Re: ERROR after writing PREPARE WAL record

On Wed, Jul 17, 2019 at 7:08 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Asim R P <apraveen(at)pivotal(dot)io> writes:
> > Cancel/terminate requests are held off during "PREPARE TRANSACTION"
> > processing in function PrepareTransaction(). However, a subroutine
invoked
> > by PrepareTransaction() may perform elog(ERROR) or elog(FATAL).
>
> The correct response, if you notice code doing that, is to fix it so
> it doesn't do that. Typically the right answer is to move the
> failure-prone operation to pre-commit processing.

Thank you for the response. There is nothing particularly alarming. There
is one case in LWLockAcquire that may error out if (num_held_lwlocks >=
MAX_SIMUL_LWLOCKS). This problem also exists in CommitTransaction() and
AbortTransaction() code paths. Then there is arbitrary add-on code
registered as Xact_callbacks.

SyncRepWaitForLSN() directly checks ProcDiePending and QueryCancelPending
without going through CHECK_FOR_INTERRUPTS and that is for good reason.
Moreover, it only emits a WARNING, so no problem there.

Asim