On 2020-Jul-28, Peter Geoghegan wrote: > On Mon, Jul 27, 2020 at 10:25 AM Alvaro Herrera > <alvhe...@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_aolkuk6buu7nga6e...@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.
Hmm. As far as I understand, the bug Anastasia reports can only hit an index build that occurs concurrently to heap updates; and that cannot happen for a regular index build, only for CREATE INDEX CONCURRENTLY and REINDEX CONCURRENTLY. So unless I miss something, it's not related to that other bug. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
