Fix up pgstats counting of live and dead tuples to recognize that committed

and aborted transactions have different effects; also teach it not to assume
that prepared transactions are always committed.

Along the way, simplify the pgstats API by tying counting directly to
Relations; I cannot detect any redeeming social value in having stats
pointers in HeapScanDesc and IndexScanDesc structures.  And fix a few
corner cases in which counts might be missed because the relation's
pgstat_info pointer hadn't been set.

src/backend/access/gin/ginscan.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *			$PostgreSQL: pgsql/src/backend/access/gin/ginscan.c,v 1.9 2007/01/31 15:09:45 teodor Exp $
+ *			$PostgreSQL: pgsql/src/backend/access/gin/ginscan.c,v 1.10 2007/05/27 03:50:38 tgl Exp $
  *-------------------------------------------------------------------------
  */
 
@@ -189,7 +189,7 @@ newScanKey(IndexScanDesc scan)
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("GIN index does not support search with void query")));
 
-	pgstat_count_index_scan(&scan->xs_pgstat_info);
+	pgstat_count_index_scan(scan->indexRelation);
 }
 
 Datum

src/backend/access/gist/gistget.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.65 2007/04/06 22:33:41 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.66 2007/05/27 03:50:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -165,7 +165,7 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids,
 		stk->next = NULL;
 		stk->block = GIST_ROOT_BLKNO;
 
-		pgstat_count_index_scan(&scan->xs_pgstat_info);
+		pgstat_count_index_scan(scan->indexRelation);
 	}
 	else if (so->curbuf == InvalidBuffer)
 	{

src/backend/access/hash/hashsearch.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/hash/hashsearch.c,v 1.49 2007/05/03 16:45:58 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/hash/hashsearch.c,v 1.50 2007/05/27 03:50:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -127,7 +127,7 @@ _hash_first(IndexScanDesc scan, ScanDirection dir)
 	ItemPointer current;
 	OffsetNumber offnum;
 
-	pgstat_count_index_scan(&scan->xs_pgstat_info);
+	pgstat_count_index_scan(rel);
 
 	current = &(so->hashso_curpos);
 	ItemPointerSetInvalid(current);

src/backend/access/heap/heapam.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.232 2007/04/08 01:26:27 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.233 2007/05/27 03:50:38 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -100,7 +100,7 @@ initscan(HeapScanDesc scan, ScanKey key)
 	if (key != NULL)
 		memcpy(scan->rs_key, key, scan->rs_nkeys * sizeof(ScanKeyData));
 
-	pgstat_count_heap_scan(&scan->rs_pgstat_info);
+	pgstat_count_heap_scan(scan->rs_rd);
 }
 
 /*
@@ -701,6 +701,8 @@ relation_open(Oid relationId, LOCKMODE lockmode)
 	if (!RelationIsValid(r))
 		elog(ERROR, "could not open relation with OID %u", relationId);
 
+	pgstat_initstats(r);
+
 	return r;
 }
 
@@ -743,6 +745,8 @@ try_relation_open(Oid relationId, LOCKMODE lockmode)
 	if (!RelationIsValid(r))
 		elog(ERROR, "could not open relation with OID %u", relationId);
 
+	pgstat_initstats(r);
+
 	return r;
 }
 
@@ -787,6 +791,8 @@ relation_open_nowait(Oid relationId, LOCKMODE lockmode)
 	if (!RelationIsValid(r))
 		elog(ERROR, "could not open relation with OID %u", relationId);
 
+	pgstat_initstats(r);
+
 	return r;
 }
 
@@ -873,8 +879,6 @@ heap_open(Oid relationId, LOCKMODE lockmode)
 				 errmsg("\"%s\" is a composite type",
 						RelationGetRelationName(r))));
 
-	pgstat_initstats(&r->pgstat_info, r);
-
 	return r;
 }
 
@@ -903,8 +907,6 @@ heap_openrv(const RangeVar *relation, LOCKMODE lockmode)
 				 errmsg("\"%s\" is a composite type",
 						RelationGetRelationName(r))));
 
-	pgstat_initstats(&r->pgstat_info, r);
-
 	return r;
 }
 
@@ -954,8 +956,6 @@ heap_beginscan(Relation relation, Snapshot snapshot,
 	else
 		scan->rs_key = NULL;
 
