6 Replies Latest reply on Sep 14, 2015 11:16 AM by Steven Hawkins

    Teiid Impala LIMIT Pushdown Not Working as Expected in Some Cases

    Scott Wallace Newbie

      In Impala JDBC connection LIMIT push down to Impala does not happen in some cases causing Teiid to have to wait to project all rows before limiting results. This slows down large requests.

       

      Noticed this behavior appears to be limited to aggregation of a math operation.

       

      For example, the following case sends LIMIT to Impala.


      SELECT id, sum(metric)

      FROM

        vdb

      GROUP BY

        id

      LIMIT 25


      While this does not:


      SELECT id, sum(metric1 + metric2)

      FROM

        vdb

      GROUP BY

        id

      LIMIT 25

       

      And this does send limit:


      SELECT id, sum(metric1), sum(metric2)

      FROM

        vdb

      GROUP BY

        id

      LIMIT 25


      Any ideas what could be causing this. We are using translator-hive-8.10.0.Final.jar.