From: | Jun Ishiduka <ishizuka(dot)jun(at)po(dot)ntts(dot)co(dot)jp> |
---|---|
To: | masao(dot)fujii(at)gmail(dot)com |
Cc: | ssinger_pg(at)sympatico(dot)ca, simon(at)2ndquadrant(dot)com, pgsql-hackers(at)postgresql(dot)org, magnus(at)hagander(dot)net, robertmhaas(at)gmail(dot)com, cedric(dot)villemain(dot)debian(at)gmail(dot)com, heikki(dot)linnakangas(at)enterprisedb(dot)com |
Subject: | Re: Online base backup from the hot-standby |
Date: | 2011-10-13 04:31:27 |
Message-ID: | 201110130432.p9D4WjtJ026390@ccmds32.silk.ntts.co.jp |
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Thread: | |
Lists: | pgsql-hackers |
> > > 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
Okay, I changes the patch to this messages.
If someone says there is a idea better than it, I will consider again.
> > 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.
Sure.
> 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.
YES.
> 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?
Yes, It is possible.
> In do_pg_start_backup() and do_pg_stop_backup(), the spinlock must be held to
> see XLogCtl->lastFpwDisabledLSN.
Yes.
> What about changing the error message to:
> ERROR: WAL generated with full_page_writes=off was replayed during online backup
Okay, too.
--------------------------------------------
Jun Ishizuka
NTT Software Corporation
TEL:045-317-7018
E-Mail: ishizuka(dot)jun(at)po(dot)ntts(dot)co(dot)jp
--------------------------------------------
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