-	pgstat_initstats(&scan->rs_pgstat_info, relation);
-
 	initscan(scan, key);
 
 	return scan;
@@ -1059,7 +1059,7 @@ heap_getnext(HeapScanDesc scan, ScanDirection direction)
 	 */
 	HEAPDEBUG_3;				/* heap_getnext returning tuple */
 
-	pgstat_count_heap_getnext(&scan->rs_pgstat_info);
+	pgstat_count_heap_getnext(scan->rs_rd);
 
 	return &(scan->rs_ctup);
 }
@@ -1086,6 +1086,10 @@ heap_getnext(HeapScanDesc scan, ScanDirection direction)
  * and return it in *userbuf (so the caller must eventually unpin it); when
  * keep_buf = false, the pin is released and *userbuf is set to InvalidBuffer.
  *
+ * stats_relation is the relation to charge the heap_fetch operation against
+ * for statistical purposes.  (This could be the heap rel itself, an
+ * associated index, or NULL to not count the fetch at all.)
+ *
  * It is somewhat inconsistent that we ereport() on invalid block number but
  * return false on invalid item number.  There are a couple of reasons though.
  * One is that the caller can relatively easily check the block number for
@@ -1101,12 +1105,12 @@ heap_fetch(Relation relation,
 		   HeapTuple tuple,
 		   Buffer *userbuf,
 		   bool keep_buf,
-		   PgStat_Info *pgstat_info)
+		   Relation stats_relation)
 {
 	/* Assume *userbuf is undefined on entry */
 	*userbuf = InvalidBuffer;
 	return heap_release_fetch(relation, snapshot, tuple,
-							  userbuf, keep_buf, pgstat_info);
+							  userbuf, keep_buf, stats_relation);
 }
 
 /*
@@ -1125,7 +1129,7 @@ heap_release_fetch(Relation relation,
 				   HeapTuple tuple,
 				   Buffer *userbuf,
 				   bool keep_buf,
-				   PgStat_Info *pgstat_info)
+				   Relation stats_relation)
 {
 	ItemPointer tid = &(tuple->t_self);
 	ItemId		lp;
@@ -1210,9 +1214,9 @@ heap_release_fetch(Relation relation,
 		 */
 		*userbuf = buffer;
 
-		/* Count the successful fetch in *pgstat_info, if given. */
-		if (pgstat_info != NULL)
-			pgstat_count_heap_fetch(pgstat_info);
+		/* Count the successful fetch against appropriate rel, if any */
+		if (stats_relation != NULL)
+			pgstat_count_heap_fetch(stats_relation);
 
 		return true;
 	}
@@ -1517,7 +1521,7 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid,
 	 */
 	CacheInvalidateHeapTuple(relation, heaptup);
 
-	pgstat_count_heap_insert(&relation->pgstat_info);
+	pgstat_count_heap_insert(relation);
 
 	/*
 	 * If heaptup is a private copy, release it.  Don't forget to copy t_self
@@ -1807,7 +1811,7 @@ l1:
 	if (have_tuple_lock)
 		UnlockTuple(relation, &(tp.t_self), ExclusiveLock);
 
-	pgstat_count_heap_delete(&relation->pgstat_info);
+	pgstat_count_heap_delete(relation);
 
 	return HeapTupleMayBeUpdated;
 }
@@ -2269,7 +2273,7 @@ l2:
 	if (have_tuple_lock)
 		UnlockTuple(relation, &(oldtup.t_self), ExclusiveLock);
 
-	pgstat_count_heap_update(&relation->pgstat_info);
+	pgstat_count_heap_update(relation);
 
 	/*
 	 * If heaptup is a private copy, release it.  Don't forget to copy t_self

src/backend/access/index/genam.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/index/genam.c,v 1.61 2007/01/20 18:43:35 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/index/genam.c,v 1.62 2007/05/27 03:50:38 tgl Exp $
  *
  * NOTES
  *	  many of the old access method routines have been turned into
@@ -96,8 +96,6 @@ RelationGetIndexScan(Relation indexRelation,
 	scan->xs_ctup.t_data = NULL;
 	scan->xs_cbuf = InvalidBuffer;
 
