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From asteri...@googlecode.com
Subject Re: Issue 924 in asterixdb: Secondary btree index should not have a bloomfilter on it since the filter is not used for range search which is always the case for secondary index search
Date Tue, 11 Aug 2015 16:03:51 GMT

Comment #4 on issue 924 by kiss...@gmail.com: Secondary btree index should  
not have a bloomfilter on it since the filter is not used for range search  
which is always the case for secondary index search
https://code.google.com/p/asterixdb/issues/detail?id=924

Discussion conclusion: secondary btree index will not have a bloomfilter on  
it.

The reasons are as follows:
1. Secondary btree index search can't use Bloomfilter for range searches  
since , in general, Bloomfilter can only be used for point lookup, i.e.,  
single value equality predicate on the indexed key such as user_id (primary  
key field) = 10.
2. Secondary btree index search can't use Bloomfilter for point lookup  
either such as price = 20 since Bloomfilter in secondary btree index  
captures not only secondary key but also primary key, but search predicate  
only includes secondary key.
3. Delete operation in secondary index may use the Bloomfilter to check the  
existence of the entry to be deleted, but the entry to be deleted will  
exist always when the delete operation is executed since the delete  
operation always preceded by the search operation. So, checking Bloomfilter  
in the situation is useless overhead.
Based on 1,2, and 3, Bloomfilter on secondary btree index is useless.  
Therefore, this will be removed.

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