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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2007-05-02 23:18:03 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2007-05-02 23:18:03 +0000 |
| commit | 8c3cc86e7b688b0efe5ec6ce4f4342c2883b1db5 (patch) | |
| tree | 33cfc93810e9c15988c7dc26f7350a6b9d5d4c53 /src/backend/access/transam/xlogutils.c | |
| parent | 8ec943856a4e94637600fa7cad976281ca3f4071 (diff) | |
| download | postgresql-8c3cc86e7b688b0efe5ec6ce4f4342c2883b1db5.tar.gz postgresql-8c3cc86e7b688b0efe5ec6ce4f4342c2883b1db5.zip | |
During WAL recovery, when reading a page that we intend to overwrite completely
from the WAL data, don't bother to physically read it; just have bufmgr.c
return a zeroed-out buffer instead. This speeds recovery significantly,
and also avoids unnecessary failures when a page-to-be-overwritten has corrupt
page headers on disk. This replaces a former kluge that accomplished the
latter by pretending zero_damaged_pages was always ON during WAL recovery;
which was OK when the kluge was put in, but is unsafe when restoring a WAL
log that was written with full_page_writes off.
Heikki Linnakangas
Diffstat (limited to 'src/backend/access/transam/xlogutils.c')
| -rw-r--r-- | src/backend/access/transam/xlogutils.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c index a433ad9fca7..39c3269bc11 100644 --- a/src/backend/access/transam/xlogutils.c +++ b/src/backend/access/transam/xlogutils.c @@ -11,7 +11,7 @@ * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/backend/access/transam/xlogutils.c,v 1.49 2007/01/05 22:19:24 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/xlogutils.c,v 1.50 2007/05/02 23:18:03 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -206,7 +206,9 @@ XLogCheckInvalidPages(void) * If "init" is true then the caller intends to rewrite the page fully * using the info in the XLOG record. In this case we will extend the * relation if needed to make the page exist, and we will not complain about - * the page being "new" (all zeroes). + * the page being "new" (all zeroes); in fact, we usually will supply a + * zeroed buffer without reading the page at all, so as to avoid unnecessary + * failure if the page is present on disk but has corrupt headers. * * If "init" is false then the caller needs the page to be valid already. * If the page doesn't exist or contains zeroes, we return InvalidBuffer. @@ -226,7 +228,10 @@ XLogReadBuffer(Relation reln, BlockNumber blkno, bool init) if (blkno < lastblock) { /* page exists in file */ - buffer = ReadBuffer(reln, blkno); + if (init) + buffer = ReadOrZeroBuffer(reln, blkno); + else + buffer = ReadBuffer(reln, blkno); } else { |