-	pgstat_initstats(&scan->xs_pgstat_info, indexRelation);
-
 	/*
 	 * Let the AM fill in the key and any opaque data it wants.
 	 */

src/backend/access/index/indexam.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.97 2007/01/05 22:19:23 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.98 2007/05/27 03:50:38 tgl Exp $
  *
  * INTERFACE ROUTINES
  *		index_open		- open an index relation by relation OID
@@ -145,8 +145,6 @@ index_open(Oid relationId, LOCKMODE lockmode)
 				 errmsg("\"%s\" is not an index",
 						RelationGetRelationName(r))));
 
-	pgstat_initstats(&r->pgstat_info, r);
-
 	return r;
 }
 
@@ -433,14 +431,14 @@ index_getnext(IndexScanDesc scan, ScanDirection direction)
 			return NULL;		/* failure exit */
 		}
 
-		pgstat_count_index_tuples(&scan->xs_pgstat_info, 1);
+		pgstat_count_index_tuples(scan->indexRelation, 1);
 
 		/*
 		 * Fetch the heap tuple and see if it matches the snapshot.
 		 */
 		if (heap_release_fetch(scan->heapRelation, scan->xs_snapshot,
 							   heapTuple, &scan->xs_cbuf, true,
-							   &scan->xs_pgstat_info))
+							   scan->indexRelation))
 			break;
 
 		/* Skip if no undeleted tuple at this location */
@@ -502,7 +500,7 @@ index_getnext_indexitem(IndexScanDesc scan,
 									   Int32GetDatum(direction)));
 
 	if (found)
-		pgstat_count_index_tuples(&scan->xs_pgstat_info, 1);
+		pgstat_count_index_tuples(scan->indexRelation, 1);
 
 	return found;
 }
@@ -543,7 +541,7 @@ index_getmulti(IndexScanDesc scan,
 									   Int32GetDatum(max_tids),
 									   PointerGetDatum(returned_tids)));
 
-	pgstat_count_index_tuples(&scan->xs_pgstat_info, *returned_tids);
+	pgstat_count_index_tuples(scan->indexRelation, *returned_tids);
 
 	return found;
 }

src/backend/access/nbtree/nbtsearch.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.112 2007/04/06 22:33:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.113 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -453,7 +453,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
 	int			i;
 	StrategyNumber strat_total;
 
-	pgstat_count_index_scan(&scan->xs_pgstat_info);
+	pgstat_count_index_scan(rel);
 
 	/*
 	 * Examine the scan keys and eliminate any redundant keys; also mark the

src/backend/access/transam/twophase.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *		$PostgreSQL: pgsql/src/backend/access/transam/twophase.c,v 1.30 2007/04/30 21:01:52 tgl Exp $
+ *		$PostgreSQL: pgsql/src/backend/access/transam/twophase.c,v 1.31 2007/05/27 03:50:39 tgl Exp $
  *
  * NOTES
  *		Each global transaction is associated with a global transaction
@@ -1211,7 +1211,8 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
 	else
 		ProcessRecords(bufptr, xid, twophase_postabort_callbacks);
 
-	pgstat_count_xact_commit();
+	/* Count the prepared xact as committed or aborted */
+	AtEOXact_PgStat(isCommit);
 
 	/*
 	 * And now we can clean up our mess.

src/backend/access/transam/twophase_rmgr.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/transam/twophase_rmgr.c,v 1.4 2007/01/05 22:19:23 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/transam/twophase_rmgr.c,v 1.5 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,6 +16,7 @@
 
 #include "access/twophase_rmgr.h"
 #include "commands/async.h"
+#include "pgstat.h"
 #include "storage/lock.h"
 #include "utils/flatfiles.h"
 #include "utils/inval.h"
@@ -27,7 +28,8 @@ const TwoPhaseCallback twophase_recover_callbacks[TWOPHASE_RM_MAX_ID + 1] =
 	lock_twophase_recover,		/* Lock */
 	NULL,						/* Inval */
 	NULL,						/* flat file update */
-	NULL						/* notify/listen */
+	NULL,						/* notify/listen */
+	NULL						/* pgstat */
 };
 
