Re: Online base backup from the hot-standby

> > I can't see a reason why we would use a new WAL record for this,
> > rather than modify the XLOG_PARAMETER_CHANGE record type which was
> > created for a very similar reason.
> > The code would be much simpler if we just extend
> > XLOG_PARAMETER_CHANGE, so please can we do that?
>
> Sure.
>
> > The log message "full_page_writes on master is set invalid more than
> > once during online backup" should read "at least once" rather than
> > "more than once".
>
> Yes.
>
> > lastFpwDisabledLSN needs to be initialized.
>
> I think it don't need because all values in XLogCtl is initialized 0.
>
> > Is there a reason to add lastFpwDisabledLSN onto the Control file? If
> > we log parameters after every checkpoint then we'll know the values
> > when we startup. If we keep logging parameters this way we'll end up
> > with a very awkward and large control file. I would personally prefer
> > to avoid that, but that thought could go either way. Let's see if
> > anyone else thinks that also.
>
> Yes. I add to CreateCheckPoint().
>
> Image:
> CreateCheckPoint()
> {
> if (!shutdown && XLogStandbyInfoActive())
> {
> LogStandbySnapshot()
> XLogReportParameters()
> }
> }
>
> XLogReportParameters()
> {
> if (fpw == 'off' || ... )
> XLOGINSERT()
> }
>
> However, it'll write XLOG_PARAMETER_CHANGE every checkpoints when FPW is 'off'.
> (It will increases the amount of WAL.)
> Is it OK?

Done.

Updated patch attached.

Regards.

--------------------------------------------
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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