"Alvaro Herrera" <alvherre@xxxxxxxxxxxxxxxxx> writes: > 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. What does EXPLAIN SELECT ... say? -- Gregory Stark EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@xxxxxxxxxxxxxx so that your message can get through to the mailing list cleanly
