On 07/23/2015 11:31 AM, Spiros Ioannou wrote:
Well, so far with commit_delay=0 no problems. I will report back of couse if something happens, but I believe that the problem may indeed be solved/masked with that setting. Rough description of our setup, or how to reproduce: * Timeseries data in table , say, "measurements", size: 3-4TB, about 1000 inserts/second * table measurements also has a trigger on insert to also insert on measurements_a (for daily export purposes) Just the above would cause a stuck query after a few days. Now for exporting we run the following CTE query (measurements_b is an empty table, measurements_a has about 5GB) * WITH d_rows AS (DELETE FROM measurement_events_a RETURNING * ) INSERT INTO measurement_events_b SELECT * FROM d_rows; The above caused the problem to appear every time, after a 10-20 minutes.
I was able to reproduce something like this with pgbench, by running a custom little module that calls the WaitXLogInsertionsToFinish() in a tight loop, and checks that the value it returns moves monotonically forward. With commit_delay on, once every minute or so, it moves backwards.
I'll investigate why that happens... - Heikki -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
