Get rid of rd_nblocks field in relcache entries. Turns out this was

costing us lots more to maintain than it was worth.  On shared tables
it was of exactly zero benefit because we couldn't trust it to be
up to date.  On temp tables it sometimes saved an lseek, but not often
enough to be worth getting excited about.  And the real problem was that
we forced an lseek on every relcache flush in order to update the field.
So all in all it seems best to lose the complexity.

3 files changed, 5 insertions, 5 deletions

diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 746b795b26e..b6ca7e43a62 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.34 2003/11/29 22:40:55 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.35 2004/05/08 19:09:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -25,6 +25,7 @@ typedef struct HeapScanDescData
 	Snapshot	rs_snapshot;	/* snapshot to see */
 	int			rs_nkeys;		/* number of scan keys */
 	ScanKey		rs_key;			/* array of scan key descriptors */
+	BlockNumber rs_nblocks;		/* number of blocks to scan */
 
 	/* scan current state */
 	HeapTupleData rs_ctup;		/* current tuple in scan, if any */
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 1cd16a51534..0aab9ad24f4 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.78 2004/04/25 23:50:58 neilc Exp $
+ * $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.79 2004/05/08 19:09:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -156,7 +156,7 @@ extern void AtEOXact_Buffers(bool isCommit);
 extern void FlushBufferPool(void);
 extern BlockNumber BufferGetBlockNumber(Buffer buffer);
 extern BlockNumber RelationGetNumberOfBlocks(Relation relation);
-extern void RelationUpdateNumberOfBlocks(Relation relation);
+extern void RelationTruncate(Relation rel, BlockNumber nblocks);
 extern int	FlushRelationBuffers(Relation rel, BlockNumber firstDelBlock);
 extern void DropRelationBuffers(Relation rel);
 extern void DropRelFileNodeBuffers(RelFileNode rnode, bool istemp);
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 8532c5a737a..e5008e56ea5 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.73 2004/02/10 01:55:27 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.74 2004/05/08 19:09:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -107,7 +107,6 @@ typedef struct RelationData
 	RelFileNode rd_node;		/* relation physical identifier */
 	/* use "struct" here to avoid needing to include smgr.h: */
 	struct SMgrRelationData *rd_smgr; /* cached file handle, or NULL */
-	BlockNumber rd_nblocks;		/* number of blocks in rel */
 	BlockNumber rd_targblock;	/* current insertion target block, or
 								 * InvalidBlockNumber */
 	int			rd_refcnt;		/* reference count */