Clean up code associated with updating pg_class statistics columns

(relpages/reltuples).  To do this, create formal support in heapam.c for
"overwrite" tuple updates (including xlog replay capability) and use that
instead of the ad-hoc overwrites we'd been using in VACUUM and CREATE INDEX.
Take the responsibility for updating stats during CREATE INDEX out of the
individual index AMs, and do it where it belongs, in catalog/index.c.  Aside
from being more modular, this avoids having to update the same tuple twice in
some paths through CREATE INDEX.  It's probably not measurably faster, but
for sure it's a lot cleaner than before.

doc/src/sgml/indexam.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.10 2006/05/02 22:25:09 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.11 2006/05/10 23:18:38 tgl Exp $ -->
 
 <chapter id="indexam">
  <title>Index Access Method Interface Definition</title>
@@ -144,7 +144,7 @@
 
   <para>
 <programlisting>
-void
+IndexBuildResult *
 ambuild (Relation heapRelation,
          Relation indexRelation,
          IndexInfo *indexInfo);
@@ -155,6 +155,8 @@ ambuild (Relation heapRelation,
    in the table.  Ordinarily the <function>ambuild</> function will call
    <function>IndexBuildHeapScan()</> to scan the table for existing tuples
    and compute the keys that need to be inserted into the index.
+   The function must return a palloc'd struct containing statistics about
+   the new index.
   </para>
 
   <para>

src/backend/access/gin/gininsert.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *          $PostgreSQL: pgsql/src/backend/access/gin/gininsert.c,v 1.1 2006/05/02 11:28:54 teodor Exp $
+ *          $PostgreSQL: pgsql/src/backend/access/gin/gininsert.c,v 1.2 2006/05/10 23:18:38 tgl Exp $
  *-------------------------------------------------------------------------
  */
 
@@ -242,6 +242,7 @@ ginbuild(PG_FUNCTION_ARGS) {
 	Relation    heap = (Relation) PG_GETARG_POINTER(0);
 	Relation    index = (Relation) PG_GETARG_POINTER(1);
 	IndexInfo  *indexInfo = (IndexInfo *) PG_GETARG_POINTER(2);
+	IndexBuildResult *result;
 	double      reltuples;
 	GinBuildState	buildstate;
 	Buffer		buffer;
@@ -310,10 +311,15 @@ ginbuild(PG_FUNCTION_ARGS) {
 
 	MemoryContextDelete(buildstate.tmpCtx);
 
-	/* since we just counted the # of tuples, may as well update stats */
-	IndexCloseAndUpdateStats(heap, reltuples, index, buildstate.indtuples);
+	/*
+	 * Return statistics
+	 */
+	result = (IndexBuildResult *) palloc(sizeof(IndexBuildResult));
+
+	result->heap_tuples = reltuples;
+	result->index_tuples = buildstate.indtuples;
 
-	PG_RETURN_VOID();
+	PG_RETURN_POINTER(result);
 }
 
 /*

src/backend/access/gist/gist.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/gist/gist.c,v 1.133 2006/05/10 09:19:54 teodor Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/gist/gist.c,v 1.134 2006/05/10 23:18:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -89,6 +89,7 @@ gistbuild(PG_FUNCTION_ARGS)
 	Relation	heap = (Relation) PG_GETARG_POINTER(0);
 	Relation	index = (Relation) PG_GETARG_POINTER(1);
 	IndexInfo  *indexInfo = (IndexInfo *) PG_GETARG_POINTER(2);
+	IndexBuildResult *result;
 	double		reltuples;
 	GISTBuildState buildstate;
 	Buffer		buffer;
@@ -154,12 +155,17 @@ gistbuild(PG_FUNCTION_ARGS)
 	/* okay, all heap tuples are indexed */
 	MemoryContextDelete(buildstate.tmpCtx);
 
-	/* since we just counted the # of tuples, may as well update stats */
-	IndexCloseAndUpdateStats(heap, reltuples, index, buildstate.indtuples);
-
 	freeGISTstate(&buildstate.giststate);
 
-	PG_RETURN_VOID();
+	/*
+	 * Return statistics
+	 */
+	result = (IndexBuildResult *) palloc(sizeof(IndexBuildResult));
+
+	result->heap_tuples = reltuples;
+	result->index_tuples = buildstate.indtuples;
+
+	PG_RETURN_POINTER(result);
 }
 
