Re: pg_migrator progress

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Gregory Stark <stark(at)enterprisedb(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: pg_migrator progress
Date: 2009-03-28 01:55:49
Message-ID: 200903280155.n2S1tnq04102@momjian.us
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Tom Lane wrote:
> Gregory Stark <stark(at)enterprisedb(dot)com> writes:
> > Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> >> No, but this would just be the same situation that prevails after
> >> OID-counter wraparound, so I don't see a compelling need for us to
> >> change the OID counter in the new DB. If the user has done the Proper
> >> Things (ie, made unique indexes on his OIDs) then it won't matter.
> >> If he didn't, his old DB was a time bomb anyway.
>
> > Also I wonder about the performance of skipping over thousands or even
> > millions of OIDs for something like a toast table.
>
> I think that argument is a red herring. In the first place, it's
> unlikely that there'd be a huge run of consecutive OIDs *in the same
> table*. In the second place, if he does have such runs, the claim that
> he can't possibly have dealt with OID wraparound before seems pretty
> untenable --- he's obviously been eating lots of OIDs.
>
> But having said that, there isn't any real harm in fixing the OID
> counter to match what it was. You need to run pg_resetxlog to set the
> WAL position and XID counter anyway, and it can set the OID counter too.

FYI, I decided against restoring the oid counter because it might
collide with an oid assigned during pg_migrator schema creation.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

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