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Arrange to recycle old XLOG log segment files as new segment files,

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rather than deleting them only to have to create more.  Steady state
is 2*CHECKPOINT_SEGMENTS + WAL_FILES + 1 segment files, which will
simply be renamed rather than constantly deleted and recreated.
To make this safe, added current XLOG file/offset number to page
header of XLOG pages, so that an un-overwritten page from an old
incarnation of a logfile can be reliably told from a valid page.
This change means that if you try to restart postmaster in a CVS-tip
database after installing the change, you'll get a complaint about
bad XLOG page magic number.  If you don't want to initdb, run
contrib/pg_resetxlog (and be sure you shut down the old postmaster
cleanly).
This commit is contained in:
Tom Lane
2001-07-19 02:12:35 +00:00
parent 8b77efdded
commit 7d4d5c00f0
3 changed files with 209 additions and 84 deletions
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6
contrib/pg_resetxlog/pg_resetxlog.c
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@@ -23,7 +23,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Header: /cvsroot/pgsql/contrib/pg_resetxlog/Attic/pg_resetxlog.c,v 1.5 2001/06/06 17:07:38 tgl Exp $
* $Header: /cvsroot/pgsql/contrib/pg_resetxlog/Attic/pg_resetxlog.c,v 1.6 2001/07/19 02:12:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -857,6 +857,10 @@ WriteEmptyXLOG(void)
page->xlp_magic = XLOG_PAGE_MAGIC;
page->xlp_info = 0;
page->xlp_sui = ControlFile.checkPointCopy.ThisStartUpID;
page->xlp_pageaddr.xlogid =
ControlFile.checkPointCopy.redo.xlogid;
page->xlp_pageaddr.xrecoff =
ControlFile.checkPointCopy.redo.xrecoff - SizeOfXLogPHD;
record = (XLogRecord *) ((char *) page + SizeOfXLogPHD);
record->xl_prev.xlogid = 0;
record->xl_prev.xrecoff = 0;