WAL is the journal for postgres, so every event that happens goes into the WAL. Using it for backup or replication
simplyuses it to replay all events on the backup / replicated database.
----- Original Message ----
> From: Dmitry Melekhov <dm@belkam.com>
> To: Simon Riggs <simon@2ndquadrant.com>
> Cc: pgsql-general@postgresql.org
> Sent: Tuesday, 8 July, 2008 9:54:57 AM
> Subject: Re: [GENERAL] please explain vacuum with WAL
>
> Simon Riggs пишет:
> > On Tue, 2008-07-08 at 13:09 +0500, Dmitry Melekhov wrote:
> >
> >> Hello!
> >>
> >> I tried to ask this question in novice list.
> >> Just because there are no replies I try here.
> >> This is really novice question- I'm oracle dba :-)
> >>
> >>
> >>> I just installed 8.3 with WAL enabled.
> >>> But I can't understand why postgres generated many archive logs during
> >>> vacuum, if WAL is enabled.
> >>> Could you explain?
> >>>
> >
> > What do you mean "WAL is enabled"? That's not a term I recognize since
> > WAL is always enabled.
> >
> >
> AFAIK, it can be disabled. May be I'm wrong...
> > Best read this
> > http://developer.postgresql.org/pgdocs/postgres/routine-vacuuming.html
> >
> > VACUUM needs to perform writes to clear up, which generates WAL.
> >
> >
> This is what I don't understand.
> I think WAL can be used for point-in-time recovery.
> So, if I have database backup and WAL generated after this backup, I can
> do recovery, this mean WAL already contains all changes to database,
> without vacuum. Could you tell me what is wrong in my sentence?
>
>
>
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