 /*

src/backend/access/hash/hash.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/hash/hash.c,v 1.89 2006/05/02 22:25:10 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/hash/hash.c,v 1.90 2006/05/10 23:18:38 tgl Exp $
  *
  * NOTES
  *	  This file contains only the public interface routines.
@@ -51,6 +51,7 @@ hashbuild(PG_FUNCTION_ARGS)
 	Relation	heap = (Relation) PG_GETARG_POINTER(0);
 	Relation	index = (Relation) PG_GETARG_POINTER(1);
 	IndexInfo  *indexInfo = (IndexInfo *) PG_GETARG_POINTER(2);
+	IndexBuildResult *result;
 	double		reltuples;
 	HashBuildState buildstate;
 
@@ -72,10 +73,15 @@ hashbuild(PG_FUNCTION_ARGS)
 	reltuples = IndexBuildHeapScan(heap, index, indexInfo,
 								   hashbuildCallback, (void *) &buildstate);
 
-	/* since we just counted the # of tuples, may as well update stats */
-	IndexCloseAndUpdateStats(heap, reltuples, index, buildstate.indtuples);
+	/*
+	 * Return statistics
+	 */
+	result = (IndexBuildResult *) palloc(sizeof(IndexBuildResult));
 
-	PG_RETURN_VOID();
+	result->heap_tuples = reltuples;
+	result->index_tuples = buildstate.indtuples;
+
+	PG_RETURN_POINTER(result);
 }
 
 /*

src/backend/access/heap/heapam.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.211 2006/03/31 23:32:05 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.212 2006/05/10 23:18:39 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -2673,6 +2673,97 @@ l3:
 	return HeapTupleMayBeUpdated;
 }
 
+
+/*
+ * heap_inplace_update - update a tuple "in place" (ie, overwrite it)
+ *
+ * Overwriting violates both MVCC and transactional safety, so the uses
+ * of this function in Postgres are extremely limited.  Nonetheless we
+ * find some places to use it.
+ *
+ * The tuple cannot change size, and therefore it's reasonable to assume
+ * that its null bitmap (if any) doesn't change either.  So we just
+ * overwrite the data portion of the tuple without touching the null
+ * bitmap or any of the header fields.
+ *
+ * tuple is an in-memory tuple structure containing the data to be written
+ * over the target tuple.  Also, tuple->t_self identifies the target tuple.
+ */
+void
+heap_inplace_update(Relation relation, HeapTuple tuple)
+{
+	Buffer		buffer;
+	Page		page;
+	OffsetNumber offnum;
+	ItemId		lp = NULL;
+	HeapTupleHeader htup;
+	uint32		oldlen;
+	uint32		newlen;
+
+	buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&(tuple->t_self)));
+	LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
+	page = (Page) BufferGetPage(buffer);
+
+	offnum = ItemPointerGetOffsetNumber(&(tuple->t_self));
+	if (PageGetMaxOffsetNumber(page) >= offnum)
+		lp = PageGetItemId(page, offnum);
+
+	if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsUsed(lp))
+		elog(ERROR, "heap_inplace_update: invalid lp");
+
+	htup = (HeapTupleHeader) PageGetItem(page, lp);
+
+	oldlen = ItemIdGetLength(lp) - htup->t_hoff;
+	newlen = tuple->t_len - tuple->t_data->t_hoff;
+	if (oldlen != newlen || htup->t_hoff != tuple->t_data->t_hoff)
+		elog(ERROR, "heap_inplace_update: wrong tuple length");
+
+	/* NO EREPORT(ERROR) from here till changes are logged */
+	START_CRIT_SECTION();
+
+	memcpy((char *) htup + htup->t_hoff,
+		   (char *) tuple->t_data + tuple->t_data->t_hoff,
+		   newlen);
+
+	MarkBufferDirty(buffer);
+
+	/* XLOG stuff */
+	if (!relation->rd_istemp)
+	{
+		xl_heap_inplace xlrec;
+		XLogRecPtr	recptr;
+		XLogRecData rdata[2];
+
+		xlrec.target.node = relation->rd_node;
+		xlrec.target.tid = tuple->t_self;
+
+		rdata[0].data = (char *) &xlrec;
+		rdata[0].len = SizeOfHeapInplace;
+		rdata[0].buffer = InvalidBuffer;
+		rdata[0].next = &(rdata[1]);
+
+		rdata[1].data = (char *) htup + htup->t_hoff;
+		rdata[1].len = newlen;
+		rdata[1].buffer = buffer;
+		rdata[1].buffer_std = true;
+		rdata[1].next = NULL;
+
+		recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_INPLACE, rdata);
+
+		PageSetLSN(page, recptr);
+		PageSetTLI(page, ThisTimeLineID);
+	}
+
+	END_CRIT_SECTION();
+
+	UnlockReleaseBuffer(buffer);
+
+	/* Send out shared cache inval if necessary */
+	if (!IsBootstrapProcessingMode())
+		CacheInvalidateHeapTuple(relation, tuple);
+}
+
+
 /* ----------------
  *		heap_markpos	- mark scan position
  * ----------------
@@ -3329,6 +3420,59 @@ heap_xlog_lock(XLogRecPtr lsn, XLogRecord *record)
 	UnlockReleaseBuffer(buffer);
 }
 
