A. Kretschmer wrote: > am Fri, dem 28.09.2007, um 11:56:46 -0400 mailte Mike Charnoky folgendes: > > Hi, > > > > I am still having problems performing a count(*) on a large table. This > > > > 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: > > Again: an index can't help! Because of MVCC: 'select count(*)' without > WHERE-condition forces an seq. table-scan. But he does have a WHERE condition. THe problem is, probably, that the condition is not selective enough so the planner chooses to do a seqscan. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc. ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
