From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
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To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Move tablespace |
Date: | 2010-04-21 11:37:57 |
Message-ID: | 4BCEE395.4090000@enterprisedb.com |
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Lists: | pgsql-hackers |
Simon Riggs wrote:
> On Tue, 2010-04-20 at 21:03 -0400, Tom Lane wrote:
>> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>>> Following patch writes a new WAL record that just says "copy foo to
>>> newts" and during replay we flush buffers and then re-execute the copy
>>> (but only when InArchiveRecovery). So the copy happens locally on the
>>> standby, not copying from primary to standby. We do this just with a
>>> little refactoring and a simple new WAL message.
>> And what happens to crash-recovery replay? You can't have it both ways,
>> either the data is in WAL or it's missing.
>
> The patch changes nothing in the case of crash recovery.
What happens if the record is replayed twice in archive recovery? For
example if you stop and restart a standby server after it has replayed
that record. What does the 2nd redo attempt do if the source file was
already deleted by the 1st recovery.
I also think we shouldn't be fiddling with this at this stage in the
release cycle.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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