Basically, $subject says it all. It's pretty easy to reproduce: delete all the records from a large table and execute any sequentially scanning query before autocvacuum comes around and cleans the table up; the query will be uncancellable. This can result in fairly pathological behavior in i/o constrained systems because the query will bog itself down writing out hint bits for minutes or hours without any way to cancel or effective i/o throttling (unlike vacuum).
IMO, this should be backpatched, and is likely fixed by injecting an interrupts check at a strategic location. But where? I was thinking in heapgetpage() but here are no checks elsehwere in heapam.c which is a red flag. merlin -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
