I think Larry covered it pretty well! Dennis McGrath Software Developer QMI Security Solutions 1661 Glenlake Ave Itasca IL 60143 630-980-8461 [email protected] From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Wednesday, October 31, 2012 10:34 AM To: RBASE-L Mailing List Subject: [RBASE-L] - Re: Indexing question
Maybe Razzak can chime in to answer this one. What you said is intriguing -- my question is: are you right that even if you only query using the first column in a multi-column index it will use it? Here's why this interests me. At this client, we have an index on ShipDate by itself because we often query just by that date. However, we also have a multi-column index on ShipDate / Shipper because we often query on those 2. The index ShipDate alone would be unnecessary if we could do a multi-column instead and have it work even if you only query on the first column. I'd sure LOVE to know the answer to that one!! Karen In a message dated 10/31/2012 10:28:59 AM Central Daylight Time, [email protected]<mailto:[email protected]> writes: My understanding is that the multi column index I described would work with just IS NULL or IS NOT NULL. The where clause has to hit the index columns in the order they are defined in the index. BUT, if you only ask for the first column it will work too. Dennis McGrath
