| From: | Martin Devera <devik(at)cdi(dot)cz> |
|---|---|
| To: | "Mikheev, Vadim" <vmikheev(at)SECTORBASE(dot)COM> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | RE: WAL & SHM principles |
| Date: | 2001-03-09 15:03:39 |
| Message-ID: | Pine.LNX.4.10.10103091555420.12401-100000@luxik.cdi.cz |
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| Lists: | pgsql-hackers |
> > Pros: upper layers can think thet buffers are always safe/logged and
> > there is no special handling for indices; very simple/fast redo
> > Cons: can't implement undo - but in non-overwriting is not needed (?)
>
> But needed if we want to get rid of vacuum and have savepoints.
Hmm. How do you implement savepoints ? When there is rollback to savepoint
do you use xlog to undo all changes which the particular transaction has
done ? Hmmm it seems nice ... these resords are locked by such transaction
so that it can safely undo them :-)
Am I right ?
But how can you use xlog to get rid of vacuum ? Do you treat all delete
log records as candidates for free space ?
regards, devik
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