> On 20 Mar 2017, at 16:39, Craig Ringer <cr...@2ndquadrant.com> wrote:
> On 20 March 2017 at 20:57, Stas Kelvich <s.kelv...@postgrespro.ru> wrote:
>>> On 20 Mar 2017, at 15:17, Craig Ringer <cr...@2ndquadrant.com> wrote:
>>>> I thought about having special field (or reusing one of the existing 
>>>> fields)
>>>> in snapshot struct to force filtering xmax > snap->xmax or xmin = 
>>>> snap->xmin
>>>> as Petr suggested. Then this logic can reside in ReorderBufferCommit().
>>>> However this is not solving problem with catcache, so I'm looking into it 
>>>> right now.
>>> OK, so this is only an issue if we have xacts that change the schema
>>> of tables and also insert/update/delete to their heaps. Right?
>>> So, given that this is CF3 for Pg10, should we take a step back and
>>> impose the limitation that we can decode 2PC with schema changes or
>>> data row changes, but not both?
>> Yep, time is tight. I’ll try today/tomorrow to proceed with this two scan 
>> approach.
>> If I’ll fail to do that during this time then I’ll just update this patch to 
>> decode
>> only non-ddl 2pc transactions as you suggested.
> I wasn't suggesting not decoding them, but giving the plugin the
> option of whether to proceed with decoding or not.
> As Simon said, have a pre-decode-prepared callback that lets the
> plugin get a lock on the 2pc xact if it wants, or say it doesn't want
> to decode it until it commits.
> That'd be useful anyway, so we can filter and only do decoding at
> prepare transaction time of xacts the downstream wants to know about
> before they commit.

Ah, got that. Okay.

> -- 
> Craig Ringer                   http://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Training & Services

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