> Hi, > could somebody explain me please why following select > SELECT docid FROM prod.guids > GROUP BY docid HAVING( COUNT(docid) > 1 ) > > taking 15 min on 2 Proc Box on 1M rows, where number of duplicates > around 300K, > and docid indexed and not null and char(16). > > May be I am doing something wrong? > Thank you.
I would first perform an "explain" on the query to have the database show you where it is spending its time. Second, you are performing a full table scan. Try this: select count(docid) from prod.guids See how long that takes, that's about as fast as your system will handle that query. If that query is fast, you may need to play with the tuning parameters of PostgreSQL like "sort memory." Have you adjusted any parameters in your postgresql.conf file? ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
