Remove RelationGetBufferWithBuffer(), which is horribly confused about

appropriate pin-count manipulation, and instead use ReleaseAndReadBuffer.
Make use of the fact that the passed-in buffer (if there is one) must
be pinned to avoid grabbing the bufmgr spinlock when we are able to
return this same buffer.  Eliminate unnecessary 'previous tuple' and
'next tuple' fields of HeapScanDesc and IndexScanDesc, thereby removing
a whole lot of bookkeeping from heap_getnext() and related routines.

2 files changed, 10 insertions, 17 deletions

diff --git a/src/include/storage/buf.h b/src/include/storage/buf.h
index c65e4cc9975..f31d5d5cc8d 100644
--- a/src/include/storage/buf.h
+++ b/src/include/storage/buf.h
@@ -7,17 +7,22 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: buf.h,v 1.8 2001/01/24 19:43:27 momjian Exp $
+ * $Id: buf.h,v 1.9 2001/06/09 18:16:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #ifndef BUF_H
 #define BUF_H
 
-#define InvalidBuffer	(0)
-#define UnknownBuffer	(-99999)
+/*
+ * Buffer identifiers.
+ *
+ * Zero is invalid, positive is the index of a shared buffer (1..NBuffers),
+ * negative is the index of a local buffer (-1 .. -NLocBuffer).
+ */
+typedef int Buffer;
 
-typedef long Buffer;
+#define InvalidBuffer	0
 
 /*
  * BufferIsInvalid
@@ -26,12 +31,6 @@ typedef long Buffer;
 #define BufferIsInvalid(buffer) ((buffer) == InvalidBuffer)
 
 /*
- * BufferIsUnknown
- *		True iff the buffer is unknown.
- */
-#define BufferIsUnknown(buffer) ((buffer) == UnknownBuffer)
-
-/*
  * BufferIsLocal
  *		True iff the buffer is local (not visible to other servers).
  */
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index d45c8888c1d..9d7f568e193 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: bufmgr.h,v 1.51 2001/05/12 19:58:28 tgl Exp $
+ * $Id: bufmgr.h,v 1.52 2001/06/09 18:16:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -75,10 +75,6 @@ extern long *LocalRefCount;
  *		True iff the given buffer number is valid (either as a shared
  *		or local buffer).
  *
- * Note:
- *		BufferIsValid(InvalidBuffer) is False.
- *		BufferIsValid(UnknownBuffer) is False.
- *
  * Note: For a long time this was defined the same as BufferIsPinned,
  * that is it would say False if you didn't hold a pin on the buffer.
  * I believe this was bogus and served only to mask logic errors.
@@ -158,8 +154,6 @@ extern long *LocalRefCount;
 /*
  * prototypes for functions in bufmgr.c
  */
-extern Buffer RelationGetBufferWithBuffer(Relation relation,
-							BlockNumber blockNumber, Buffer buffer);
 extern Buffer ReadBuffer(Relation reln, BlockNumber blockNum);
 extern int	WriteBuffer(Buffer buffer);
 extern int	WriteNoReleaseBuffer(Buffer buffer);