RE: Why the optimizer is not choosing the best plan?

Hi Ryan

1. The OP is probably using 8i. Therefore he cannot use system stats = anyway.
2. As usually it depends on your system... I did very good experiences = with them! The impact on the CBO can be huge. The most evident is that = db_file_multiblock_read_count isn't used for costing full table scan.

Chris

>-----Original Message-----
>From: oracle-l-bounce_at_freelists.org =

[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of
>ryan_gaffuri_at_comcast.net
>Sent: 21 October 2004 15:31
>To: JozeS_at_hermes-plus.si; oracle-l_at_freelists.org
>Cc: Joze Senegacnik
>Subject: RE: Why the optimizer is not choosing the best plan?
>
>we are using system stats here and we have noticed absolutely no =
difference whatsoever in oracles
>ability to make the best plan over using optimizer parameters. I've =
also noticed that even with bad
>optimizer init.ora settings in 9.2 the CBO is still write about 99% of =
the time.
>with decent settings that improves to 99.5% of the time. so if system =
stats helps its minimal.
>
>-------------- Original message --------------
>
>> If you are on 9i then you should try to gather system statistics. =
This =3D
>> may change the join method from NL to HJ.
>>
>> Regards, Joze=3D20
>>
>> -----Original Message-----
>> From: oracle-l-bounce_at_freelists.org =3D
>> [mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Sami Seerangan
>> Sent: Wednesday, October 20, 2004 9:49 PM
>> To: Oracle Discussion List
>> Subject: Why the optimizer is not choosing the best plan?
>>
>
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