Haisheng Yuan created CALCITE-3968:
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             Summary: Disable JoinPushThroughJoinRule.left by default
                 Key: CALCITE-3968
                 URL: https://issues.apache.org/jira/browse/CALCITE-3968
             Project: Calcite
          Issue Type: Improvement
          Components: core
            Reporter: Haisheng Yuan


JoinPushThroughJoinRule.right does 
(RS)T -> (RT)S

JoinPushThroughJoinRule.left does
(RS)T -> (TS)R 

If JoinCommuteRule is enabled, only enabling JoinPushThroughJoinRule.right can 
achieve the same alternative with JoinPushThroughJoinRule.left, vice versa 
(suppose they are connected). So there is no need to enable left and right 
instances at the same time, which will slow down the optimization dramatically, 
e.g TPCH q05, q07 in TpchTest.java never finish. There is also the same bug 
report from [1].

Meanwhile, JoinPushThroughJoinRule matches RelNode.class, which is unnecessary. 
It should be just a group, or RelSet / RelSubset, as a place holder, because we 
don't care about what exactly the top join's right child is. But since the rule 
is designed to work with both HepPlanner and VolcanoPlanner, so just bear with 
the slowness.

[1] 
https://lists.apache.org/thread.html/r195c267ef15f50aa21bbcefd7bf523f8bf2495b2345fd163e91e3c36%40%3Cdev.calcite.apache.org%3E



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