Mike Charnoky wrote: > Hi, > > I am still having problems performing a count(*) on a large table. This > is a followup from a recent thread: > > http://archives.postgresql.org/pgsql-general/2007-09/msg00561.php > > Since the last time these problems happened, we have tweaked some > postgresql config parameters (fsm, etc). I also recreated the large > table, with the assumption it was somehow corrupted. > > Now, certain count(*) queries are failing to complete for certain time > ranges (I killed the query after about 24 hours). The table is indexed > on a timestamp field. Here is one query that hangs: > > select count(*) from mytable where evtime between '2007-09-26' and > '2007-09-27'; > > However, this query runs successfully and takes 2 minutes: > > select count(*) from mytable where evtime between '2007-09-25' and > '2007-09-26'; > > count > ---------- > 14150928 > (1 row) > > What is going on? I analyzed the table before running the query and > have no reason to believe that the amount of data added to the table > varies much from day to day. No data has been deleted from the table > yet, just added. > > Here is some config info: > > PostgreSQL 8.1.8 on Fedora 3 Have you vacuumed recently? Sean ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
