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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-7391) Partial indexes
Date Thu, 12 Jun 2014 19:35:01 GMT
Jonathan Ellis created CASSANDRA-7391:
-----------------------------------------

             Summary: Partial indexes
                 Key: CASSANDRA-7391
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7391
             Project: Cassandra
          Issue Type: New Feature
          Components: API, Core
            Reporter: Jonathan Ellis
            Priority: Minor
             Fix For: 3.0


Indexing extremely common values is not useful (e.g. where 90% of rows have a null value)
because it's actually more efficient to just to a seq scan, so indexing is just wasted effort.

Rather than requiring users to take that hit if they want anything indexed at all, we should
allow specifying a WHERE clause to CREATE INDEX specifying which rows to include in the index.
 Could include UDF but useful even without it.

http://www.postgresql.org/docs/9.3/static/indexes-partial.html



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