Re: Making all nbtree entries unique by having heap TIDs participate in comparisons

On Wed, Aug 1, 2018 at 9:48 PM, Andrey Lepikhov
<a(dot)lepikhov(at)postgrespro(dot)ru> wrote:
> I use v3 version of the patch for a Retail Indextuple Deletion and from time
> to time i catch regression test error (see attachment).
> As i see in regression.diff, the problem is instability order of DROP ...
> CASCADE deletions.
> Most frequently i get error on a test called 'updatable views'.
> I check nbtree invariants during all tests, but index relations is in
> consistent state all time.
> My hypothesis is: instability order of logical duplicates in index relations
> on a pg_depend relation.
> But 'updatable views' test not contains any sources of instability:
> concurrent insertions, updates, vacuum and so on. This fact discourage me.
> May be you have any ideas on this problem?

It's caused by an implicit dependency on the order of items in an
index. See https://www.postgresql.org/message-id/20180504022601.fflymidf7eoencb2%40alvherre.pgsql.

I've been making "\set VERBOSITY terse" changes like this whenever it
happens in a new place. It seems to have finally stopped happening.
Note that this is a preexisting issue; there are already places in the
regression tests where we paper over the problem in a similar way. I
notice that it tends to happen when the machine running the regression
tests is heavily loaded.

--
Peter Geoghegan