+static void
+heap_xlog_inplace(XLogRecPtr lsn, XLogRecord *record)
+{
+	xl_heap_inplace *xlrec = (xl_heap_inplace *) XLogRecGetData(record);
+	Relation	reln = XLogOpenRelation(xlrec->target.node);
+	Buffer		buffer;
+	Page		page;
+	OffsetNumber offnum;
+	ItemId		lp = NULL;
+	HeapTupleHeader htup;
+	uint32		oldlen;
+	uint32		newlen;
+
+	if (record->xl_info & XLR_BKP_BLOCK_1)
+		return;
+
+	buffer = XLogReadBuffer(reln,
+							ItemPointerGetBlockNumber(&(xlrec->target.tid)),
+							false);
+	if (!BufferIsValid(buffer))
+		return;
+	page = (Page) BufferGetPage(buffer);
+
+	if (XLByteLE(lsn, PageGetLSN(page)))		/* changes are applied */
+	{
+		UnlockReleaseBuffer(buffer);
+		return;
+	}
+
+	offnum = ItemPointerGetOffsetNumber(&(xlrec->target.tid));
+	if (PageGetMaxOffsetNumber(page) >= offnum)
+		lp = PageGetItemId(page, offnum);
+
+	if (PageGetMaxOffsetNumber(page) < offnum || !ItemIdIsUsed(lp))
+		elog(PANIC, "heap_inplace_redo: invalid lp");
+
+	htup = (HeapTupleHeader) PageGetItem(page, lp);
+
+	oldlen = ItemIdGetLength(lp) - htup->t_hoff;
+	newlen = record->xl_len - SizeOfHeapInplace;
+	if (oldlen != newlen)
+		elog(PANIC, "heap_inplace_redo: wrong tuple length");
+
+	memcpy((char *) htup + htup->t_hoff,
+		   (char *) xlrec + SizeOfHeapInplace,
+		   newlen);
+
+	PageSetLSN(page, lsn);
+	PageSetTLI(page, ThisTimeLineID);
+	MarkBufferDirty(buffer);
+	UnlockReleaseBuffer(buffer);
+}
+
 void
 heap_redo(XLogRecPtr lsn, XLogRecord *record)
 {
@@ -3349,6 +3493,8 @@ heap_redo(XLogRecPtr lsn, XLogRecord *record)
 		heap_xlog_newpage(lsn, record);
 	else if (info == XLOG_HEAP_LOCK)
 		heap_xlog_lock(lsn, record);
+	else if (info == XLOG_HEAP_INPLACE)
+		heap_xlog_inplace(lsn, record);
 	else
 		elog(PANIC, "heap_redo: unknown op code %u", info);
 }
@@ -3442,6 +3588,13 @@ heap_desc(StringInfo buf, uint8 xl_info, char *rec)
 		appendStringInfo(buf, "%u ", xlrec->locking_xid);
 		out_target(buf, &(xlrec->target));
 	}
+	else if (info == XLOG_HEAP_INPLACE)
+	{
+		xl_heap_inplace *xlrec = (xl_heap_inplace *) rec;
+
+		appendStringInfo(buf, "inplace: ");
+		out_target(buf, &(xlrec->target));
+	}
 	else
 		appendStringInfo(buf, "UNKNOWN");
 }

src/backend/access/nbtree/nbtree.c

@@ -12,21 +12,18 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.148 2006/05/08 00:00:10 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.149 2006/05/10 23:18:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
 
 #include "access/genam.h"
-#include "access/heapam.h"
 #include "access/nbtree.h"
 #include "catalog/index.h"
 #include "commands/vacuum.h"
-#include "miscadmin.h"
 #include "storage/freespace.h"
-#include "storage/smgr.h"
-#include "utils/inval.h"
+#include "storage/lmgr.h"
 #include "utils/memutils.h"
 
