Eric Comeau <ecomeau@xxxxxxxxxxxx> writes: > 2010-10-16 05:55:52 EDT [6334]: [1-1] LOG: duration: 5572.517 ms > statement: EXECUTE <unnamed> [PREPARE: COMMIT] > 2010-10-16 06:06:24 EDT [26856]: [1-1] LOG: duration: 5617.866 ms > statement: EXECUTE <unnamed> [PREPARE: COMMIT] > 2010-10-16 06:06:24 EDT [20740]: [13-1] LOG: duration: 5210.190 ms > statement: EXECUTE <unnamed> [PREPARE: COMMIT] > 2010-10-16 08:24:06 EDT [8743]: [1-1] LOG: duration: 6487.346 ms > statement: EXECUTE <unnamed> [PREPARE: COMMIT] > Questions; > 1) What do these statements mean? They appear to be COMMIT commands. (It's pretty stupid to be using the PREPARE/EXECUTE machinery to execute a COMMIT, but that's evidently what your client-side code is doing.) > 2) How do I dig deeper to determine why they are taking longer than 5 secs. My guess would be overstressed disk subsystem. A COMMIT doesn't require much except fsync'ing the commit WAL record down to disk ... but if the disk is too busy to process that request quickly, you might have to wait. It also seems possible that the filesystem is interlocking the fsync on the WAL file with previous writes to other files. Anyway, watching things with vmstat or iostat to see if there's an activity spike when this is happening would confirm or refute that idea. [ thinks for a bit ... ] Actually, it's possible that the COMMIT command is doing nontrivial work before it can really commit. Perhaps you have deferred foreign keys to check? regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
