index.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	ii->ii_ExpressionsState = NIL;

	/* fetch index predicate if any */
	ii->ii_Predicate = RelationGetIndexPredicate(index);
	ii->ii_PredicateState = NIL;

	/* other info */
	ii->ii_Unique = indexStruct->indisunique;

	return ii;
}

/* ----------------
 *		FormIndexDatum
 *			Construct values[] and isnull[] arrays for a new index tuple.
 *
 *	indexInfo		Info about the index
 *	slot			Heap tuple for which we must prepare an index entry
 *	estate			executor state for evaluating any index expressions
 *	values			Array of index Datums (output area)
 *	isnull			Array of is-null indicators (output area)
 *
 * When there are no index expressions, estate may be NULL.  Otherwise it
 * must be supplied, *and* the ecxt_scantuple slot of its per-tuple expr
 * context must point to the heap tuple passed in.
 *
 * Notice we don't actually call index_form_tuple() here; we just prepare
 * its input arrays values[] and isnull[].	This is because the index AM
 * may wish to alter the data before storage.
 * ----------------
 */
void
FormIndexDatum(IndexInfo *indexInfo,
			   TupleTableSlot *slot,
			   EState *estate,
			   Datum *values,
			   bool *isnull)
{
	ListCell   *indexpr_item;
	int			i;

	if (indexInfo->ii_Expressions != NIL &&
		indexInfo->ii_ExpressionsState == NIL)
	{
		/* First time through, set up expression evaluation state */
		indexInfo->ii_ExpressionsState = (List *)
			ExecPrepareExpr((Expr *) indexInfo->ii_Expressions,
							estate);
		/* Check caller has set up context correctly */
		Assert(GetPerTupleExprContext(estate)->ecxt_scantuple == slot);
	}
	indexpr_item = list_head(indexInfo->ii_ExpressionsState);

	for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
	{
		int			keycol = indexInfo->ii_KeyAttrNumbers[i];
		Datum		iDatum;
		bool		isNull;

		if (keycol != 0)
		{
			/*
			 * Plain index column; get the value we need directly from the
			 * heap tuple.
			 */
			iDatum = slot_getattr(slot, keycol, &isNull);
		}
		else
		{
			/*
			 * Index expression --- need to evaluate it.
			 */
			if (indexpr_item == NULL)
				elog(ERROR, "wrong number of index expressions");
			iDatum = ExecEvalExprSwitchContext((ExprState *) lfirst(indexpr_item),
											   GetPerTupleExprContext(estate),
											   &isNull,
											   NULL);
			indexpr_item = lnext(indexpr_item);
		}
		values[i] = iDatum;
		isnull[i] = isNull;
	}

	if (indexpr_item != NULL)
		elog(ERROR, "wrong number of index expressions");
}


/* ----------------
 *		set relhasindex of relation's pg_class entry
 *
 * If isprimary is TRUE, we are defining a primary index, so also set
 * relhaspkey to TRUE.	Otherwise, leave relhaspkey alone.
 *
 * If reltoastidxid is not InvalidOid, also set reltoastidxid to that value.
 * This is only used for TOAST relations.
 *
 * NOTE: an important side-effect of this operation is that an SI invalidation
 * message is sent out to all backends --- including me --- causing relcache
 * entries to be flushed or updated with the new hasindex data.  This must
 * happen even if we find that no change is needed in the pg_class row.
 * ----------------
 */
void
setRelhasindex(Oid relid, bool hasindex, bool isprimary, Oid reltoastidxid)
{
	Relation	pg_class;
	HeapTuple	tuple;
	Form_pg_class classtuple;
	bool		dirty = false;
	HeapScanDesc pg_class_scan = NULL;

	/*
	 * Find the tuple to update in pg_class.  In bootstrap mode we can't use
	 * heap_update, so cheat and overwrite the tuple in-place.	In normal
	 * processing, make a copy to scribble on.
	 */
	pg_class = heap_open(RelationRelationId, RowExclusiveLock);

	if (!IsBootstrapProcessingMode())
	{
		tuple = SearchSysCacheCopy(RELOID,
								   ObjectIdGetDatum(relid),
								   0, 0, 0);
	}
	else
	{
		ScanKeyData key[1];

		ScanKeyInit(&key[0],
					ObjectIdAttributeNumber,
					BTEqualStrategyNumber, F_OIDEQ,
					ObjectIdGetDatum(relid));

		pg_class_scan = heap_beginscan(pg_class, SnapshotNow, 1, key);
		tuple = heap_getnext(pg_class_scan, ForwardScanDirection);
	}

	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "could not find tuple for relation %u", relid);
	classtuple = (Form_pg_class) GETSTRUCT(tuple);

