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Re: pg_migrator progress

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Gregory Stark <stark(at)enterprisedb(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: pg_migrator progress
Date: 2009-02-18 15:47:25
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
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.

			regards, tom lane

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