 const TwoPhaseCallback twophase_postcommit_callbacks[TWOPHASE_RM_MAX_ID + 1] =
@@ -36,7 +38,8 @@ const TwoPhaseCallback twophase_postcommit_callbacks[TWOPHASE_RM_MAX_ID + 1] =
 	lock_twophase_postcommit,	/* Lock */
 	inval_twophase_postcommit,	/* Inval */
 	flatfile_twophase_postcommit,		/* flat file update */
-	notify_twophase_postcommit	/* notify/listen */
+	notify_twophase_postcommit,	/* notify/listen */
+	pgstat_twophase_postcommit	/* pgstat */
 };
 
 const TwoPhaseCallback twophase_postabort_callbacks[TWOPHASE_RM_MAX_ID + 1] =
@@ -45,5 +48,6 @@ const TwoPhaseCallback twophase_postabort_callbacks[TWOPHASE_RM_MAX_ID + 1] =
 	lock_twophase_postabort,	/* Lock */
 	NULL,						/* Inval */
 	NULL,						/* flat file update */
-	NULL						/* notify/listen */
+	NULL,						/* notify/listen */
+	pgstat_twophase_postabort	/* pgstat */
 };

src/backend/access/transam/xact.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.242 2007/04/30 21:01:52 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.243 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1661,8 +1661,7 @@ CommitTransaction(void)
 	AtEOXact_Files();
 	AtEOXact_ComboCid();
 	AtEOXact_HashTables(true);
-	pgstat_clear_snapshot();
-	pgstat_count_xact_commit();
+	AtEOXact_PgStat(true);
 	pgstat_report_txn_timestamp(0);
 
 	CurrentResourceOwner = NULL;
@@ -1796,6 +1795,7 @@ PrepareTransaction(void)
 	AtPrepare_UpdateFlatFiles();
 	AtPrepare_Inval();
 	AtPrepare_Locks();
+	AtPrepare_PgStat();
 
 	/*
 	 * Here is where we really truly prepare.
@@ -1853,6 +1853,8 @@ PrepareTransaction(void)
 
 	/* notify and flatfiles don't need a postprepare call */
 
+	PostPrepare_PgStat();
+
 	PostPrepare_Inval();
 
 	PostPrepare_smgr();
@@ -1880,7 +1882,7 @@ PrepareTransaction(void)
 	AtEOXact_Files();
 	AtEOXact_ComboCid();
 	AtEOXact_HashTables(true);
-	pgstat_clear_snapshot();
+	/* don't call AtEOXact_PgStat here */
 
 	CurrentResourceOwner = NULL;
 	ResourceOwnerDelete(TopTransactionResourceOwner);
@@ -2035,8 +2037,7 @@ AbortTransaction(void)
 	AtEOXact_Files();
 	AtEOXact_ComboCid();
 	AtEOXact_HashTables(false);
-	pgstat_clear_snapshot();
-	pgstat_count_xact_rollback();
+	AtEOXact_PgStat(false);
 	pgstat_report_txn_timestamp(0);
 
 	/*
@@ -3749,6 +3750,7 @@ CommitSubTransaction(void)
 	AtEOSubXact_Files(true, s->subTransactionId,
 					  s->parent->subTransactionId);
 	AtEOSubXact_HashTables(true, s->nestingLevel);
+	AtEOSubXact_PgStat(true, s->nestingLevel);
 
 	/*
 	 * We need to restore the upper transaction's read-only state, in case the
@@ -3861,6 +3863,7 @@ AbortSubTransaction(void)
 		AtEOSubXact_Files(false, s->subTransactionId,
 						  s->parent->subTransactionId);
 		AtEOSubXact_HashTables(false, s->nestingLevel);
+		AtEOSubXact_PgStat(false, s->nestingLevel);
 	}
 
 	/*

src/backend/executor/nodeBitmapHeapscan.c

@@ -21,7 +21,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeBitmapHeapscan.c,v 1.16 2007/01/05 22:19:28 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeBitmapHeapscan.c,v 1.17 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -189,7 +189,7 @@ BitmapHeapNext(BitmapHeapScanState *node)
 		scan->rs_ctup.t_len = ItemIdGetLength(lp);
 		ItemPointerSet(&scan->rs_ctup.t_self, tbmres->blockno, targoffset);
 
