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Fix is-it-time-for-a-checkpoint logic so that checkpoint_segments can

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usefully be larger than 255.  Per gripe from Simon Riggs.
This commit is contained in:
Tom Lane 2004-12-17 00:10:36 +00:00
parent 24658a2d53
commit ff5a354ece
1 changed files with 26 additions and 9 deletions
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35
src/backend/access/transam/xlog.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group * Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.178 2004/11/17 16:26:59 tgl Exp $ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.179 2004/12/17 00:10:36 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -1201,21 +1201,38 @@ XLogWrite(XLogwrtRqst WriteRqst)
UpdateControlFile(); UpdateControlFile();
/* /*
* Signal postmaster to start a checkpoint if it's been * Signal bgwriter to start a checkpoint if it's been
* too long since the last one. (We look at local copy of * too long since the last one. (We look at local copy of
* RedoRecPtr which might be a little out of date, but * RedoRecPtr which might be a little out of date, but
* should be close enough for this purpose.) * should be close enough for this purpose.)
*
* A straight computation of segment number could overflow
* 32 bits. Rather than assuming we have working 64-bit
* arithmetic, we compare the highest-order bits separately,
* and force a checkpoint immediately when they change.
*/ */
if (IsUnderPostmaster && if (IsUnderPostmaster)
(openLogId != RedoRecPtr.xlogid ||
openLogSeg >= (RedoRecPtr.xrecoff / XLogSegSize) +
(uint32) CheckPointSegments))
{ {
uint32 old_segno,
new_segno;
uint32 old_highbits,
new_highbits;
old_segno = (RedoRecPtr.xlogid % XLogSegSize) * XLogSegsPerFile +
(RedoRecPtr.xrecoff / XLogSegSize);
old_highbits = RedoRecPtr.xlogid / XLogSegSize;
new_segno = (openLogId % XLogSegSize) * XLogSegsPerFile +
openLogSeg;
new_highbits = openLogId / XLogSegSize;
if (new_highbits != old_highbits ||
new_segno >= old_segno + (uint32) CheckPointSegments)
{
#ifdef WAL_DEBUG #ifdef WAL_DEBUG
if (XLOG_DEBUG) if (XLOG_DEBUG)
elog(LOG, "time for a checkpoint, signaling bgwriter"); elog(LOG, "time for a checkpoint, signaling bgwriter");
#endif #endif
RequestCheckpoint(false); RequestCheckpoint(false);
}
} }
} }
LWLockRelease(ControlFileLock); LWLockRelease(ControlFileLock);