[pgpool-general: 934] Re: some questions about online recovery

[Kent Tong]

Thanks for the good explanation. So, pg_switch_xlog will generate the last
WAL file for use, but the second stage script in the example doesn't copy
any WAL file (in pg_xlog). Or will pg_switch_xlog also archive the WAL
files just like pg_stop_backup does?

On Thu, Aug 30, 2012 at 10:51 AM, Lazáro Rubén García Martínez <
lgarciam at vnz.uci.cu> wrote:

> In the first stage of online recovery you copy your data directory from
> primary node to detached node. In this stage, the primary server receives
> requests from users, then in the second stage of online recovery, the
> conections from clients need to waits until this stage ending. But, because
> in the first stage the primary server recive requests while you were copied
> your data directory to another node, in the shared buffers and wal buffers
> could by dirty blocks and is necesary to synchronize this dirty blocks to
> disk and generate a new wal segment that stablish the end of recovery
> process, this is the last wal to recovery.
>
> This is the perpose of forcing a log switch.
>
> Sorry for my bad english.
>
> Regards.
> ________________________________________
> From: pgpool-general-bounces at pgpool.net [pgpool-general-bounces at pgpool.net]
> On Behalf Of Kent Tong [kent.tong.mo at gmail.com]
> Sent: Wednesday, August 29, 2012 8:34 PM
> To: Tatsuo Ishii
> Cc: pgpool-general at pgpool.net
> Subject: [pgpool-general: 931] Re: some questions about online recovery
>
> On Thu, Aug 30, 2012 at 6:49 AM, Tatsuo Ishii <ishii at postgresql.org
> <mailto:ishii at postgresql.org>> wrote:
> That's a duty of archive command.
>
> Fair enough. So, that example assumes that the postgreSQL WAL archive
> (where the archive_command copies to) is accessible by all the nodes?
>
> pgpool_switch_xlog does more than pg_switch_xlog. It waits for log
> switching completion by looking at $archdir.
>
> Yes, I know. But what is the purpose of forcing a log switch?
>
> Thanks!
>
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> Fin a la injusticia, LIBERTAD AHORA A NUESTROS CINCO COMPATRIOTAS QUE SE
> ENCUENTRAN INJUSTAMENTE EN PRISIONES DE LOS EEUU!
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>



-- 
Kent Tong
IT author and consultant, child educator
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