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AW: Re: Backup and Recovery

From: Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at>
To: "'ncm(at)zembu(dot)com'" <ncm(at)zembu(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: AW: Re: Backup and Recovery
Date: 2001-07-05 12:27:01
Message-ID: 11C1E6749A55D411A9670001FA687963368367@sdexcsrv1.f000.d0188.sd.spardat.at (view raw or flat)
Thread:
Lists: pgsql-hackers
> > Also, isn't the WAL format rather bulky to archive hours and hours of?

If it were actually too bulky, then it needs to be made less so, since that
directly affects overall performance :-) 

> > I would expect high-level transaction redo records to be much more compact;
> > mixed into the WAL, such records shouldn't make the WAL grow much faster.

All redo records have to be at the tuple level, so what higher-level are you talking 
about ? (statement level redo records would not be able to reproduce the same
resulting table data (keyword: transaction isolation level)) 

> The page images are not needed and can be thrown away once the page is
> completely sync'ed to disk or a checkpoint happens.

Actually they should at least be kept another few seconds to allow "stupid"
disks to actually write the pages :-) But see previous mail, they can also 
help with various BAR restore solutions.

Andreas

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