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
