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From "Xiao Li (JIRA)" <>
Subject [jira] [Commented] (SPARK-11705) Eliminate unnecessary Cartesian Join
Date Sat, 28 Nov 2015 08:58:10 GMT


Xiao Li commented on SPARK-11705:

[~zzhan] You do not want to fix it by yourself? : )

> Eliminate unnecessary Cartesian Join
> ------------------------------------
>                 Key: SPARK-11705
>                 URL:
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Zhan Zhang
> When we have some queries similar to following (don’t remember the exact form):
> select * from a, b, c, d where a.key1 = c.key1 and b.key2 = c.key2 and c.key3 = d.key3
> There will be a cartesian join between a and b. But if we just simply change the table
order, for example from a, c, b, d, such cartesian join are eliminated.
> Without such manual tuning, the query will never finish if a, b are big. But we should
not relies on such manual optimization.

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