Re: An ancient mystery
- From: "Madhu Sreeram" <madhusreeram@xxxxxxxxx>
- To: oracledba.williams@xxxxxxxxx
- Date: Sat, 22 Nov 2008 10:02:43 -0600
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 <
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
>
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