 
@@ -84,6 +81,7 @@ btbuild(PG_FUNCTION_ARGS)
 	Relation	heap = (Relation) PG_GETARG_POINTER(0);
 	Relation	index = (Relation) PG_GETARG_POINTER(1);
 	IndexInfo  *indexInfo = (IndexInfo *) PG_GETARG_POINTER(2);
+	IndexBuildResult *result;
 	double		reltuples;
 	BTBuildState buildstate;
 
@@ -149,18 +147,20 @@ btbuild(PG_FUNCTION_ARGS)
 	/*
 	 * If we are reindexing a pre-existing index, it is critical to send out
 	 * a relcache invalidation SI message to ensure all backends re-read the
-	 * index metapage.  In most circumstances the update-stats operation will
-	 * cause that to happen, but at the moment there are corner cases where
-	 * no pg_class update will occur, so force an inval here.  XXX FIXME:
-	 * the upper levels of CREATE INDEX should handle the stats update as
-	 * well as guaranteeing relcache inval.
+	 * index metapage.  We expect that the caller will ensure that happens
+	 * (typically as a side effect of updating index stats, but it must
+	 * happen even if the stats don't change!)
 	 */
-	CacheInvalidateRelcache(index);
 
-	/* since we just counted the # of tuples, may as well update stats */
-	IndexCloseAndUpdateStats(heap, reltuples, index, buildstate.indtuples);
+	/*
+	 * Return statistics
+	 */
+	result = (IndexBuildResult *) palloc(sizeof(IndexBuildResult));
 
-	PG_RETURN_VOID();
+	result->heap_tuples = reltuples;
+	result->index_tuples = buildstate.indtuples;
+
+	PG_RETURN_POINTER(result);
 }
 
 /*

src/backend/bootstrap/bootstrap.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.214 2006/04/04 19:35:33 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.215 2006/05/10 23:18:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1173,11 +1173,12 @@ AddStr(char *str, int strlength, int mderef)
  *	index_register() -- record an index that has been set up for building
  *						later.
  *
- *		At bootstrap time, we define a bunch of indices on system catalogs.
- *		We postpone actually building the indices until just before we're
- *		finished with initialization, however.	This is because more classes
- *		and indices may be defined, and we want to be sure that all of them
- *		are present in the index.
+ *		At bootstrap time, we define a bunch of indexes on system catalogs.
+ *		We postpone actually building the indexes until just before we're
+ *		finished with initialization, however.	This is because the indexes
+ *		themselves have catalog entries, and those have to be included in the
+ *		indexes on those catalogs.  Doing it in two phases is the simplest
+ *		way of making sure the indexes have the right contents at the end.
  */
 void
 index_register(Oid heap,
@@ -1189,7 +1190,7 @@ index_register(Oid heap,
 
 	/*
 	 * XXX mao 10/31/92 -- don't gc index reldescs, associated info at
-	 * bootstrap time.	we'll declare the indices now, but want to create them
+	 * bootstrap time.	we'll declare the indexes now, but want to create them
 	 * later.
 	 */
 
@@ -1223,6 +1224,10 @@ index_register(Oid heap,
 	MemoryContextSwitchTo(oldcxt);
 }
 
+
+/*
+ * build_indices -- fill in all the indexes registered earlier
+ */
 void
 build_indices(void)
 {
@@ -1233,13 +1238,10 @@ build_indices(void)
 
 		heap = heap_open(ILHead->il_heap, NoLock);
 		ind = index_open(ILHead->il_ind);
-		index_build(heap, ind, ILHead->il_info);
 
-		/*
-		 * In normal processing mode, index_build would close the heap and
-		 * index, but in bootstrap mode it will not.
-		 */
+		index_build(heap, ind, ILHead->il_info, false, false);
 
-		/* XXX Probably we ought to close the heap and index here? */
+		index_close(ind);
+		heap_close(heap, NoLock);
 	}
 }

src/backend/catalog/heap.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.298 2006/04/30 01:08:06 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.299 2006/05/10 23:18:39 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -1921,17 +1921,14 @@ RelationTruncateIndexes(Oid heapId)
 		RelationTruncate(currentIndex, 0);
 
 		/* Initialize the index and rebuild */
-		index_build(heapRelation, currentIndex, indexInfo);
+		/* Note: we do not need to re-establish pkey or toast settings */
+		index_build(heapRelation, currentIndex, indexInfo, false, false);
 