	/* Apply required updates */

	if (pg_class_scan)
		LockBuffer(pg_class_scan->rs_cbuf, BUFFER_LOCK_EXCLUSIVE);

	if (classtuple->relhasindex != hasindex)
	{
		classtuple->relhasindex = hasindex;
		dirty = true;
	}
	if (isprimary)
	{
		if (!classtuple->relhaspkey)
		{
			classtuple->relhaspkey = true;
			dirty = true;
		}
	}
	if (OidIsValid(reltoastidxid))
	{
		Assert(classtuple->relkind == RELKIND_TOASTVALUE);
		if (classtuple->reltoastidxid != reltoastidxid)
		{
			classtuple->reltoastidxid = reltoastidxid;
			dirty = true;
		}
	}

	if (pg_class_scan)
		LockBuffer(pg_class_scan->rs_cbuf, BUFFER_LOCK_UNLOCK);

	if (pg_class_scan)
	{
		/* Write the modified tuple in-place */
		WriteNoReleaseBuffer(pg_class_scan->rs_cbuf);
		/* Send out shared cache inval if necessary */
		if (!IsBootstrapProcessingMode())
			CacheInvalidateHeapTuple(pg_class, tuple);
	}
	else if (dirty)
	{
		simple_heap_update(pg_class, &tuple->t_self, tuple);

		/* Keep the catalog indexes up to date */
		CatalogUpdateIndexes(pg_class, tuple);
	}
	else
	{
		/* no need to change tuple, but force relcache rebuild anyway */
		CacheInvalidateRelcacheByTuple(tuple);
	}

	if (!pg_class_scan)
		heap_freetuple(tuple);
	else
		heap_endscan(pg_class_scan);

	heap_close(pg_class, RowExclusiveLock);
}

/*
 * setNewRelfilenode		- assign a new relfilenode value to the relation
 *
 * Caller must already hold exclusive lock on the relation.
 */
void
setNewRelfilenode(Relation relation)
{
	Oid			newrelfilenode;
	RelFileNode newrnode;
	SMgrRelation srel;
	Relation	pg_class;
	HeapTuple	tuple;
	Form_pg_class rd_rel;

	/* Can't change relfilenode for nailed tables (indexes ok though) */
	Assert(!relation->rd_isnailed ||
		   relation->rd_rel->relkind == RELKIND_INDEX);
	/* Can't change for shared tables or indexes */
	Assert(!relation->rd_rel->relisshared);

	/* Allocate a new relfilenode */
	newrelfilenode = GetNewRelFileNode(relation->rd_rel->reltablespace,
									   relation->rd_rel->relisshared,
									   NULL);

	/*
	 * Find the pg_class tuple for the given relation.	This is not used
	 * during bootstrap, so okay to use heap_update always.
	 */
	pg_class = heap_open(RelationRelationId, RowExclusiveLock);

	tuple = SearchSysCacheCopy(RELOID,
							   ObjectIdGetDatum(RelationGetRelid(relation)),
							   0, 0, 0);
	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "could not find tuple for relation %u",
			 RelationGetRelid(relation));
	rd_rel = (Form_pg_class) GETSTRUCT(tuple);

	/* create another storage file. Is it a little ugly ? */
	/* NOTE: any conflict in relfilenode value will be caught here */
	newrnode = relation->rd_node;
	newrnode.relNode = newrelfilenode;

	srel = smgropen(newrnode);
	smgrcreate(srel, relation->rd_istemp, false);
	smgrclose(srel);

	/* schedule unlinking old relfilenode */
	RelationOpenSmgr(relation);
	smgrscheduleunlink(relation->rd_smgr, relation->rd_istemp);

	/* update the pg_class row */
	rd_rel->relfilenode = newrelfilenode;
	rd_rel->relpages = 0;		/* it's empty until further notice */
	rd_rel->reltuples = 0;
	simple_heap_update(pg_class, &tuple->t_self, tuple);
	CatalogUpdateIndexes(pg_class, tuple);

	heap_freetuple(tuple);

	heap_close(pg_class, RowExclusiveLock);

	/* Make sure the relfilenode change is visible */
	CommandCounterIncrement();
}


/*
 * This is invoked by the various index AMs once they have finished
 * constructing an index. Constructing an index involves counting the
 * number of tuples in both the relation and the index, so we take
 * advantage of the opportunity to update pg_class to ensure that the
 * planner takes advantage of the index we just created.  But, only
 * update statistics during normal index definitions, not for indices
 * on system catalogs created during bootstrap processing.	We must
 * close the relations before updating statistics to guarantee that
 * the relcache entries are flushed when we increment the command
 * counter in UpdateStats(). But we do not release any locks on the
 * relations; those will be held until end of transaction.
 */
void
IndexCloseAndUpdateStats(Relation heap, double heapTuples,
						 Relation index, double indexTuples)
{
	Oid			hrelid = RelationGetRelid(heap);
	Oid			irelid = RelationGetRelid(index);

	if (!IsNormalProcessingMode())
		return;

	heap_close(heap, NoLock);
	index_close(index);
	UpdateStats(hrelid, heapTuples);
	UpdateStats(irelid, indexTuples);
}


