One can not say in general that having != in a qualification does a full table scan.
Here is a little example You have a Form where Field1 has an index. 'Field1' = "foo" would use the index defined on Field1 'Field1' = "foo" and 'Field2' != $NULL$ would use the index defined on Field1 'Field1' = "foo" and 'Field2' = "bar" would use the index defined on Field1 'Field1' != $NULL$ and 'Field2' = "bar" would not(!!) use the index defined on Field1 'Field1' = $NULL$ and 'Field2' = "bar" would not(!!) use the index defined on Field1 'Field1' != "foo" would not(!!) use the index defined on Field1 One can say that using != with an indexed field prevents the database from using that index. If your qualification does not include any other indexed field then this would result in a full table scan. HTH Kind Regards Conny -----Ursprüngliche Nachricht----- Von: Action Request System discussion list(ARSList) [mailto:[email protected]] Im Auftrag von lee Gesendet: Mittwoch, 16. September 2009 18:52 An: [email protected] Betreff: Filter qualification using != Hi, I have some filters that use the qualification != $NULL$. In the documentation it says to avoid using != as it will do a full table scan. My question is 'does having != $NULL$ AND Field1 = Organization' make the full table scan smaller? Or Is it better to do a != $NULL$ or LIKE 'CU%" When I try the LIKE qualification, it seems a lot slower (timeout message) compared to the != $NULL$ _______________________________________________________________________________ UNSUBSCRIBE or access ARSlist Archives at www.arslist.org Platinum Sponsor:[email protected] ARSlist: "Where the Answers Are" _______________________________________________________________________________ UNSUBSCRIBE or access ARSlist Archives at www.arslist.org Platinum Sponsor:[email protected] ARSlist: "Where the Answers Are"
