[jira] [Resolved] (TAJO-1277) GreedyHeuristicJoinOrderAlgorithm sometimes wrongly assumes associativity of joins

["Jihoon Son (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TAJO-1277?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jihoon Son resolved TAJO-1277.
------------------------------
    Resolution: Fixed

I committed the patch.
[~sirpkt], thanks for your contribution!

> GreedyHeuristicJoinOrderAlgorithm sometimes wrongly assumes associativity of joins
> ----------------------------------------------------------------------------------
>
>                 Key: TAJO-1277
>                 URL: https://issues.apache.org/jira/browse/TAJO-1277
>             Project: Tajo
>          Issue Type: Bug
>            Reporter: Keuntae Park
>            Assignee: Keuntae Park
>
> It looks like GreedyHeuristicJoinOrderAlgorithm always assumes every joins are associative.
> Following query returns in inaccurate result:
> {code}
> select * FROM
> customer c 
> right outer join nation n on c.c_custkey = n.n_nationkey
> join region r on c.c_custkey = r.r_regionkey;
> {code}
> because GreedyHeuristicJoinOrderAlgorithm changes join order as
> {code}
> select * FROM
> customer c 
> join region r on c.c_custkey = r.r_regionkey
> right outer join nation n on c.c_custkey = n.n_nationkey;
> {code}
> I think getBestPair() should be fixed to avoid wrong join ordering. 



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