Is partitioning or another feature that implies the cost based optimiser in use? On 11/21/08, Dennis Williams <oracledba.williams@xxxxxxxxx> wrote: > List, > > The situation: > > Oracle 8.1.7.4 database on Solaris 8 (soon to be upgraded to 10g) > Rule-based Optimizer > > A query which has run for years using an indexed access to a very large > table (maybe 100 million rows) > suddenly decides to use a full-table scan, shutting down a critical business > process. > > Then after several hours, it switches back to using the index. > All concerned claim that nothing changed before or after. > > Needless to say the business users are nervous. They think maybe the > database grew beyond some limit. > > Can anyone think of an explanation? > > Thanks, > Dennis Williams > -- Sent from Google Mail for mobile | mobile.google.com Niall Litchfield Oracle DBA http://www.orawin.info -- //www.freelists.org/webpage/oracle-l