Horton

Re: StandbyRecoverPreparedTransactions recovers subtrans links incorrectly

Simon Riggs <simon@2ndquadrant.com>

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From: Simon Riggs <simon@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2017-04-23T17:41:41Z
Lists: pgsql-hackers 
On 23 April 2017 at 17:17, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Simon Riggs <simon@2ndquadrant.com> writes:
>>> Also, when I fix that, it gets further but still crashes at the same
>>> Assert in SubTransSetParent.  The proximate cause this time seems to be
>>> that RecoverPreparedTransactions's calculation of overwriteOK is wrong:
>>> it's computing that as "false", but in reality the subtrans link in
>>> question has already been set.
>
>> Not sure about that, investigating.
>
> As a quick hack, I just hotwired RecoverPreparedTransactions to set
> overwriteOK = true always, and with that and the SubTransSetParent
> argument-order fix, HEAD passes the recovery tests.  Maybe we can
> be smarter than that, but this might be a good short-term fix to get
> the buildfarm green again.

That would work. I've been looking into a fix I can explain, but "do
it always" may actually be it.

OK, I'll do that.

-- 
Simon Riggs                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Rework handling of subtransactions in 2PC recovery

  2. Fix order of arguments to SubTransSetParent().

  3. Speedup 2PC recovery by skipping two phase state files in normal path