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Hive, mail # dev - Review Request 18172: HIVE-6439 Introduce CBO step in Semantic Analyzer


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Re: Review Request 18172: HIVE-6439 Introduce CBO step in Semantic Analyzer
John Pullokkaran 2014-02-17, 07:18

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https://reviews.apache.org/r/18172/#review34624
1. In most query engines 20 way joins and beyond is hard to reorder. So i would imagine that we would need a similar flag(hive.cbo.max.joins.supported) to control the length of join graph that is being considered for reordering.
2. Its reasonable to introduce ql.optimizer.CostBasedOptimizer which then calls in to Optiq based Optimizer.
   One thing to keep in mind, Optiq based optimizer would have both rule based and cost based portions.

- John Pullokkaran
On Feb. 17, 2014, 6:49 a.m., Harish Butani wrote: