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From "Shawn Lavelle (JIRA)" <>
Subject [jira] [Created] (SPARK-19730) Predicate Subqueries do not push results of subqueries to data source
Date Fri, 24 Feb 2017 18:04:44 GMT
Shawn Lavelle created SPARK-19730:

             Summary: Predicate Subqueries do not push results of subqueries to data source
                 Key: SPARK-19730
             Project: Spark
          Issue Type: Bug
          Components: Optimizer, SQL
    Affects Versions: 2.1.0
            Reporter: Shawn Lavelle

When a SparkSQL query contains a subquery in the where clause, such as a predicate query using
the IN operator, the results of that subquery are not pushed down as a fileter to the DataSourceAPI
for the outer query. 

Select point, time, value from data where time between now()-86400 and now() and point in
(select point from groups where group_id=5);

Two queries will be sent to the data Source.  One for the subquery, and another for the outer
query. The subquery works correctly returning the points in the group, however, outer query
does not push a filter for point column.

The "group" table has a few hundred rows to group a few hundred thousand points.  The data
table has several billion rows keyed by point and time.  Without the ability to push down
the filters for the columns of outer the query, the data source cannot properly conduct its
pruned scan.

The subquery results should be pushed down to the outer query as an IN Filter with the results
of the subquery.

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