[jira] [Created] (IMPALA-10781) Avoid nested loop join when there is OR in the join condition

["Csaba Ringhofer (Jira)" <ji...@apache.org>]

Csaba Ringhofer created IMPALA-10781:
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             Summary: Avoid nested loop join when there is OR in the join condition
                 Key: IMPALA-10781
                 URL: https://issues.apache.org/jira/browse/IMPALA-10781
             Project: IMPALA
          Issue Type: Improvement
          Components: Backend, Frontend
            Reporter: Csaba Ringhofer


The following query becomes a nested loop join in Impala:
{code}
SELECT * FROM t1 JOIN  t2 ON t1_col1 = t2_col1 OR t1_col2 = t2_col2;
{code}

A possible solution is to rewrite the join into an union of two joins where each join becomes an equi join. Currently this has to be done by hand.

It is possible to create a more efficient solution that doesn't need to reread the right side of the join by adding an operator that duplicates rows and adds an extra column that identifies the join condition.




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