-		pgstat_count_heap_fetch(&scan->rs_pgstat_info);
+		pgstat_count_heap_fetch(scan->rs_rd);
 
 		/*
 		 * Set up the result slot to point to this tuple. Note that the slot
@@ -389,7 +389,7 @@ ExecBitmapHeapReScan(BitmapHeapScanState *node, ExprContext *exprCtxt)
 	heap_rescan(node->ss.ss_currentScanDesc, NULL);
 
 	/* undo bogus "seq scan" count (see notes in ExecInitBitmapHeapScan) */
-	pgstat_discount_heap_scan(&node->ss.ss_currentScanDesc->rs_pgstat_info);
+	pgstat_discount_heap_scan(node->ss.ss_currentScanDesc->rs_rd);
 
 	if (node->tbm)
 		tbm_free(node->tbm);
@@ -535,7 +535,7 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
 	 * when we actually aren't doing any such thing.  Reverse out the added
 	 * scan count.	(Eventually we may want to count bitmap scans separately.)
 	 */
-	pgstat_discount_heap_scan(&scanstate->ss.ss_currentScanDesc->rs_pgstat_info);
+	pgstat_discount_heap_scan(scanstate->ss.ss_currentScanDesc->rs_rd);
 
 	/*
 	 * get the scan type from the relation descriptor.

src/backend/postmaster/bgwriter.c

@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.37 2007/03/30 18:34:55 mha Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.38 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -125,13 +125,6 @@ typedef struct
 
 static BgWriterShmemStruct *BgWriterShmem;
 
-/*
- * BgWriter statistics counters.
- * Stored directly in a stats message structure so it can be sent
- * without needing to copy things around.
- */
-PgStat_MsgBgWriter BgWriterStats;
-
 /*
  * GUC parameters
  */
@@ -250,11 +243,6 @@ BackgroundWriterMain(void)
 											 ALLOCSET_DEFAULT_MAXSIZE);
 	MemoryContextSwitchTo(bgwriter_context);
 
-	/*
-	 * Initialize statistics counters to zero
-	 */
-	memset(&BgWriterStats, 0, sizeof(BgWriterStats));
-
 	/*
 	 * If an exception is encountered, processing resumes here.
 	 *

src/backend/storage/buffer/bufmgr.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.218 2007/05/02 23:34:48 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.219 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -88,12 +88,6 @@ static bool IsForInput;
 /* local state for LockBufferForCleanup */
 static volatile BufferDesc *PinCountWaitBuf = NULL;
 
-/*
- * Global statistics for the bgwriter. The contents of this variable
- * only makes sense in the bgwriter process.
- */
-extern PgStat_MsgBgWriter BgWriterStats;
-
 
 static Buffer ReadBuffer_common(Relation reln, BlockNumber blockNum,
 								bool zeroPage);
@@ -174,7 +168,7 @@ ReadBuffer_common(Relation reln, BlockNumber blockNum, bool zeroPage)
 	if (isExtend)
 		blockNum = smgrnblocks(reln->rd_smgr);
 
-	pgstat_count_buffer_read(&reln->pgstat_info, reln);
+	pgstat_count_buffer_read(reln);
 
 	if (isLocalBuf)
 	{
@@ -204,7 +198,7 @@ ReadBuffer_common(Relation reln, BlockNumber blockNum, bool zeroPage)
 		if (!isExtend)
 		{
 			/* Just need to update stats before we exit */
-			pgstat_count_buffer_hit(&reln->pgstat_info, reln);
+			pgstat_count_buffer_hit(reln);
 
 			if (VacuumCostActive)
 				VacuumCostBalance += VacuumCostPageHit;

src/backend/utils/cache/relcache.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.260 2007/05/02 21:08:46 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.261 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1802,6 +1802,7 @@ RelationClearRelation(Relation relation, bool rebuild)
 		int			old_refcnt = relation->rd_refcnt;
 		SubTransactionId old_createSubid = relation->rd_createSubid;
 		SubTransactionId old_newRelfilenodeSubid = relation->rd_newRelfilenodeSubid;
+		struct PgStat_TableStatus *old_pgstat_info = relation->pgstat_info;
 		TupleDesc	old_att = relation->rd_att;
 		RuleLock   *old_rules = relation->rd_rules;
 		MemoryContext old_rulescxt = relation->rd_rulescxt;
@@ -1821,6 +1822,7 @@ RelationClearRelation(Relation relation, bool rebuild)
 		relation->rd_refcnt = old_refcnt;
 		relation->rd_createSubid = old_createSubid;
 		relation->rd_newRelfilenodeSubid = old_newRelfilenodeSubid;
+		relation->pgstat_info = old_pgstat_info;
 