-		/*
-		 * index_build will close both the heap and index relations (but not
-		 * give up the locks we hold on them).	We're done with this index,
-		 * but we must re-open the heap rel.
-		 */
-		heapRelation = heap_open(heapId, NoLock);
+		/* We're done with this index */
+		index_close(currentIndex);
 	}
 
-	/* Finish by closing the heap rel again */
+	/* And now done with the heap; but keep lock until commit */
 	heap_close(heapRelation, NoLock);
 }
 

src/backend/commands/indexcmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/indexcmds.c,v 1.138 2006/03/05 15:58:24 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/indexcmds.c,v 1.139 2006/05/10 23:18:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -397,17 +397,8 @@ DefineIndex(RangeVar *heapRelation,
 
 	index_create(relationId, indexRelationName, indexRelationId,
 				 indexInfo, accessMethodId, tablespaceId, classObjectId,
-				 primary, isconstraint,
+				 primary, false, isconstraint,
 				 allowSystemTableMods, skip_build);
-
-	/*
-	 * We update the relation's pg_class tuple even if it already has
-	 * relhasindex = true.	This is needed to cause a shared-cache-inval
-	 * message to be sent for the pg_class tuple, which will cause other
-	 * backends to flush their relcache entries and in particular their cached
-	 * lists of the indexes for this relation.
-	 */
-	setRelhasindex(relationId, true, primary, InvalidOid);
 }
 
 

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.183 2006/04/30 01:08:07 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.184 2006/05/10 23:18:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -6046,14 +6046,7 @@ AlterTableCreateToastTable(Oid relOid, bool silent)
 							   BTREE_AM_OID,
 							   rel->rd_rel->reltablespace,
 							   classObjectId,
-							   true, false, true, false);
-
-	/*
-	 * Update toast rel's pg_class entry to show that it has an index. The
-	 * index OID is stored into the reltoastidxid field for easy access by the
-	 * tuple toaster.
-	 */
-	setRelhasindex(toast_relid, true, true, toast_idxid);
+							   true, true, false, true, false);
 
 	/*
 	 * Store the toast table's OID in the parent relation's pg_class row

src/backend/commands/vacuum.c

@@ -13,7 +13,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.329 2006/05/03 22:45:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.330 2006/05/10 23:18:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -673,9 +673,10 @@ vacuum_set_xid_limits(VacuumStmt *vacstmt, bool sharedRel,
  *		doing ANALYZE, but we always update these stats.  This routine works
  *		for both index and heap relation entries in pg_class.
  *
- *		We violate no-overwrite semantics here by storing new values for the
- *		statistics columns directly into the pg_class tuple that's already on
- *		the page.  The reason for this is that if we updated these tuples in
+ *		We violate transaction semantics here by overwriting the rel's
+ *		existing pg_class tuple with the new values.  This is reasonably
+ *		safe since the new values are correct whether or not this transaction
+ *		commits.  The reason for this is that if we updated these tuples in
  *		the usual way, vacuuming pg_class itself wouldn't work very well ---
  *		by the time we got done with a vacuum cycle, most of the tuples in
  *		pg_class would've been obsoleted.  Of course, this only works for
@@ -689,59 +690,57 @@ vac_update_relstats(Oid relid, BlockNumber num_pages, double num_tuples,
 					bool hasindex)
 {
 	Relation	rd;
-	HeapTupleData rtup;
 	HeapTuple	ctup;
 	Form_pg_class pgcform;
-	Buffer		buffer;
+	bool		dirty;
 
-	/*
-	 * update number of tuples and number of pages in pg_class
-	 */
 	rd = heap_open(RelationRelationId, RowExclusiveLock);
 
-	ctup = SearchSysCache(RELOID,
+	/* Fetch a copy of the tuple to scribble on */
+	ctup = SearchSysCacheCopy(RELOID,
 							  ObjectIdGetDatum(relid),
 							  0, 0, 0);
 	if (!HeapTupleIsValid(ctup))
 		elog(ERROR, "pg_class entry for relid %u vanished during vacuuming",
 			 relid);
+	pgcform = (Form_pg_class) GETSTRUCT(ctup);
 
-	/* get the buffer cache tuple */
-	rtup.t_self = ctup->t_self;
-	ReleaseSysCache(ctup);
-	if (!heap_fetch(rd, SnapshotNow, &rtup, &buffer, false, NULL))
-		elog(ERROR, "pg_class entry for relid %u vanished during vacuuming",
-			 relid);
-
-	/* ensure no one else does this at the same time */
-	LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
+	/* Apply required updates, if any, to copied tuple */
 
