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From Mark Pasterkamp <markpasterkamp1...@gmail.com>
Subject Re: ClassCastException RelOptCostImpl VolcanoCost while using HepPlanner
Date Thu, 02 May 2019 05:55:48 GMT
I don't, I would assume that the HepPlanner.findBestExp() calculates the
cost somewhere down the line

On Thu, May 2, 2019, 03:31 Yuzhao Chen <yuzhao.cyz@gmail.com> wrote:

> 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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