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From "daniel (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DRILL-4157) Add LIMIT push down rule for relational database sources
Date Thu, 03 Dec 2015 14:43:11 GMT
daniel created DRILL-4157:
-----------------------------

             Summary: Add LIMIT push down rule for relational database sources
                 Key: DRILL-4157
                 URL: https://issues.apache.org/jira/browse/DRILL-4157
             Project: Apache Drill
          Issue Type: New Feature
          Components: Storage - Other
            Reporter: daniel


Hi,

It will be very useful if queries with LIMIT or OFFSET clauses could be translated to native
SQL when using relational databases as input.

Supose that I have a mysql connection configured. Right now, if I execute:

select * from mysql.schema.table LIMIT 1

This will be translated into:

select * from schema.table

And executed in the relational database server. As you can see, all the rows will be retrieved
from the table. Then, apache drill will filter the result and show only one row.

The problem is that this is a huge performance penalty that can be avoided translating the
query having this into account.


I'm not quite sure if this is a mysql problem or all the relational database sources share
the same limitation. So, excuse me if I open this issue as a feature request.

Regards



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