-	/* overwrite the existing statistics in the tuple */
-	pgcform = (Form_pg_class) GETSTRUCT(&rtup);
+	dirty = false;
+	if (pgcform->relpages != (int32) num_pages)
+	{
 		pgcform->relpages = (int32) num_pages;
+		dirty = true;
+	}
+	if (pgcform->reltuples != (float4) num_tuples)
+	{
 		pgcform->reltuples = (float4) num_tuples;
+		dirty = true;
+	}
+	if (pgcform->relhasindex != hasindex)
+	{
 		pgcform->relhasindex = hasindex;
-
+		dirty = true;
+	}
 	/*
 	 * If we have discovered that there are no indexes, then there's no
 	 * primary key either.	This could be done more thoroughly...
 	 */
 	if (!hasindex)
+	{
+		if (pgcform->relhaspkey)
+		{
 			pgcform->relhaspkey = false;
-
-	MarkBufferDirty(buffer);
-
-	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
+			dirty = true;
+		}
+	}
 
 	/*
-	 * Invalidate the tuple in the catcaches; this also arranges to flush the
-	 * relation's relcache entry.  (If we fail to commit for some reason, no
-	 * flush will occur, but no great harm is done since there are no
-	 * noncritical state updates here.)
+	 * If anything changed, write out the tuple
 	 */
-	CacheInvalidateHeapTuple(rd, &rtup);
-
-	ReleaseBuffer(buffer);
+	if (dirty)
+		heap_inplace_update(rd, ctup);
 
 	heap_close(rd, RowExclusiveLock);
 }
@@ -753,10 +752,11 @@ vac_update_relstats(Oid relid, BlockNumber num_pages, double num_tuples,
  *		Update the whole-database statistics that are kept in its pg_database
  *		row, and the flat-file copy of pg_database.
  *
- *		We violate no-overwrite semantics here by storing new values for the
- *		statistics columns directly into the tuple that's already on the page.
- *		As with vac_update_relstats, this avoids leaving dead tuples behind
- *		after a VACUUM.
+ *		We violate transaction semantics here by overwriting the database's
+ *		existing pg_database tuple with the new values.  This is reasonably
+ *		safe since the new values are correct whether or not this transaction
+ *		commits.  As with vac_update_relstats, this avoids leaving dead tuples
+ *		behind after a VACUUM.
  *
  *		This routine is shared by full and lazy VACUUM.  Note that it is only
  *		applied after a database-wide VACUUM operation.
@@ -767,49 +767,24 @@ vac_update_dbstats(Oid dbid,
 				   TransactionId frozenXID)
 {
 	Relation	relation;
-	ScanKeyData entry[1];
-	SysScanDesc	scan;
 	HeapTuple	tuple;
-	Buffer		buf;
 	Form_pg_database dbform;
 
 	relation = heap_open(DatabaseRelationId, RowExclusiveLock);
 
-	ScanKeyInit(&entry[0],
-				ObjectIdAttributeNumber,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(dbid));
-
-	scan = systable_beginscan(relation, DatabaseOidIndexId, true,
-							  SnapshotNow, 1, entry);
-
-	tuple = systable_getnext(scan);
-
+	/* Fetch a copy of the tuple to scribble on */
+	tuple = SearchSysCacheCopy(DATABASEOID,
+							   ObjectIdGetDatum(dbid),
+							   0, 0, 0);
 	if (!HeapTupleIsValid(tuple))
 		elog(ERROR, "could not find tuple for database %u", dbid);
-
-	if (scan->irel)
-		buf = scan->iscan->xs_cbuf;
-	else
-		buf = scan->scan->rs_cbuf;
-
-	/* ensure no one else does this at the same time */
-	LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
-
 	dbform = (Form_pg_database) GETSTRUCT(tuple);
 
 	/* overwrite the existing statistics in the tuple */
 	dbform->datvacuumxid = vacuumXID;
 	dbform->datfrozenxid = frozenXID;
 
