Re: logical decoding of two-phase transactions

On 28 March 2017 at 05:25, Andres Freund <andres@anarazel.de> wrote:

> On a very quick skim, this doesn't seem to solve the issues around
> deadlocks of prepared transactions vs. catalog tables.  What if the
> prepared transaction contains something like LOCK pg_class; (there's a
> lot more realistic examples)? Then decoding won't be able to continue,
> until that transaction is committed / aborted?

Yeah, that's a problem and one we discussed in the past, though I lost
track of it in amongst the recent work.

I'm currently writing a few TAP tests intended to check this sort of
thing, mixed DDL/DML, overlapping xacts, interleaved prepared xacts,
etc. If they highlight problems they'll be useful for the next
iteration of this patch anyway.

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