Re: bloom filter not used after 19C upgrade

Malden,

explain plan is out of question. Please stop wasting my time by mentioning it.
http://kerryosborne.oracle-guy.com/2008/10/14/explain-plan-lies/ One uses dbms_xplan.display_cursor.
If you have two plans you can compare on costs and estimates and maybe find out what influenced the decision not to use bloom filter.

Thanks

Lothar

Am 09.05.2024 um 02:53 schrieb Mladen Gogala:
> On Wed, 2024-05-08 at 23:16 +0200, Lothar Flatz wrote:
>> Hi,
>>
>> You could try hinting the bloom filter and see what happens.
>> If I get the message right decision is made at runtime. (Not sure).
>> In such case it can make a difference how well the table is cached.
>> Need more facts, e.g. both plans.
>>
>> Thanks
>>
>> Lothar
>
> Hi Lothar,
> I may be mistaken, but if the decision is made at runtime, then it is
> not possible to know in advance whether Bloom filters will be used or
> not. The only places where it's possible to see it is V$SQL_PLAN and
> V$SQL_JOIN and not explain plan.
> Other than that, Bloom filters were invented by Mr. Bloom, of the
> Bialystock & Bloom fame, from the movie "The Producers". That is what
> it's so hard to catch them. BTW, if you decide to watch the movie, a
> smart decision by any standard, I'd recommend the Gene Wilder version,
> rather than the modern one with Will Ferrell.
> Regards
>
> --
> Mladen Gogala
> Database SME
> https://dbwhisperer.wordpress.com
>

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