-	MarkBufferDirty(buf);
-
-	LockBuffer(buf, BUFFER_LOCK_UNLOCK);
-
-	/* invalidate the tuple in the cache so we'll see the change in cache */
-	CacheInvalidateHeapTuple(relation, tuple);
-
-	systable_endscan(scan);
+	heap_inplace_update(relation, tuple);
 
 	heap_close(relation, RowExclusiveLock);
 

src/include/access/genam.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/genam.h,v 1.59 2006/05/02 22:25:10 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/genam.h,v 1.60 2006/05/10 23:18:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -20,6 +20,15 @@
 #include "nodes/primnodes.h"
 
 
+/*
+ * Struct for statistics returned by ambuild
+ */
+typedef struct IndexBuildResult
+{
+	double		heap_tuples;	/* # of tuples seen in parent table */
+	double		index_tuples;	/* # of tuples inserted into index */
+} IndexBuildResult;
+
 /*
  * Struct for input arguments passed to ambulkdelete and amvacuumcleanup
  *

src/include/access/heapam.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/heapam.h,v 1.110 2006/04/24 22:24:58 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/heapam.h,v 1.111 2006/05/10 23:18:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -168,6 +168,7 @@ extern HTSU_Result heap_lock_tuple(Relation relation, HeapTuple tuple,
 				Buffer *buffer, ItemPointer ctid,
 				TransactionId *update_xmax, CommandId cid,
 				LockTupleMode mode, bool nowait);
+extern void heap_inplace_update(Relation relation, HeapTuple tuple);
 
 extern Oid	simple_heap_insert(Relation relation, HeapTuple tup);
 extern void simple_heap_delete(Relation relation, ItemPointer tid);

src/include/access/htup.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.81 2006/03/05 15:58:53 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.82 2006/05/10 23:18:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -444,7 +444,7 @@ typedef HeapTupleData *HeapTuple;
 #define XLOG_HEAP_CLEAN		0x40
 #define XLOG_HEAP_NEWPAGE	0x50
 #define XLOG_HEAP_LOCK		0x60
-/* opcode 0x70 still free */
+#define XLOG_HEAP_INPLACE	0x70
 #define XLOG_HEAP_OPMASK	0x70
 /*
  * When we insert 1st item on new page in INSERT/UPDATE
@@ -545,4 +545,13 @@ typedef struct xl_heap_lock
 
 #define SizeOfHeapLock	(offsetof(xl_heap_lock, shared_lock) + sizeof(bool))
 
+/* This is what we need to know about in-place update */
+typedef struct xl_heap_inplace
+{
+	xl_heaptid	target;			/* updated tuple id */
+	/* TUPLE DATA FOLLOWS AT END OF STRUCT */
+} xl_heap_inplace;
+
+#define SizeOfHeapInplace	(offsetof(xl_heap_inplace, target) + SizeOfHeapTid)
+
 #endif   /* HTUP_H */

src/include/catalog/index.h

 /*-------------------------------------------------------------------------
  *
  * index.h
- *	  prototypes for index.c.
+ *	  prototypes for catalog/index.c.
  *
  *
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/index.h,v 1.65 2006/03/05 15:58:54 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/index.h,v 1.66 2006/05/10 23:18:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -37,7 +37,8 @@ extern Oid index_create(Oid heapRelationId,
 			 Oid accessMethodObjectId,
 			 Oid tableSpaceId,
 			 Oid *classObjectId,
-			 bool primary,
+			 bool isprimary,
+			 bool istoast,
 			 bool isconstraint,
 			 bool allow_system_table_mods,
 			 bool skip_build);
@@ -52,16 +53,13 @@ extern void FormIndexDatum(IndexInfo *indexInfo,
 			   Datum *values,
 			   bool *isnull);
 
-extern void IndexCloseAndUpdateStats(Relation heap, double heapTuples,
-						 Relation index, double indexTuples);
-
-extern void setRelhasindex(Oid relid, bool hasindex,
-			   bool isprimary, Oid reltoastidxid);
-
 extern void setNewRelfilenode(Relation relation);
 
-extern void index_build(Relation heapRelation, Relation indexRelation,
-			IndexInfo *indexInfo);
+extern void index_build(Relation heapRelation,
+			Relation indexRelation,
+			IndexInfo *indexInfo,
+			bool isprimary,
+			bool istoast);
 
 extern double IndexBuildHeapScan(Relation heapRelation,
 				   Relation indexRelation,

