RE: Bloom Filter Partition Pruning

From: Jaromir D.B.Nemec <jaromir_at_db-nemec.com>
Date: Fri, 16 Mar 2018 07:48:20 +0100
Message-ID: <16d601d3bcf2$c72ed8c0$558c8a40$_at_db-nemec.com>



Hi Sayan,  

That answers my question only indirectly.

Yes, a given set of keys from TABLEB can be mapped using ORA_HASH() to a (exact) list of partitions of TABLEA, that contains those keys.

The cross (in my understanding) is that only the Bloom Filter is passed – not the exact key set from TABLEB.

I can only speculate that along the BF also the list of partitions from TABLEA that are relevant is passed (constructed as described above) - this is the point I’d like to clarify.    

Kind Regards,  

Jaromir D.B. Nemec

 <http://www.db-nemec.com> http://www.db-nemec.com  

From: Sayan Malakshinov [mailto:xt.and.r_at_gmail.com] Sent: Freitag, 16. März 2018 00:29
To: jaromir_at_db-nemec.com
Cc: ORACLE-L <oracle-l_at_freelists.org> Subject: Re: Bloom Filter Partition Pruning  

Jaromir,  

That's pretty simple for HASH partitioning:

Oracle can use hashes of elements for BF the same way as it uses them for usual partition pruning for hash-partitioned tables, so all that we need is just number of partitions (https://jonathanlewis.wordpress.com/2009/11/21/ora_hash-function/)    

-- 

Best regards,
Sayan Malakshinov

http://orasql.org



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Received on Fri Mar 16 2018 - 07:48:20 CET

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