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Comments for Granular Control of Optimizer Features (OPTIMIZER_FEATURES_ENABLED, _FIX_CONTROL, V$SYSTEM_FIX_CONTROL and V$SESSION_FIX_CONTROL)


Jm said...

Please clarify - if Oracle has identified a bug then bug should be fixed in subsequent releases or patches.
But then
-> Why does oracle leave identified bugs as off (I am assuming means bug fixes are disabled)
-> If bugs are not off, then what's the purpose of having an ability to make it off

Thanks

Tim... said...

Hi.

Not sure what you are saying. All those bug listed here have a default VALUE of 1, meaning they are on by default. they have an IS_DEFAULT of 1, meaning this is a default value. How does this mean they are off by default? Are you maybe reading the EVENT column by accident?

Even if this were not true, you can enable or disable a bug fix using this command, not just disable them. :)

Cheers

Tim...

Jm said...

Hi Tim-

Thanks for the clarification. On 12.1.0.2 version, I have 79 bug fixes which are off. I haven't done anything explicitly. Though is_default = 1. Not sure how.

SQL> select count(*) from V$SYSTEM_FIX_CONTROL where value = 0 and is_default = 1 ;

COUNT(*)
----------
79

Further -> I am still trying to understand (thick head, sorry) the need of making a bugfix off.

Tim... said...

Hi.

OK. The second part of the question is easy. No. Don't change them. Leave all defaults unless directed to change them by support or a relevant MOS note for a problem you are having.

Some of the "fixes" may not be on by default for fear of affecting backwards compatibility etc. Defaults are fine unless you need a specific change.

Cheers

Tim...

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