src/include/catalog/pg_proc.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.410 2006/05/02 22:25:10 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.411 2006/05/10 23:18:39 tgl Exp $
  *
  * NOTES
  *	  The script catalog/genbki.sh reads this file and generates .bki
@@ -672,7 +672,7 @@ DATA(insert OID = 336 (  btmarkpos		   PGNSP PGUID 12 f f t f v 1 2278 "2281" _n
 DESCR("btree(internal)");
 DATA(insert OID = 337 (  btrestrpos		   PGNSP PGUID 12 f f t f v 1 2278 "2281" _null_ _null_ _null_	btrestrpos - _null_ ));
 DESCR("btree(internal)");
-DATA(insert OID = 338 (  btbuild		   PGNSP PGUID 12 f f t f v 3 2278 "2281 2281 2281" _null_ _null_ _null_ btbuild - _null_ ));
+DATA(insert OID = 338 (  btbuild		   PGNSP PGUID 12 f f t f v 3 2281 "2281 2281 2281" _null_ _null_ _null_ btbuild - _null_ ));
 DESCR("btree(internal)");
 DATA(insert OID = 332 (  btbulkdelete	   PGNSP PGUID 12 f f t f v 4 2281 "2281 2281 2281 2281" _null_ _null_ _null_ btbulkdelete - _null_ ));
 DESCR("btree(internal)");
@@ -789,7 +789,7 @@ DATA(insert OID = 446 (  hashmarkpos	   PGNSP PGUID 12 f f t f v 1 2278 "2281" _
 DESCR("hash(internal)");
 DATA(insert OID = 447 (  hashrestrpos	   PGNSP PGUID 12 f f t f v 1 2278 "2281" _null_ _null_ _null_	hashrestrpos - _null_ ));
 DESCR("hash(internal)");
-DATA(insert OID = 448 (  hashbuild		   PGNSP PGUID 12 f f t f v 3 2278 "2281 2281 2281" _null_ _null_ _null_ hashbuild - _null_ ));
+DATA(insert OID = 448 (  hashbuild		   PGNSP PGUID 12 f f t f v 3 2281 "2281 2281 2281" _null_ _null_ _null_ hashbuild - _null_ ));
 DESCR("hash(internal)");
 DATA(insert OID = 442 (  hashbulkdelete    PGNSP PGUID 12 f f t f v 4 2281 "2281 2281 2281 2281" _null_ _null_ _null_ hashbulkdelete - _null_ ));
 DESCR("hash(internal)");
@@ -1055,7 +1055,7 @@ DATA(insert OID = 780 (  gistmarkpos	   PGNSP PGUID 12 f f t f v 1 2278 "2281" _
 DESCR("gist(internal)");
 DATA(insert OID = 781 (  gistrestrpos	   PGNSP PGUID 12 f f t f v 1 2278 "2281" _null_ _null_ _null_	gistrestrpos - _null_ ));
 DESCR("gist(internal)");
-DATA(insert OID = 782 (  gistbuild		   PGNSP PGUID 12 f f t f v 3 2278 "2281 2281 2281" _null_ _null_ _null_ gistbuild - _null_ ));
+DATA(insert OID = 782 (  gistbuild		   PGNSP PGUID 12 f f t f v 3 2281 "2281 2281 2281" _null_ _null_ _null_ gistbuild - _null_ ));
 DESCR("gist(internal)");
 DATA(insert OID = 776 (  gistbulkdelete    PGNSP PGUID 12 f f t f v 4 2281 "2281 2281 2281 2281" _null_ _null_ _null_ gistbulkdelete - _null_ ));
 DESCR("gist(internal)");
@@ -3833,7 +3833,7 @@ DATA(insert OID = 2736 (  ginmarkpos	   PGNSP PGUID 12 f f t f v 1 2278 "2281" _
 DESCR("gin(internal)");
 DATA(insert OID = 2737 (  ginrestrpos	   PGNSP PGUID 12 f f t f v 1 2278 "2281" _null_ _null_ _null_	ginrestrpos - _null_ ));
 DESCR("gin(internal)");
-DATA(insert OID = 2738 (  ginbuild		   PGNSP PGUID 12 f f t f v 3 2278 "2281 2281 2281" _null_ _null_ _null_ ginbuild - _null_ ));
+DATA(insert OID = 2738 (  ginbuild		   PGNSP PGUID 12 f f t f v 3 2281 "2281 2281 2281" _null_ _null_ _null_ ginbuild - _null_ ));
 DESCR("gin(internal)");
 DATA(insert OID = 2739 (  ginbulkdelete    PGNSP PGUID 12 f f t f v 4 2281 "2281 2281 2281 2281" _null_ _null_ _null_ ginbulkdelete - _null_ ));
 DESCR("gin(internal)");