executils.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

		int		   *varNumbers;
		AttrNumber	lastInnerVar = 0;
		AttrNumber	lastOuterVar = 0;
		AttrNumber	lastScanVar = 0;

		projInfo->pi_itemIsDone = NULL; /* not needed */
		projInfo->pi_varSlotOffsets = varSlotOffsets = (int *)
			palloc0(len * sizeof(int));
		projInfo->pi_varNumbers = varNumbers = (int *)
			palloc0(len * sizeof(int));

		/*
		 * Set up the data needed by ExecVariableList.	The slots in which the
		 * variables can be found at runtime are denoted by the offsets of
		 * their slot pointers within the econtext.  This rather grotty
		 * representation is needed because the caller may not have given us
		 * the real econtext yet (see hacks in nodeSubplan.c).
		 */
		foreach(tl, targetList)
		{
			GenericExprState *gstate = (GenericExprState *) lfirst(tl);
			Var		   *variable = (Var *) gstate->arg->expr;
			AttrNumber	attnum = variable->varattno;
			TargetEntry *tle = (TargetEntry *) gstate->xprstate.expr;
			AttrNumber	resind = tle->resno - 1;

			Assert(resind >= 0 && resind < len);
			varNumbers[resind] = attnum;

			switch (variable->varno)
			{
				case INNER:
					varSlotOffsets[resind] = offsetof(ExprContext,
													  ecxt_innertuple);
					lastInnerVar = Max(lastInnerVar, attnum);
					break;

				case OUTER:
					varSlotOffsets[resind] = offsetof(ExprContext,
													  ecxt_outertuple);
					lastOuterVar = Max(lastOuterVar, attnum);
					break;

				default:
					varSlotOffsets[resind] = offsetof(ExprContext,
													  ecxt_scantuple);
					lastScanVar = Max(lastScanVar, attnum);
					break;
			}
		}
		projInfo->pi_lastInnerVar = lastInnerVar;
		projInfo->pi_lastOuterVar = lastOuterVar;
		projInfo->pi_lastScanVar = lastScanVar;
	}
	else
	{
		projInfo->pi_itemIsDone = (ExprDoneCond *)
			palloc(len * sizeof(ExprDoneCond));
		projInfo->pi_varSlotOffsets = NULL;
		projInfo->pi_varNumbers = NULL;
	}

	return projInfo;
}

/* ----------------
 *		ExecAssignProjectionInfo
 *
 * forms the projection information from the node's targetlist
 * ----------------
 */
void
ExecAssignProjectionInfo(PlanState *planstate)
{
	planstate->ps_ProjInfo =
		ExecBuildProjectionInfo(planstate->targetlist,
								planstate->ps_ExprContext,
								planstate->ps_ResultTupleSlot);
}


/* ----------------
 *		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, bool shouldFree)
{
	TupleTableSlot *slot = scanstate->ss_ScanTupleSlot;

	ExecSetSlotDescriptor(slot, tupDesc, shouldFree);
}

/* ----------------
 *		ExecAssignScanTypeFromOuterPlan
 * ----------------
 */
void
ExecAssignScanTypeFromOuterPlan(ScanState *scanstate)
{
	PlanState  *outerPlan;
	TupleDesc	tupDesc;

	outerPlan = outerPlanState(scanstate);
	tupDesc = ExecGetResultType(outerPlan);

	ExecAssignScanType(scanstate, tupDesc, false);
}


/* ----------------------------------------------------------------
 *				  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.
 *
 *		This used to be horribly ugly code, and slow too because it
 *		did a sequential scan of pg_index.	Now we rely on the relcache
 *		to cache a list of the OIDs of the indices associated with any
 *		specific relation, and we use the pg_index syscache to get the
 *		entries we need from pg_index.
 * ----------------------------------------------------------------
 */
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.
	 */
	i = 0;
	foreach(l, indexoidlist)
	{
		Oid			indexOid = lfirst_oid(l);
		Relation	indexDesc;
		IndexInfo  *ii;

		/*
		 * Open and lock the index relation
		 *
		 * If the index AM supports concurrent updates, obtain
		 * RowExclusiveLock to signify that we are updating the index.	This
		 * locks out only operations that need exclusive access, such as
		 * relocating the index to a new tablespace.
		 *
		 * If the index AM is not safe for concurrent updates, obtain an
		 * exclusive lock on the index to lock out other updaters as well as
		 * readers (index_beginscan places AccessShareLock).
		 *
		 * If there are multiple not-concurrent-safe indexes, all backends
		 * must lock the indexes in the same order or we will get deadlocks
		 * here. This is guaranteed by RelationGetIndexList(), which promises
		 * to return the index list in OID order.
		 *
		 * The locks will be released in ExecCloseIndices.
		 */
		indexDesc = index_open(indexOid);

		if (indexDesc->rd_am->amconcurrent)
			LockRelation(indexDesc, RowExclusiveLock);
		else
			LockRelation(indexDesc, AccessExclusiveLock);

		/* 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 */
		if (indexDescs[i]->rd_am->amconcurrent)
			UnlockRelation(indexDescs[i], RowExclusiveLock);
		else
			UnlockRelation(indexDescs[i], AccessExclusiveLock);

		index_close(indexDescs[i]);
	}

	/*
	 * 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
 * ----------------------------------------------------------------
 */
void
ExecInsertIndexTuples(TupleTableSlot *slot,
					  ItemPointer tupleid,
					  EState *estate,
					  bool is_vacuum)
{
	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++)
	{
		IndexInfo  *indexInfo;

		if (relationDescs[i] == NULL)
			continue;

		indexInfo = indexInfoArray[i];

		/* 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 rest.	Note we suppress unique-index checks
		 * if we are being called from VACUUM, since VACUUM may need to move
		 * dead tuples that have the same keys as live ones.
		 */
		index_insert(relationDescs[i],	/* index relation */
					 values,	/* array of index Datums */
					 isnull,	/* null flags */
					 tupleid,	/* tid of heap tuple */
					 heapRelation,
					 relationDescs[i]->rd_index->indisunique && !is_vacuum);

		/*
		 * keep track of index inserts for debugging
		 */
		IncrIndexInserted();
	}
}

/*
 * 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).
 */
static void
ShutdownExprContext(ExprContext *econtext)
{
	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;
		(*ecxt_callback->function) (ecxt_callback->arg);
		pfree(ecxt_callback);
	}

	MemoryContextSwitchTo(oldcontext);
}