GitHub user ravipesala opened a pull request:
https://github.com/apache/spark/pull/3249
[SPARK-4226][SQL] SparkSQL - Add support for subqueries in predicates('in'
clause)
This PR supports subqueries in preicates 'in' clause. The queries will be
transformed to the LeftSemi join as mentioned below.
Case 1 Uncorelated queries
-- original query
select C
from R1
where R1.A in (Select B from R2)
-- rewritten query
Select C
from R1 left semijoin R2 on R1.A = R2.B
Case 2 Corelated queries
-- original query
select C
from R1
where R1.A in (Select B from R2 where R1.X = R2.Y)
-- rewritten query
select C
from R1 left semi join
(select B, R2.Y as sq1_col0 from R2) sq1
on R1.X = sq1.sq1_col0 and R1.A = sq1.B
Restriction : Alias need to be used as we convert it into join queries.
Complete specification is available in
https://issues.apache.org/jira/secure/attachment/12614003/SubQuerySpec.pdf
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/ravipesala/spark SPARK-4226
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/3249.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #3249
----
commit b670862276d828d94ca5da94a22944e98f8aaa55
Author: ravipesala <[email protected]>
Date: 2014-11-13T18:02:12Z
Supporting subqueries inside where 'in' clause
commit ccaddcb8c3229ba039c74acb8172f97ca99ffba1
Author: ravipesala <[email protected]>
Date: 2014-11-13T18:03:29Z
Added new expression class
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