From: | Noah Misch <noah(at)leadboat(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-committers(at)postgresql(dot)org |
Subject: | Re: pgsql: Avoid corrupting tables when ANALYZE inside a transaction is rol |
Date: | 2014-10-30 04:09:36 |
Message-ID: | 20141030040936.GA407655@tornado.leadboat.com |
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Lists: | pgsql-committers |
On Wed, Oct 29, 2014 at 10:12:44PM +0000, Tom Lane wrote:
> Avoid corrupting tables when ANALYZE inside a transaction is rolled back.
>
> VACUUM and ANALYZE update the target table's pg_class row in-place, that is
> nontransactionally. This is OK, more or less, for the statistical columns,
> which are mostly nontransactional anyhow. It's not so OK for the DDL hint
> flags (relhasindex etc), which might get changed in response to
> transactional changes that could still be rolled back. This isn't a
> problem for VACUUM, since it can't be run inside a transaction block nor
> in parallel with DDL on the table. However, we allow ANALYZE inside a
> transaction block, so if the transaction had earlier removed the last
> index, rule, or trigger from the table, and then we roll back the
> transaction after ANALYZE, the table would be left in a corrupted state
> with the hint flags not set though they should be.
>
> To fix, suppress the hint-flag updates if we are InTransactionBlock().
Shouldn't this use IsInTransactionChain(), to catch the other ways ANALYZE can
share a transaction with DDL?
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