Peter Geoghegan wrote: > We certainly do still see wrong answers to queries here: > > postgres=# select ctid, xmin, xmax, * from t; > ctid | xmin | xmax | id | name | x > -------+-------+------+----+------+--- > (0,1) | 21171 | 0 | 1 | 111 | 0 > (0,7) | 21177 | 0 | 3 | 333 | 5 > (2 rows) > > postgres=# select * from t where id = 3; > id | name | x > ----+------+--- > 3 | 333 | 5 > (1 row) > > postgres=# set enable_seqscan = off; > SET > postgres=# select * from t where id = 3; > id | name | x > ----+------+--- > (0 rows)
Yeah, oops. > FWIW, I am reminded a little bit of the MultiXact/recovery bug I > reported way back in February of 2014 [1], which also had a HOT > interaction that caused index scans to give wrong answers, despite > more or less structurally sound indexes. > > [1] > https://www.postgresql.org/message-id/CAM3SWZTMQiCi5PV5OWHb+bYkUcnCk=o67w0csswpvv7xfuc...@mail.gmail.com Thanks for the reference. I didn't remember this problem and it's not (wasn't) in my list of things to look into. Perhaps these are both the same bug. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
