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https://issues.apache.org/jira/browse/CASSANDRA-4476?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14228264#comment-14228264
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Benjamin Lerer commented on CASSANDRA-4476:
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Here are my feedbacks:
* Be carefull with whitespaces and indentation I had to use
--ignore-space-change and --ignore-whitespace to be able to apply your patch. I
had 82 lines with whitespace errors.
* {{SecondaryIndex.supportOperator}} is overloaded. Secondary indices also
support {{contains}} and {{contains key}} operators.
You ignored them completely and broke that part of the code as you will see if
you run {{ContainsRelationTest}}.
* The goal of {{SecondaryIndexSearcher.highestSelectivityPredicate}} is to
determine which index will be selecting the smallest amount of rows (highest
selectivity). There is no reason why an equal operator should select less row
than a slice operator.
* Index expressions should be grouped when multiple slices apply to the same
column. If a user does the following query Select * from myTable where a > 1
and a < 3 you should only scan from 1 to 3 and not from 1 to infinity or from
-infinity to 3.
* I have some trouble to understand the changes that you made in
{{CompositesSearcher}}. Could you add some comments to explain your approach?
* You should use meaningfull name for the test methods. Naming them {{bug4476}}
force the reader to go to JIRA to have some clue about what the method is
actualy testing.
* Using {{pageSize}} as an instance variable in {{CQLTest}} is dangerous as it
can have some unwanted effect on the other test methods (specially as JUnit
does not guarantee the method execution order since Java 7).
> Support 2ndary index queries with only inequality clauses (LT, LTE, GT, GTE)
> ----------------------------------------------------------------------------
>
> Key: CASSANDRA-4476
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4476
> Project: Cassandra
> Issue Type: Improvement
> Components: API, Core
> Reporter: Sylvain Lebresne
> Assignee: Oded Peer
> Priority: Minor
> Labels: cql
> Fix For: 3.0
>
> Attachments: 4476-2.patch, cassandra-trunk-4476.patch
>
>
> Currently, a query that uses 2ndary indexes must have at least one EQ clause
> (on an indexed column). Given that indexed CFs are local (and use
> LocalPartitioner that order the row by the type of the indexed column), we
> should extend 2ndary indexes to allow querying indexed columns even when no
> EQ clause is provided.
> As far as I can tell, the main problem to solve for this is to update
> KeysSearcher.highestSelectivityPredicate(). I.e. how do we estimate the
> selectivity of non-EQ clauses? I note however that if we can do that estimate
> reasonably accurately, this might provide better performance even for index
> queries that both EQ and non-EQ clauses, because some non-EQ clauses may have
> a much better selectivity than EQ ones (say you index both the user country
> and birth date, for SELECT * FROM users WHERE country = 'US' AND birthdate >
> 'Jan 2009' AND birtdate < 'July 2009', you'd better use the birthdate index
> first).
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