On Fri, 2023-03-31 at 13:46 +0000, Arnaud Lesauvage wrote: > I have a long running query that I seem unable to either cancel or terminate. > What could be the reason for this, and what is the bet way to terminate this kind of query ? > > The query is a CTE using postgis ST_ClusterDBSCAN function. The CTE returns approximately 150k rows. > The SQL is as follows : > > EXPLAIN ANALYZE > WITH subq AS ( > SELECT id, geom, ST_ClusterDBSCAN(geom, eps := 1000, minpoints := 1) OVER() AS cluster_id > FROM mytable > ) > SELECT cluster_id, count(id), ST_Collect(geom) > FROM subq > GROUP BY cluster_id; > > pg_stat_activity show no wait event. > pg_cancel_backend(mypid) returns true but the state does not change in pg_stat_activity. > pg_terminate_backend(mypid) yields the same result (as superuser) > Pg_stat_activity show no wait_event. > > SELECT version(); > PostgreSQL 14.5 (Ubuntu 14.5-1.pgdg20.04+1) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0, 64-bit The most likely explanation is that one of the PostGIS functions runs for a long time without checking CHECK_FOR_INTERRUPTS(). That would be a PostGIS bug. Try to construct a reproducible test case that you can share! Perhaps this trick can help: https://www.cybertec-postgresql.com/en/cancel-hanging-postgresql-query/ Yours, Laurenz Albe
