Can index be dropped and created automatically by the server?

We have Oracle 8.0.4 server running on HP-UX. Every week, a cron job is running to update the database doing some updating, inserting tasks. The default optimization is rule-based optimization. Every Sunday, a cron job is run with DBMS_Util.analyze("schema_name", "compute"). However, from week to week, the explain plan shows different path, and the index may be created or dropped for the table. The performance of course varies from week to week. Because we do not know if some body has deliberately done this or not, I wonder if some body can confirm that the index could be automatically created or dropped by the system.

It is really troublesome, your help is appreciated.

Thanks.

-James W. Received on Wed Sep 26 2001 - 19:35:02 CDT