/* ----------------
 *		UpdateStats
 *
 * Update pg_class' relpages and reltuples statistics for the given relation
 * (which can be either a table or an index).  Note that this is not used
 * in the context of VACUUM, only CREATE INDEX.
 * ----------------
 */
static void
UpdateStats(Oid relid, double reltuples)
{
	Relation	whichRel;
	Relation	pg_class;
	HeapTuple	tuple;
	BlockNumber relpages;
	Form_pg_class rd_rel;
	HeapScanDesc pg_class_scan = NULL;
	bool		in_place_upd;

	/*
	 * This routine handles updates for both the heap and index relation
	 * statistics.	In order to guarantee that we're able to *see* the index
	 * relation tuple, we bump the command counter id here.  The index
	 * relation tuple was created in the current transaction.
	 */
	CommandCounterIncrement();

	/*
	 * CommandCounterIncrement() flushes invalid cache entries, including
	 * those for the heap and index relations for which we're updating
	 * statistics.	Now that the cache is flushed, it's safe to open the
	 * relation again.	We need the relation open in order to figure out how
	 * many blocks it contains.
	 */

	/*
	 * Grabbing lock here is probably redundant ...
	 */
	whichRel = relation_open(relid, ShareLock);

	/*
	 * Find the tuple to update in pg_class.  Normally we make a copy of the
	 * tuple using the syscache, modify it, and apply heap_update. But in
	 * bootstrap mode we can't use heap_update, so we cheat and overwrite the
	 * tuple in-place.	(Note: as of PG 8.0 this isn't called during
	 * bootstrap, but leave the code here for possible future use.)
	 *
	 * We also must cheat if reindexing pg_class itself, because the target
	 * index may presently not be part of the set of indexes that
	 * CatalogUpdateIndexes would update (see reindex_relation).  In this case
	 * the stats updates will not be WAL-logged and so could be lost in a
	 * crash.  This seems OK considering VACUUM does the same thing.
	 */
	pg_class = heap_open(RelationRelationId, RowExclusiveLock);

	in_place_upd = IsBootstrapProcessingMode() ||
		ReindexIsProcessingHeap(RelationRelationId);

	if (!in_place_upd)
	{
		tuple = SearchSysCacheCopy(RELOID,
								   ObjectIdGetDatum(relid),
								   0, 0, 0);
	}
	else
	{
		ScanKeyData key[1];

		ScanKeyInit(&key[0],
					ObjectIdAttributeNumber,
					BTEqualStrategyNumber, F_OIDEQ,
					ObjectIdGetDatum(relid));

		pg_class_scan = heap_beginscan(pg_class, SnapshotNow, 1, key);
		tuple = heap_getnext(pg_class_scan, ForwardScanDirection);
	}

	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "could not find tuple for relation %u", relid);
	rd_rel = (Form_pg_class) GETSTRUCT(tuple);

	/*
	 * Update statistics in pg_class, if they changed.	(Avoiding an
	 * unnecessary update is not just a tiny performance improvement; it also
	 * reduces the window wherein concurrent CREATE INDEX commands may
	 * conflict.)
	 */
	relpages = RelationGetNumberOfBlocks(whichRel);

	if (rd_rel->relpages != (int32) relpages ||
		rd_rel->reltuples != (float4) reltuples)
	{
		if (in_place_upd)
		{
			/* Bootstrap or reindex case: overwrite fields in place. */
			LockBuffer(pg_class_scan->rs_cbuf, BUFFER_LOCK_EXCLUSIVE);
			rd_rel->relpages = (int32) relpages;
			rd_rel->reltuples = (float4) reltuples;
			LockBuffer(pg_class_scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
			WriteNoReleaseBuffer(pg_class_scan->rs_cbuf);
			if (!IsBootstrapProcessingMode())
				CacheInvalidateHeapTuple(pg_class, tuple);
		}
		else
		{
			/* During normal processing, must work harder. */
			rd_rel->relpages = (int32) relpages;
			rd_rel->reltuples = (float4) reltuples;
			simple_heap_update(pg_class, &tuple->t_self, tuple);
			CatalogUpdateIndexes(pg_class, tuple);
		}
	}

	if (in_place_upd)
		heap_endscan(pg_class_scan);
	else
		heap_freetuple(tuple);

	/*
	 * We shouldn't have to do this, but we do...  Modify the reldesc in place
	 * with the new values so that the cache contains the latest copy.	(XXX
	 * is this really still necessary?	The relcache will get fixed at next
	 * CommandCounterIncrement, so why bother here?)
	 */
	whichRel->rd_rel->relpages = (int32) relpages;
	whichRel->rd_rel->reltuples = (float4) reltuples;

	heap_close(pg_class, RowExclusiveLock);
	relation_close(whichRel, NoLock);
}


/*
 * index_build - invoke access-method-specific index build procedure
 */
void
index_build(Relation heapRelation,
			Relation indexRelation,
			IndexInfo *indexInfo)
{
	RegProcedure procedure;

	/*
	 * sanity checks
	 */
	Assert(RelationIsValid(indexRelation));