Re: Proposing pg_hibernate

On Wed, Jun 4, 2014 at 2:50 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> The thing I was concerned about is that the system might have been in
> recovery for months. What was hot at the time the base backup was
> taken seems like a poor guide to what will be hot at the time of
> promotion. Consider a history table, for example: the pages at the
> end, which have just been written, are much more likely to be useful
> than anything earlier.

I think you are specifically talking about a warm-standby that runs
recovery for months before being brought online. As described in my
response to Amit, if the base backup used to create that standby was
taken after the BlockReaders had restored the buffers (which should
complete within few minutes of startup, even for large databases),
then there's no concern since the base backup wouldn't contain the
save-files.

If it's a hot-standby, the restore process would start as soon as the
database starts accepting connections, finish soon after, and get
completely out of the way of the normal recovery process. At which
point the buffers populated by the recovery would compete only with
the buffers being requested by backends, which is the normal
behaviour.

Best regards,
--
Gurjeet Singh http://gurjeet.singh.im/

EDB www.EnterpriseDB.com