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https://issues.apache.org/jira/browse/CALCITE-7093?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18007611#comment-18007611
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Mihai Budiu commented on CALCITE-7093:
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The question is whether you can switch the metadata provider just for this
optimization. You could use a different CumulativeCost model for the Volcano
planner and for this optimization. For example, I have experimented with a cost
model where the cost is the depth of the plan (counted in operators). Using
this cost model for this algorithm allows it to behave like the bushy join
optimization (which does not handle outer joins at all). But this cost model
may not be useful for other optimizations you may be doing.
> DPhyp algorithm should accept cost model as parameter
> -----------------------------------------------------
>
> Key: CALCITE-7093
> URL: https://issues.apache.org/jira/browse/CALCITE-7093
> Project: Calcite
> Issue Type: Wish
> Components: core
> Affects Versions: 1.40.0
> Reporter: Mihai Budiu
> Priority: Minor
>
> This is about the hypergraph-based optimization introduced in [CALCITE-6846]
> by [~dongsl].
> The algorithm makes calls to a cost model using getCumulativeCost() (function
> chooseBetterPlan()); the cost model is obtained from the Rel nodes.
> It could be useful to allow add to the the rule configuration an API to
> specify a cost model, similar to the MULTI_JOIN_OPTIMIZE rule
> (LoptOptimizeJoinRule), whose Config has as "withCostFunction" api.
> For example, this would allow the algorithm to emulate bushy join
> optimization using a cost model that optimizes for plan depth.
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