Re: GetTransactionSnapshot() in enum.c

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andres Freund <andres(at)2ndquadrant(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: GetTransactionSnapshot() in enum.c
Date: 2013-08-28 17:24:52
Message-ID: CA+Tgmobzt30UE6uM4bO4=A-R9yJwW8tj7QiSwPEKVoLhquTn9Q@mail.gmail.com
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On Mon, Aug 26, 2013 at 4:31 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Mon, Aug 19, 2013 at 1:41 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> BTW, I notice that the MVCC-catalog-scans patch summarily asserts that
>>> RenumberEnumType no longer poses any concurrency hazards. I doubt that's
>>> true: isn't it still possible that pg_enum rows acquired through the
>>> syscaches will have inconsistent enumsortorder values, if they were
>>> read at different times? If you want to examine enumsortorder, you really
>>> need to be comparing rows you know were read with the *same* snapshot.
>
>> Good point, I missed that. Here's a proposed comment patch.
>
> Looks sane to me.

Thanks for the review. Committed.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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