Re: [BUG] Error in BRIN summarization

On Mon, Jul 27, 2020 at 10:25 AM Alvaro Herrera
<alvherre@2ndquadrant.com> wrote:
> (I was also considering whether it needs to be a loop to reobtain root
> tuples, in case a concurrent transaction can create a new item while
> we're checking that item; but I don't think that can really happen for
> one individual tuple.)

I wonder if something like that is the underlying problem in a recent
problem case involving a "REINDEX index
pg_class_tblspc_relfilenode_index" command that runs concurrently with
the regression tests:

https://postgr.es/m/CAH2-WzmBxu4o=pMsniur+bwHqCGCmV_AOLkuK6BuU7ngA6evqw@mail.gmail.com

We see a violation of the HOT invariant in this case, though only for
a system catalog index, and only in fairly particular circumstances
involving concurrency.

-- 
Peter Geoghegan