Re: ALTER TABLE ADD COLUMN fast default

>>>>> "Andrew" == Andrew Dunstan <andrew@dunslane.net> writes:

 Andrew> I'd be curious to know how this state came about.

Me too, but available information is fairly sparse: PG 12.5, in a
container, backing a (personal) instance of Gitlab; the only database
admin operations should have been those done by Gitlab itself, but I
have not audited that codebase. No information on any history of
crashes. The missing pg_attrdef row appeared to be missing or not
visible in the heap, not just missing from indexes; it did not show up
in queries whether seqscan or indexscan was used. Available time did not
permit trying to use pageinspect on pg_attrdef.

This gitlab ticket refers to the same incident:

https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/6047

(which actually contains a new relevant fact that hadn't been mentioned
in the IRC discussion, which is that the problem affected multiple
tables, not just one.)

-- 
Andrew (irc:RhodiumToad)