When running WAL backups and warm-standby restores (we're currently on
PG 8.2), do the vacuumlo changes, vacuum, analyze and reindex type
commands get pushed through WAL files to the backup? Or will the backup
database not have these maintenance items done?

Thanks,
David

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On Tue, 2008-01-15 at 09:19 -0800, David Wall wrote:

> When running WAL backups and warm-standby restores (we're currently on
> PG 8.2), do the vacuumlo changes, vacuum, analyze and reindex type
> commands get pushed through WAL files to the backup? Or will the backup
> database not have these maintenance items done?

All of those commands produce WAL for critical changes to data blocks,
so those are passed through correctly.

Hint bits are not set following recovery, so a full database VACUUM may
help later performance, depends upon your access patterns. It's probably
good for peace of mind too, but it's a long way from being an essential
requirement.

--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com


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Simon Riggs <simon@2ndquadrant.com> writes:
> All of those commands produce WAL for critical changes to data blocks,
> so those are passed through correctly.

> Hint bits are not set following recovery, so a full database VACUUM may
> help later performance, depends upon your access patterns.

That's only partially true. Full-page images in WAL will propagate hint
bits, so in practice you could expect that only about one checkpoint
cycle's worth of hint information is missing. If you'd been running
with full_page_writes = off then this doesn't hold, and in that case
I'd agree that a forced vacuum might be worth the trouble.

regards, tom lane

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