On Thu, Sep 28, 2017 at 2:39 PM, Alvaro Herrera <alvhe...@alvh.no-ip.org> wrote: >> 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.
I was reminded of that old bug because initially, at the time, it looked very much like a corrupt index: sequential scans were fine, but index scans gave wrong answers. This is what I saw today. In the end, commit 6bfa88a fixed that old recovery bug by making sure the recovery routine heap_xlog_lock() did the right thing. In both cases (Feb 2014 and today), the index wasn't really corrupt -- it just pointed to the root of a HOT chain when it should point to some child tuple (or maybe a successor HOT chain). -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
