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: Vacuum only with 20% old tuples
Date: 2000-07-26 15:09:17
Message-ID: 11C1E6749A55D411A9670001FA68796336802F@sdexcsrv1.f000.d0188.sd.spardat.at
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> Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> writes:
> >> We scan the log and come upon the rename.
> >> Hmm, there's a file foo and no file bar ... looks like the
> >> rename didn't get done, so do it. Ooops.
>
> > No again. You come upon "starting rename operation" and then either
> > no more log records (backend abort)
> > or
> > log record "rename succeeded"
> > or
> > log record "rename failed" --> transaction abort
>
> > In this scenario you can decide what to do without second guessing.
>
> 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.
The backends could not have created a new file of the old name
after "starting rename" beeing last log record.

Andreas

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