[DISCUSS] Deprecate TableScanRule

[Danny Chan <yu...@gmail.com>]

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

Best,
Danny Chan

Re: [DISCUSS] Deprecate TableScanRule

[Julian Hyde <jh...@apache.org>]

Discussion moved to https://issues.apache.org/jira/browse/CALCITE-3769 <https://issues.apache.org/jira/browse/CALCITE-3769>.  (For the benefit of those reading the archive.)

> On Feb 4, 2020, at 3:25 AM, Danny Chan <yu...@gmail.com> wrote:
> 
> 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
> 
> Best,
> Danny Chan