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Remove RelationGetBufferWithBuffer(), which is horribly confused about

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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.
This commit is contained in:
Tom Lane
2001-06-09 18:16:59 +00:00
parent 3247989130
commit bdadc9bf1c
9 changed files with 138 additions and 551 deletions
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39
src/include/access/relscan.h
View File

@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: relscan.h,v 1.20 2001/01/24 19:43:19 momjian Exp $
* $Id: relscan.h,v 1.21 2001/06/09 18:16:59 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -16,25 +16,16 @@
#include "utils/tqual.h"
typedef ItemPointerData MarkData;
typedef struct HeapScanDescData
{
Relation rs_rd; /* pointer to relation descriptor */
HeapTupleData rs_ptup; /* previous tuple in scan */
HeapTupleData rs_ctup; /* current tuple in scan */
HeapTupleData rs_ntup; /* next tuple in scan */
Buffer rs_pbuf; /* previous buffer in scan */
Buffer rs_cbuf; /* current buffer in scan */
Buffer rs_nbuf; /* next buffer in scan */
ItemPointerData rs_mptid; /* marked previous tid */
ItemPointerData rs_mctid; /* marked current tid */
ItemPointerData rs_mntid; /* marked next tid */
ItemPointerData rs_mcd; /* marked current delta XXX ??? */
HeapTupleData rs_ctup; /* current tuple in scan, if any */
Buffer rs_cbuf; /* current buffer in scan, if any */
/* NB: if rs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
ItemPointerData rs_mctid; /* marked tid, if any */
Snapshot rs_snapshot; /* snapshot to see */
bool rs_atend; /* restart scan at end? */
uint16 rs_cdelta; /* current delta in chain */
uint16 rs_nkeys; /* number of attributes in keys */
uint16 rs_nkeys; /* number of scan keys to select tuples */
ScanKey rs_key; /* key descriptors */
} HeapScanDescData;
@@ -43,22 +34,24 @@ typedef HeapScanDescData *HeapScanDesc;
typedef struct IndexScanDescData
{
Relation relation; /* relation descriptor */
void *opaque; /* am-specific slot */
ItemPointerData previousItemData; /* previous index pointer */
void *opaque; /* access-method-specific info */
ItemPointerData currentItemData; /* current index pointer */
ItemPointerData nextItemData; /* next index pointer */
MarkData previousMarkData; /* marked previous pointer */
MarkData currentMarkData;/* marked current pointer */
MarkData nextMarkData; /* marked next pointer */
ItemPointerData currentMarkData; /* marked current pointer */
uint8 flags; /* scan position flags */
bool scanFromEnd; /* restart scan at end? */
uint16 numberOfKeys; /* number of key attributes */
ScanKey keyData; /* key descriptor */
uint16 numberOfKeys; /* number of scan keys to select tuples */
ScanKey keyData; /* key descriptors */
FmgrInfo fn_getnext; /* cached lookup info for am's getnext fn */
} IndexScanDescData;
typedef IndexScanDescData *IndexScanDesc;
/* IndexScanDesc flag bits (none of these are actually used currently) */
#define ScanUnmarked 0x01
#define ScanUncheckedPrevious 0x02
#define ScanUncheckedNext 0x04
/* ----------------
* IndexScanDescPtr is used in the executor where we have to
* keep track of several index scans when using several indices

9
src/include/access/skey.h
View File

@@ -7,8 +7,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: skey.h,v 1.15 2001/06/01 02:41:36 tgl Exp $
*
* $Id: skey.h,v 1.16 2001/06/09 18:16:59 tgl Exp $
*
* Note:
* Needs more accessor/assignment routines.
@@ -20,6 +19,7 @@
#include "access/attnum.h"
#include "fmgr.h"
typedef struct ScanKeyData
{
bits16 sk_flags; /* flags */
@@ -38,11 +38,6 @@ typedef ScanKeyData *ScanKey;
#define SK_COMMUTE 0x8 /* commute function (not fully supported) */
#define ScanUnmarked 0x01
#define ScanUncheckedPrevious 0x02
#define ScanUncheckedNext 0x04
/*
* prototypes for functions in access/common/scankey.c
*/