	 * Set the direction.
	 */
	estate->es_direction = direction;

	/*
	 * Process BEFORE EACH STATEMENT triggers
	 */
	switch (operation)
	{
		case CMD_UPDATE:
			ExecBSUpdateTriggers(estate, estate->es_result_relation_info);
			break;
		case CMD_DELETE:
			ExecBSDeleteTriggers(estate, estate->es_result_relation_info);
			break;
		case CMD_INSERT:
			ExecBSInsertTriggers(estate, estate->es_result_relation_info);
			break;
		default:
			/* do nothing */
			break;
	}

	/*
	 * Loop until we've processed the proper number of tuples from the
	 * plan.
	 */

	for (;;)
	{