From: | Gavin Sherry <swm(at)linuxworld(dot)com(dot)au> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Teodor Sigaev <teodor(at)sigaev(dot)ru>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: VACUUM/t_ctid bug (was Re: GiST concurrency commited) |
Date: | 2005-08-23 06:06:54 |
Message-ID: | Pine.LNX.4.58.0508231604160.30102@linuxworld.com.au |
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Lists: | pgsql-hackers |
On Sat, 20 Aug 2005, Tom Lane wrote:
> Gavin Sherry <swm(at)linuxworld(dot)com(dot)au> writes:
> > I've written some quick scripts. One just vacuums constantly (999 vacuums
> > to 1 vacuum full) while three other scripts three randomly insert
> > into, update and delete from 3 tables. There's a mix of small and large
> > transactions. The tables have a single int column. It is set up to run 3
> > million transactions across the 3 scripts.
>
> Note that since the issues have mainly to do with update chains, it'd be
> good to stress cases where a row is updated multiple times before being
> deleted. And use at least one long-running transaction, so that VACUUM
> can't just throw away the update chain.
Right.
I modified the test so have multiple updates of a given row mixed with
concurrent long running read transactions. Vacuum was running repeatedly
in a concurrent session. I did not encounter any problems.
However, the results are inconclusive since I ran the same test against
HEAD from 10 days ago and didn't manage to trigger the problem Teodor's
script did. I'll take a better look tomorrow.
Gavin
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