Re: Different execution plans for similar schemas on same query

From: Daniel Morgan <dmorgan_at_exesolutions.com>
Date: Thu, 16 May 2002 20:05:11 GMT
Message-ID: <3CE410F2.CAF8BF5D@exesolutions.com>

Leigh Gold wrote:

> Using the same query on two similar schemas (exp/imp) on 2 similar server
> (Win NT), I encountered 2 different execution plans, one uses full table
> scan (on oracle 8.1.7) and the other index scan (8.1.6). The different
> between these 2 schemas are that 1 run on 8.1.6 and the other 8.1.7.
>
> Have the optimizer changed with 8.1.7?
>
> The db_block_size is the same, both are analyzed with same sample size
> (33%). What else should I check?
>
> Thanks,
> Leigh

Yes the optimizer has changed. In fact the optmimizer changed within 8.1.6 depending on which point release you had.

But without current statistics the optimizer is just guessing and I suspect that after running the import you did not run DBMS_STATS.

Daniel Morgan Received on Thu May 16 2002 - 15:05:11 CDT