Re: Segfault on ANALYZE in SERIALIZABLE isolation

I wrote:
> Sergei Kornilov <sk@zsrv.org> writes:
>> I can reproduce with:
>> set default_transaction_isolation TO serializable ;
>> analyze ;

> So the problem is that something is passing a null snapshot to something
> that isn't expecting that.  This seems closely related to the tableam
> API issue that was being debated a day or two back about whether it's
> ever valid to hand a null snapshot to an AM.  Andres, which layer do
> you think is at fault here?

Bisecting confirms that this broke at

commit 737a292b5de296615a715ddce2b2d83d1ee245c5
Author: Andres Freund <andres@anarazel.de>
Date:   Sat Mar 30 16:21:09 2019 -0700

    tableam: VACUUM and ANALYZE support.

I'd thought possibly this had something to do with bb16aba50 (Enable
parallel query with SERIALIZABLE isolation) but the bisection result
makes it pretty clear that it's just a tableam API screwup.

            regards, tom lane