Re: Reviewing freeze map code - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Reviewing freeze map code
Date
Msg-id CA+TgmoaR4_Yw=FCsBbgTn6n18d-d8sOonzvYDJMxmKt30yukmw@mail.gmail.com
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In response to Re: Reviewing freeze map code  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
On Thu, Jul 7, 2016 at 2:04 PM, Andres Freund <andres@anarazel.de> wrote:
>> Yeah, that's true, but I'm having a bit of trouble imagining exactly
>> we end up with corruption that actually matters.  I guess a torn page
>> could do it.
>
> I think Noah pointed out a bad scenario: If we crash after putting the
> xid in the page header, but before WAL logging, the xid could get reused
> after the crash. By a different transaction. And suddenly the row isn't
> visible anymore, after the reused xid commits...

Oh, wow.  Yikes.  OK, so I guess we should try to back-patch the fix, then.

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



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