2011/10/12 Jun Ishiduka <ishizuka....@po.ntts.co.jp>:
> > ERROR: full_page_writes on master is set invalid at least once since
> > latest checkpoint
> >
> > I think this error should be rewritten as
> > ERROR: full_page_writes on master has been off at some point since
> > latest checkpoint
> >
> > We should be using 'off' instead of 'invalid' since that is what is what
> > the user sets it to.
>
> Sure.
What about the following message? It sounds more precise to me.
ERROR: WAL generated with full_page_writes=off was replayed since last
restartpoint
> I updated to patch corresponded above-comments.
Thanks for updating the patch! Here are the comments:
* don't yet have the insert lock, forcePageWrites could change under
us,
* but we'll recheck it once we have the lock.
*/
- doPageWrites = fullPageWrites || Insert->forcePageWrites;
+ doPageWrites = Insert->fullPageWrites || Insert->forcePageWrites;
The source comment needs to be modified.
* just turned off, we could recompute the record without full pages,
but
* we choose not to bother.)
*/
- if (Insert->forcePageWrites && !doPageWrites)
+ if ((Insert->fullPageWrites || Insert->forcePageWrites) &&
!doPageWrites)
Same as above.
+ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE);
+ XLogCtl->Insert.fullPageWrites = fullPageWrites;
+ LWLockRelease(WALInsertLock);
I don't think WALInsertLock needs to be hold here because there is no
concurrently running process which can access Insert.fullPageWrites.
For example, Insert->currpos and Insert->LogwrtResult are also changed
without the lock there.
The source comment of XLogReportParameters() needs to be modified.
XLogReportParameters() should skip writing WAL if full_page_writes has not been
changed by SIGHUP.
XLogReportParameters() should skip updating pg_control if any parameter related
to hot standby has not been changed.
+ if (!fpw_manager)
+ {
+ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE);
+ fpw = XLogCtl->Insert.fullPageWrites;
+ LWLockRelease(WALInsertLock);
It's safe to take WALInsertLock with shared mode here.
In checkpoint, XLogReportParameters() is called only when wal_level is
hot_standby.
OTOH, in walwriter, it's always called even when wal_level is not hot_standby.
Can't we skip calling XLogReportParameters() whenever wal_level is not
hot_standby?
In do_pg_start_backup() and do_pg_stop_backup(), the spinlock must be held to
see XLogCtl->lastFpwDisabledLSN.
+ /* check whether the master's FPW is 'off' since pg_start_backup. */
+ if (recovery_in_progress && XLByteLE(startpoint,
XLogCtl->lastFpwDisabledLSN))
+ ereport(ERROR,
+
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("full_page_writes on master has been off at
some point
during online backup")));
What about changing the error message to:
ERROR: WAL generated with full_page_writes=off was replayed during online backup
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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