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From Ted <r6squee...@gmail.com>
Subject Re: Bloom Filter analogy in SQL
Date Tue, 16 Apr 2013 00:58:32 GMT
believe it or not, wikipedia has an excellent description of bloomfilters

http://en.wikipedia.org/wiki/Bloom_filter

On 4/16/13, Anupam Singh <avsingh@gmail.com> wrote:
> Many join implementations use bloom filters built on the smaller to
> eliminate rows on the larger tables in SQL queries. Many industrial RDBMS
> engines will show the use of bloom filters in SQL explain plans.
>
>
> For instance, oracle explain plans call these joins bloom filters as
> SYS_OP_BLOOM_FILTER :-
>
>
> https://forums.oracle.com/forums/thread.jspa?threadID=2470938
>
>
> It could be useful for performance tuning. Hope this helps.
>
>
> -Anupam
>
> —
> Sent from Mailbox for iPhone
>
> On Fri, Mar 29, 2013 at 11:32 PM, Ted Dunning <tdunning@maprtech.com>
> wrote:
>
>> This isn't a very Hadoop question.
>> A Bloom filter is a very low level data structure that doesn't really any
>> correlate in SQL.  It allows you to find duplicates quickly and
>> probabilistically.  In return for a small probability of a false
>> positive,
>> it uses less memory.
>> On Fri, Mar 29, 2013 at 5:36 PM, Sai Sai <saigraph@yahoo.in> wrote:
>>> Can some one give a simple analogy of Bloom Filter in SQL.
>>> I am trying to understand and always get confused.
>>> Thanks
>>>


-- 
Ted.

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