Re: Hints and RBO?

From: Philip Chee <philip_at_aleytys.pc.my>
Date: Sat, 14 Oct 2000 15:18:58 GMT
Message-ID: <971536738.5418snx@aleytys.pc.my>

In article <1279.321T496T12073331lothar.armbruester_at_rheingau lothar.armbruester_at_rheingau.vistec.net writes:
>Bill Buchan wrote at 13-Okt-00 17:46:36 on the subject "Hints and RBO?":
 

>>However if I put HINTs in my SQL the EXPLAIN PLAN changes; therefore
>>the optimizer is responding to the hints.
 

>>I thought that you could only use hints with CBO?
>
>No, there are some hints that indicate the CBO and others that indicate
>RBO (e.g. /*+ RULE */ ;-) Hints like /*+ FIRST_ROWS */ or /*+ ALL_ROWS */
>and the like indicate CBO. Hints like /*+ INDEX */ or /*+ FULL */ do work
>with both optimizers (AFAIK).

I had a case where FIRST_ROWS changed a query plan when there were NO statistics. That was way back on 7.0.13.

Philip

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 Philip Chee: Tasek Corporation Berhad, P.O.Box 254, 30908 Ipoh, MALAYSIA   e-mail: philip_at_aleytys.pc.my Voice:+60.5.291.1011 Fax:+60.5.291.9932    Guard us from the she-wolf and the wolf, and guard us from the thief,

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Received on Sat Oct 14 2000 - 10:18:58 CDT