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https://issues.apache.org/jira/browse/CALCITE-6788?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Claude Brisson updated CALCITE-6788:
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Description:
{{LoptOptimizeJoinRule}} uses costs comparisons to recursively decide whether
to add a join at the top of the joins tree or to push it down.
When doing so, instead of directly calling {{mq.getCumulativeCost(rel)}}, it
should rely on {{call.getPlanner.getCost(rel, mq)}}, which will be used
thereafter to choose the best joins tree.
This way, it becomes possible to customize the costs computation during the
heuristic joins ordering phase by just overriding the {{getCost()}} method of
the optimization planner.
Without this patch, it is only possible to alter joins costs at the final phase
of the algorithm, which defeats the goal of customizing them, including during
the to-top/push-down phase.
was:
{{LoptOptimizeJoinRule}} uses costs comparisons to recursively decide whether
to add a join at the top of the joins tree or to push it down.
When doing so, instead of directly calling {{mq.getCumulativeCost(rel)}}, it
should rely on {{call.getPlanner.getCost(rel, mq)}}, which will be used
thereafter to choose the best joins tree.
This way, it becomes possible to customize the costs computation during the
heuristic joins ordering phase by just altering the {{getCost()}} method of the
optimization planner.
Without this patch, it is only possible to alter joins costs at the final phase
of the algorithm, which defeats the goal of customizing them, including during
the to-top/push-down phase.
> LoptOptimizeJoinRule should delegate costs to optimization planner
> ------------------------------------------------------------------
>
> Key: CALCITE-6788
> URL: https://issues.apache.org/jira/browse/CALCITE-6788
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.38.0
> Reporter: Claude Brisson
> Priority: Major
> Labels: pull-request-available
>
> {{LoptOptimizeJoinRule}} uses costs comparisons to recursively decide whether
> to add a join at the top of the joins tree or to push it down.
> When doing so, instead of directly calling {{mq.getCumulativeCost(rel)}}, it
> should rely on {{call.getPlanner.getCost(rel, mq)}}, which will be used
> thereafter to choose the best joins tree.
> This way, it becomes possible to customize the costs computation during the
> heuristic joins ordering phase by just overriding the {{getCost()}} method of
> the optimization planner.
> Without this patch, it is only possible to alter joins costs at the final
> phase of the algorithm, which defeats the goal of customizing them, including
> during the to-top/push-down phase.
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