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https://issues.apache.org/jira/browse/CALCITE-3769?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17030304#comment-17030304
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Julian Hyde commented on CALCITE-3769:
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An alternative is to deprecate {{toRel}}.
(I really don’t know which I prefer. But let’s consider both.)
{{ToRelContext}} is difficult to understand, and poorly named. Before we add it
to the {{RelBuilder}} API it needs to be better designed.
> Deprecate TableScanRule
> -----------------------
>
> Key: CALCITE-3769
> URL: https://issues.apache.org/jira/browse/CALCITE-3769
> Project: Calcite
> Issue Type: Wish
> Components: core
> Affects Versions: 1.21.0
> Reporter: Danny Chen
> Assignee: Danny Chen
> Priority: Major
> Fix For: 1.22.0
>
>
> The TableScanRule is the only planner rule that for a logical node(e.g. the
> table scan), it’s functionality is to pass along the cluster object and
> invoke the RelOptTable#toRel. It’s function is very trivial because it
> supplies only a ToRelContext that does not support expanding view/passing
> table hints.
> For rels that come from the sql-to-rel conversion, there is already a table
> conversion logic[1]. This code gives a powerful
> ToRelContext that has the complete functionality.
> The only reason that I saw the meaning of existing TableScanRule is for the
> TableScan that comes from the RelBuilder#scan.
> So I would suggest to deprecate the TableScanRule, instead, we support
> translating the table directly in RelBuilder#scan,
> We also add a new interface RelBuilder#scan(Iterable<String> tableNames,
> ToRelContext context), so that we can pass in a more powerful ToRelContext
> explicitly.
> [1]
> https://github.com/apache/calcite/blob/d6fa25cd11625ad7b4b74dafbd0211c701b38d49/core/src/main/java/org/apache/calcite/sql2rel/SqlToRelConverter.java#L3498
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