Re: logical decoding of two-phase transactions

On Fri, Feb 3, 2017 at 7:08 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2017-02-03 18:47:23 -0500, Robert Haas wrote:
>> On Fri, Feb 3, 2017 at 6:00 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>> > I still haven't seen a credible model for being able to apply a stream
>> > of interleaved transactions that can roll back individually; I think we
>> > really need the ability to have multiple transactions alive in one
>> > backend for that.
>>
>> Hmm, yeah, that's a problem. That smells like autonomous transactions.
>
> Unfortunately the last few proposals, like spawning backends, to deal
> with autonomous xacts aren't really suitable for replication, unless you
> only have very large ones. And it really needs to be an implementation
> where ATs can freely be switched inbetween. On the other hand, a good
> deal of problems (like locking) shouldn't be an issue, since there's
> obviously a possible execution schedule.
>
> I suspect this'd need some low-level implemention close to xact.c that'd
> allow switching between transactions.

Yeah. Well, I still feel like that's also how autonomous transactions
oughta work, but I realize that's not a unanimous viewpoint. :-)

--
Robert Haas
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