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From Yuzhao Chen <yuzhao....@gmail.com>
Subject Re: ClassCastException RelOptCostImpl VolcanoCost while using HepPlanner
Date Thu, 02 May 2019 01:15:16 GMT
Why you care about cost when use HepPlanner ? The HepPlanner is aimed for some deterministic
planning rules, we usually do not need cost in Hep. Some exceptions like Join reorder may
need a cost.

What kind of planning promotion you did ? I'm kind of curious about it.

Best,
Danny Chan
在 2019年5月1日 +0800 PM9:27,Mark Pasterkamp <markpasterkamp1994@gmail.com>,写道:
> Dear all,
>
> While playing around with the HepPlanner I ran into an issue where the
> planner wants to rewrite a query with a union rewrite. When the
> RelMetaDataQuery computes the cost, the cost instance is a VolcanoCost.
> Then when it tries to calculate the cost of one of the union's operands it
> is a RelCostImpl which results in the ClassCastException.
>
> How would I go about solving this issue? As far as my knowledge goes, I am
> not able to change the costhandler of the RelMetaDataQuery. Another
> approach I could see is removing the cast in the VolcanoCost class, but I
> would hope I do not have to do that.
>
>
> With kind regards,
>
> Mark

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