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Re: Poor Oracle performance? getting rid of bind variables
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Re: Poor Oracle performance? getting rid of bind variables


  • Subject: Re: Poor Oracle performance? getting rid of bind variables
  • From: Ken Anderson <email@hidden>
  • Date: Tue, 21 Aug 2007 15:52:00 -0400

According to the DBA, we're using the Rule Based Optimizer, not the Cost Based Optimizer, so therefore, no statistics.

They claim there are indexes in on the table, but running a query against user_indexes returns 0 rows.

Unfortunately, their contention is that I must be crazy, and are not paying much attention to me. There aren't any other WO developers here, so they are not very helpful when I tell them that I can do queries without bind variables.

Lastly, it's clear that JDBCExpression can't create non-bind qualifiers, since trying Chuck's hack results in getting no data back from the DB... weird.

Ken


On Aug 21, 2007, at 3:45 PM, Wiktor Moskwa wrote:

Guido Neitzer wrote:
That makes no sense if it works with non-bound variables. You need the
statistics for both ...



No you don't statistics for executing a query. In absence of them the Rule Based Optimizer was used in releases prior to 10g. I'm not sure about 10g's behaviour.

In this case statistics are probably incomplete: not available for
all necessary columns or not for all indexes. Or some indexes are missing.
On the other hand low cardinality column "Is_option_contract" can
confuse the optimizer.


Of course without knowledge about that particular table we can only
guess.

--
Wiktor Moskwa
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  • Follow-Ups:
    • Re: Poor Oracle performance? getting rid of bind variables
      • From: Wiktor Moskwa <email@hidden>
    • Re: Poor Oracle performance? getting rid of bind variables
      • From: Chuck Hill <email@hidden>
    • Re: Poor Oracle performance? getting rid of bind variables
      • From: Guido Neitzer <email@hidden>
References: 
 >Re: Poor Oracle performance? getting rid of bind variables (From: Ken Anderson <email@hidden>)
 >Re: Poor Oracle performance? getting rid of bind variables (From: Wiktor Moskwa <email@hidden>)
 >Re: Poor Oracle performance? getting rid of bind variables (From: Ken Anderson <email@hidden>)
 >Re: Poor Oracle performance? getting rid of bind variables (From: Wiktor Moskwa <email@hidden>)
 >Re: Poor Oracle performance? getting rid of bind variables (From: Guido Neitzer <email@hidden>)
 >Re: Poor Oracle performance? getting rid of bind variables (From: Wiktor Moskwa <email@hidden>)

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