Re: Slow catchup of 2PC (twophase) transactions on replica in LR

On Wed, Mar 6, 2024 at 1:29 AM Давыдов Виталий <v(dot)davydov(at)postgrespro(dot)ru>
wrote:

> In usual work, the subscription has two_phase = on. I have to change this
> option at catchup stage only, but this parameter can not be altered. There
> was a patch proposal in past to implement altering of two_phase option, but
> it was rejected. I think, the recreation of the subscription with two_phase
> = off will not work.
>
>
>
The altering of two_phase was restricted because if there was a previously
prepared transaction on the subscriber when the two_phase was on, and then
it was turned off, the apply worker on the subscriber would re-apply the
transaction a second time and this might result in an inconsistent replica.
Here's a patch that allows toggling two_phase option provided that there
are no pending uncommitted prepared transactions on the subscriber for that
subscription.

Thanks to Kuroda-san for working on the patch.

regards,
Ajin Cherian
Fujitsu Australia