database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-10-27 00:12:01 +03:00
Code Activity

Make large sequential scans and VACUUMs work in a limited-size "ring" of

Browse Source 
buffers, rather than blowing out the whole shared-buffer arena.  Aside from
avoiding cache spoliation, this fixes the problem that VACUUM formerly tended
to cause a WAL flush for every page it modified, because we had it hacked to
use only a single buffer.  Those flushes will now occur only once per
ring-ful.  The exact ring size, and the threshold for seqscans to switch into
the ring usage pattern, remain under debate; but the infrastructure seems
done.  The key bit of infrastructure is a new optional BufferAccessStrategy
object that can be passed to ReadBuffer operations; this replaces the former
StrategyHintVacuum API.

This patch also changes the buffer usage-count methodology a bit: we now
advance usage_count when first pinning a buffer, rather than when last
unpinning it.  To preserve the behavior that a buffer's lifetime starts to
decrease when it's released, the clock sweep code is modified to not decrement
usage_count of pinned buffers.

Work not done in this commit: teach GiST and GIN indexes to use the vacuum
BufferAccessStrategy for vacuum-driven fetches.

Original patch by Simon, reworked by Heikki and again by Tom.
This commit is contained in:
Tom Lane
2007-05-30 20:12:03 +00:00
parent 0a6f2ee84d
commit d526575f89
24 changed files with 722 additions and 262 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
src/include/access/genam.h
View File

@@ -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/genam.h,v 1.66 2007/01/05 22:19:50 momjian Exp $
* $PostgreSQL: pgsql/src/include/access/genam.h,v 1.67 2007/05/30 20:12:02 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -40,6 +40,7 @@ typedef struct IndexVacuumInfo
bool vacuum_full; /* VACUUM FULL (we have exclusive lock) */
int message_level; /* ereport level for progress messages */
double num_heap_tuples; /* tuples remaining in heap */
BufferAccessStrategy strategy; /* access strategy for reads */
} IndexVacuumInfo;
/*

11
src/include/access/hash.h
View File

@@ -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/hash.h,v 1.80 2007/05/03 16:45:58 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/hash.h,v 1.81 2007/05/30 20:12:02 tgl Exp $
*
* NOTES
* modeled after Margo Seltzer's hash implementation for unix.
@@ -273,11 +273,13 @@ extern void _hash_doinsert(Relation rel, IndexTuple itup);
/* hashovfl.c */
extern Buffer _hash_addovflpage(Relation rel, Buffer metabuf, Buffer buf);
extern BlockNumber _hash_freeovflpage(Relation rel, Buffer ovflbuf);
extern BlockNumber _hash_freeovflpage(Relation rel, Buffer ovflbuf,
BufferAccessStrategy bstrategy);
extern void _hash_initbitmap(Relation rel, HashMetaPage metap,
BlockNumber blkno);
extern void _hash_squeezebucket(Relation rel,
Bucket bucket, BlockNumber bucket_blkno);
Bucket bucket, BlockNumber bucket_blkno,
BufferAccessStrategy bstrategy);
/* hashpage.c */
extern void _hash_getlock(Relation rel, BlockNumber whichlock, int access);
@@ -287,6 +289,9 @@ extern Buffer _hash_getbuf(Relation rel, BlockNumber blkno,
int access, int flags);
extern Buffer _hash_getinitbuf(Relation rel, BlockNumber blkno);
extern Buffer _hash_getnewbuf(Relation rel, BlockNumber blkno);
extern Buffer _hash_getbuf_with_strategy(Relation rel, BlockNumber blkno,
int access, int flags,
BufferAccessStrategy bstrategy);
extern void _hash_relbuf(Relation rel, Buffer buf);
extern void _hash_dropbuf(Relation rel, Buffer buf);
extern void _hash_wrtbuf(Relation rel, Buffer buf);

3
src/include/access/relscan.h
View File

@@ -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 1.53 2007/05/27 03:50:39 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.54 2007/05/30 20:12:02 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -27,6 +27,7 @@ typedef struct HeapScanDescData
int rs_nkeys; /* number of scan keys */
ScanKey rs_key; /* array of scan key descriptors */
BlockNumber rs_nblocks; /* number of blocks to scan */
BufferAccessStrategy rs_strategy; /* access strategy for reads */
bool rs_pageatatime; /* verify visibility page-at-a-time? */
/* scan current state */

3
src/include/access/xlog.h
View File

@@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.77 2007/05/20 21:08:19 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.78 2007/05/30 20:12:02 tgl Exp $
*/
#ifndef XLOG_H
#define XLOG_H
@@ -159,6 +159,7 @@ extern bool XLOG_DEBUG;
extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata);
extern void XLogFlush(XLogRecPtr RecPtr);
extern bool XLogNeedsFlush(XLogRecPtr RecPtr);
extern void xlog_redo(XLogRecPtr lsn, XLogRecord *record);
extern void xlog_desc(StringInfo buf, uint8 xl_info, char *rec);