hive-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Vineet Garg (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-17767) Rewrite correlated EXISTS/IN subqueries into LEFT SEMI JOIN
Date Tue, 10 Oct 2017 23:06:00 GMT
Vineet Garg created HIVE-17767:
----------------------------------

             Summary: Rewrite correlated EXISTS/IN subqueries into LEFT SEMI JOIN
                 Key: HIVE-17767
                 URL: https://issues.apache.org/jira/browse/HIVE-17767
             Project: Hive
          Issue Type: Improvement
          Components: Query Planning
            Reporter: Vineet Garg
            Assignee: Vineet Garg


Currently such queries are written into group by + inner join with value generator and is
inefficient. Value generator consists of join with outer query to fetch all correlated values.
This value generator could be completely eliminated if such queries are instead rewritten
into LEFT SEMI JOIN.
Note that to do this first hive need to support LEFT SEMI JOIN with non-equi condition (HIVE-17766).



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)

Mime
View raw message