Re: Assertion failure in SnapBuildInitialSnapshot()

On Tue, Nov 15, 2022 at 8:08 AM Andres Freund <andres@anarazel.de> wrote:
>
> On 2022-11-14 17:25:31 -0800, Andres Freund wrote:
> > Hm, also, shouldn't the patch adding CRS_USE_SNAPSHOT have copied more of
> > SnapBuildExportSnapshot()? Why aren't the error checks for
> > SnapBuildExportSnapshot() needed? Why don't we need to set XactReadOnly? Which
> > transactions are we even in when we import the snapshot (cf.
> > SnapBuildExportSnapshot() doing a StartTransactionCommand()).
>
> Most of the checks for that are in CreateReplicationSlot() - but not al,
> e.g. XactReadOnly isn't set,
>

Yeah, I think we can add the check for XactReadOnly along with other
checks in CreateReplicationSlot().

> nor do we enforce in an obvious place that we
> don't already hold a snapshot.
>

We have a check for (FirstXactSnapshot == NULL) in
RestoreTransactionSnapshot->SetTransactionSnapshot. Won't that be
sufficient?

-- 
With Regards,
Amit Kapila.