ignored indexes

Posted in 2003

Topics: Performance & Tuning, Security, Permissions & Auditing

Juan Ignacio Carbajal Rivera — Thu, 29 May 2003 13:28:21 -0500 — source: Usenet: comp.databases.informix

Hi you all; what may influence a query make a sequential scan even though the column is being queried is indexed? regards *********************************** Juan I Carbajal R. AUDITOR DE FRAUDE INTERNACIONAL INTERNATIONAL FRAUD AUDITOR RADIOMOVIL DIPSA SA de CV AV Ej'rcito NAL #488 Col. Polanco 011(52)55-56253700 ext 2489

↪ replying to Juan Ignacio Carbajal Rivera

John Carlson — Thu, 29 May 2003 15:06:55 -0400 — source: Usenet: comp.databases.informix

On Thu, 29 May 2003 13:28:21 -0500, Juan Ignacio Carbajal Rivera <jcarbajal@mail.telcel.com> wrote: Out-of-date table statistics? Please post SQL and schema. > >Hi you all; >what may influence a query make a sequential scan >even though the column is being queried is >indexed? >regards > > >*********************************** >Juan I Carbajal R. >AUDITOR DE FRAUDE INTERNACIONAL >INTERNATIONAL FRAUD AUDITOR >RADIOMOVIL DIPSA SA de CV >AV Ej'rcito NAL #488 Col. Polanco >011(52)55-56253700 ext 2489

↪ replying to Juan Ignacio Carbajal Rivera

Fernando Nunes — Thu, 29 May 2003 22:01:46 +0100 — source: Usenet: comp.databases.informix

Juan Ignacio Carbajal Rivera wrote: > Hi you all; > what may influence a query make a sequential scan > even though the column is being queried is > indexed? . No UPDATE STATISTICS . Index in "DISABLED" state . Estimated number of rows is a very significant percentage of the number of table rows . Any operation on the indexed column: Never do this: WHERE column - 5 = Y Do this instead: WHERE column = Y + 5 Regards