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https://issues.apache.org/jira/browse/CALCITE-1499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15685176#comment-15685176
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Julian Hyde commented on CALCITE-1499:
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Makes sense. I haven't checked the code, but is it possible to do this by
adding an extra step to a {{Program}}? Or perhaps extending the Program API a
little. I would love to be able to accomplish these kind of things without
changing the planner engine.
> Add an option to exclude VolcanoPlanner's "originalRoot" from planning process
> ------------------------------------------------------------------------------
>
> Key: CALCITE-1499
> URL: https://issues.apache.org/jira/browse/CALCITE-1499
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.10.0
> Reporter: Maryann Xue
> Assignee: Maryann Xue
>
> The Calcite compilation framework runs a series of Programs for query
> planning. The default programs consist of some pre-processing HepPrograms,
> e.g., de-correlation, field-trimming, etc., the volcano planning program,
> and some post-processing HepPrograms. In {{Prepare.optimize()}},
> {{planner.setRoot()}} is called before running the programs. As a result, the
> original rel from sql-to-rel conversion becomes the "originalRoot" in the
> VolcanoPlanner, and the new rel from the pre-processing programs becomes the
> new "root". In some cases, we would only want to run volcano planning on the
> new root based on the assumption that the new root is the desired form after
> pre-processing. And if we have an option to turn off the planning of the
> original root, the planning space can be significantly reduced.
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