 		if (equalTupleDescs(old_att, relation->rd_att))
 		{

src/include/access/heapam.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/heapam.h,v 1.123 2007/04/08 01:26:33 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/heapam.h,v 1.124 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -147,10 +147,10 @@ extern HeapTuple heap_getnext(HeapScanDesc scan, ScanDirection direction);
 
 extern bool heap_fetch(Relation relation, Snapshot snapshot,
 		   HeapTuple tuple, Buffer *userbuf, bool keep_buf,
-		   PgStat_Info *pgstat_info);
+		   Relation stats_relation);
 extern bool heap_release_fetch(Relation relation, Snapshot snapshot,
 				   HeapTuple tuple, Buffer *userbuf, bool keep_buf,
-				   PgStat_Info *pgstat_info);
+				   Relation stats_relation);
 
 extern void heap_get_latest_tid(Relation relation, Snapshot snapshot,
 					ItemPointer tid);

src/include/access/relscan.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.52 2007/01/20 18:43:35 neilc Exp $
+ * $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.53 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -37,8 +37,6 @@ typedef struct HeapScanDescData
 	/* NB: if rs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
 	ItemPointerData rs_mctid;	/* marked scan position, if any */
 
-	PgStat_Info rs_pgstat_info; /* statistics collector hook */
-
 	/* these fields only used in page-at-a-time mode */
 	int			rs_cindex;		/* current tuple's index in vistuples */
 	int			rs_mindex;		/* marked tuple's saved index */
@@ -78,8 +76,6 @@ typedef struct IndexScanDescData
 	HeapTupleData xs_ctup;		/* current heap tuple, if any */
 	Buffer		xs_cbuf;		/* current heap buffer in scan, if any */
 	/* NB: if xs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
-
-	PgStat_Info xs_pgstat_info; /* statistics collector hook */
 } IndexScanDescData;
 
 typedef IndexScanDescData *IndexScanDesc;

src/include/access/twophase_rmgr.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/twophase_rmgr.h,v 1.4 2007/01/05 22:19:51 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/twophase_rmgr.h,v 1.5 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -26,7 +26,8 @@ typedef uint8 TwoPhaseRmgrId;
 #define TWOPHASE_RM_INVAL_ID		2
 #define TWOPHASE_RM_FLATFILES_ID	3
 #define TWOPHASE_RM_NOTIFY_ID		4
-#define TWOPHASE_RM_MAX_ID			TWOPHASE_RM_NOTIFY_ID
+#define TWOPHASE_RM_PGSTAT_ID		5
+#define TWOPHASE_RM_MAX_ID			TWOPHASE_RM_PGSTAT_ID
 
 extern const TwoPhaseCallback twophase_recover_callbacks[];
 extern const TwoPhaseCallback twophase_postcommit_callbacks[];

src/include/utils/rel.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.100 2007/03/29 00:15:39 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.101 2007/05/27 03:50:39 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -89,15 +89,6 @@ typedef struct TriggerDesc
 } TriggerDesc;
 
 
-/*
- * Same for the statistics collector data in Relation and scan data.
- */
-typedef struct PgStat_Info
-{
-	void	   *tabentry;
-} PgStat_Info;
-
-
 /*
  * Cached lookup information for the index access method functions defined
  * by the pg_am row associated with an index relation.
@@ -200,8 +191,8 @@ typedef struct RelationData
 	List	   *rd_indpred;		/* index predicate tree, if any */
 	void	   *rd_amcache;		/* available for use by index AM */
 
-	/* statistics collection area */
-	PgStat_Info pgstat_info;
+	/* use "struct" here to avoid needing to include pgstat.h: */
+	struct PgStat_TableStatus *pgstat_info;	/* statistics collection area */
 } RelationData;
 
 typedef RelationData *Relation;