Re: NOLOGGING option, or ? - Mailing list pgsql-hackers

From Greg Stark
Subject Re: NOLOGGING option, or ?
Date
Msg-id 87acmav65o.fsf@stark.xeocode.com
Whole thread Raw
In response to Re: NOLOGGING option, or ?  (Neil Conway <neilc@samurai.com>)
Responses Re: NOLOGGING option, or ?
List pgsql-hackers
Neil Conway <neilc@samurai.com> writes:

> On Wed, 2005-06-01 at 00:40 -0400, Alvaro Herrera wrote:
> > This doesn't work for COPY, but maybe for CREATE TABLE AS we could log
> > the fact that the command was executed, so the replayer could execute
> > the same command again.
> > 
> > Of course, this handwaving doesn't explain how the system in recovery
> > mode would be able to execute a full query to reconstruct the table
> 
> There's also the typical problem with this kind of approach: how do you
> handle non-deterministic queries? (e.g. "CREATE TABLE ... AS SELECT
> random(), gettimeofday(), some_func(t1.x) FROM t1 LIMIT 5")

For CREATE TABLE AS in the non-PITR case you don't really need to WAL log the
records at all. If it fails in the middle you just drop the table. When it
completes you do a checkpoint before acknowledging the COMMIT.

I think this is already done for CREATE INDEX/REINDEX, also only in the
non-PITR case.

-- 
greg



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