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AW: AW: AW: AW: Vacuum only with 20% old tuples

From: Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at>
To: "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "'Hiroshi Inoue'" <Inoue(at)tpf(dot)co(dot)jp>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: AW: AW: AW: AW: Vacuum only with 20% old tuples
Date: 2000-07-27 08:09:29
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
> Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> writes:
> >> If there are no more records, then you are reduced to 
> guessing whether
> >> you have to undo the rename or not.  If you guess wrong, 
> you leave the
> >> database in a corrupted state.
> > If the original filename exists the rename failed else it succeeded.
> That's exactly the unreliable assumption I do not want to make.
> > The backends could not have created a new file of the old name
> > after "starting rename" beeing last log record. 
> So you're assuming that we fsync() the log after *each* item is added?
> *Within* a transaction?  fsync only at end of xact was the plan,
> I believe.

With trx log we imho would not need any fsyncs anymore
(except maybe checkpoints).
We would open the trxlog file with O_SYNC and only do a write
when it is absolutely necessary (buffer overflow, end of trx).
But yes the rename log entries (only those) would need to be 
written immediately. Is this a performance issue? I guess not.



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Subject: AW: TOAST & vacuum
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