Re: Query Optimising Problem !!

-> optimising query plans There are some very simple places to start. Copy some of the SELECTS from your program into DBACCESS and put 'set explain on;' on the line above, then run the select. Look at a file called sqlexplain.out which details the query plan Informix followed. This is only from Version 4.0 onwards. The first thing to eliminate is any sequential scans on large tables by ensuring your selects use index paths. Where there is no index pathfor a WHERE clause consider creating one. Try to eliminate MATCHES and LIKE keyworkds from the slow SELECT statements. Replace them with >= and <= and IN keywords. Ensure you reguarly do an UPDATE STATISTICS especially if using Informix ONLINE. This can make quite a difference. The Informix SQL Reference and Tutorial have good chapters on optimising code. Try small changes to your slow SELECTS in dbaccess or isql and time the results (it is more accurate if you always SELECT into a TEMP TABLE). If using reports try to always ORDER EXTERNAL where possible and use index fields for any ORDER BY or GROUP BY in selects. Paul