Re: An ancient mystery

From: Madhu Sreeram <>
Date: Sat, 22 Nov 2008 10:02:43 -0600
Message-ID: <>

Here is a thought.
May be some implicit data conversion is happening? For example, assuming the query involves bind values, passing a number type instead of character type can lead to "unexpected" behavior. The table has possibly grown large enough that you are able to feel the "pain" now.

-Madhu Sreeram

On Thu, Nov 20, 2008 at 9:05 PM, Dennis Williams <> wrote:

> List,
> The situation:
> Oracle 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

Received on Sat Nov 22 2008 - 10:02:43 CST

Original text of this message