Re: Regarding Checkpoint Redo Record

On Wed, Jan 4, 2012 at 4:06 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> But, the OP makes me wonder: why can a standby only perform a
>> restartpoint where the master performed a checkpoint?  It seems like a
>> standby ought to be able to create a restartpoint anywhere, just by
>> writing everything, flushing it to disk, and update pg_control.
>
> Perhaps, but then crash restarts would have to accept start pointers
> that point at any random place in the WAL.  I like the additional error
> checking of verifying that there's a checkpoint recod there.

I could go either way on that one, but...

> Also
> I think the full-page-write mechanism would no longer protect against
> torn pages during replay if you did that.

...this is a very good point.

--
Robert Haas
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