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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Oracle Performance
RE: Oracle PerformanceThat is Interesting, If I argued is because it could confuse a newbie,
he could understand: "Why don't you use rule, is better than cbo"
Maybe I wasn't clear enough. I use the Rule hint for troubleshooting. If it works much faster with the Rule hint, obviously something else needs investigating like analyzing tables or using histograms. If using Rule is slower, that also gives me some ideas. If using Rule doesn't make any difference and the SQL is still slow, maybe there needs to be an index or some other way of writing the SQL.
Using the Rule hint is a good, quick troubleshooting method but not normally the fix.
Jerry Whittle
ASIFICS DBA
NCI Information Systems Inc.
jerome.whittle_at_scott.af.mil
618-622-4145
-----Original Message-----
From: Juan Cachito Reyes Pacheco [SMTP:jreyes_at_dazasoftware.com]
Honestly I don't agree with this, I don't think there is any need to use rule, in Oracle 9i, CBO works perfectly with this kind of situation, the problem must be find and fixed.
You have 5 indexes of which 3 have the fields in your SQL. You may be better off with one index on the COD_IMPORTACION, COD_NIVEL_CALIDAD, and NRO_FACTURACION fields. After creating the index, analyze the table before running your sql.
You might also just want to try to use the Rule hint. It's usually one of the first things I try with slow SQL. If it runs much faster with the Rule hint, something is going on to confuse the CBO.
SELECT /*+ RULE */ COUNT(NRO_FACTURACION) ....
Jerry Whittle
ASIFICS DBA
NCI Information Systems Inc.
jerome.whittle_at_scott.af.mil
618-622-4145
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