adriangb commented on PR #15057:
URL: https://github.com/apache/datafusion/pull/15057#issuecomment-2800002196
I would like to resume this work.
Some thoughts should the rewrite happen via a new trait as I'm currently
doing, or should we add a method `PhysicalExpr::with_schema`?
If we add `with_schema` what schema do we pass it? The actual file schema?
There's something to be said for that: it could rewrite filters to case the
literals / filters instead of casting the columns/arrays [as is currently
done](https://github.com/pydantic/datafusion/blob/0b01fdf7f02f9097c319204058576f420b9790b4/datafusion/datasource-parquet/src/row_filter.rs#L146),
which should be cheaper. I expect that any time it was okay to cast the data
it was also okay to cast the predicate itself. It could also absorb the work of
[reassign_predicate_columns](https://github.com/pydantic/datafusion/blob/0b01fdf7f02f9097c319204058576f420b9790b4/datafusion/datasource-parquet/src/row_filter.rs#L123)
(we implement it for `Column` such that if it's index doesn't match but
another one does it swaps).
I suspect the hard bit with this approach will be edge cases: what if a
filter _cannot_ adapt itself to the file schema, but we could cast the column
to make it work? I'm thinking something like a UDF that only accepts `Utf8` but
the the file produces `Utf8View` 🤔
I think @jayzhan-synnada proposed something similar in
https://github.com/apache/datafusion/pull/15685/files#diff-2b3f5563d9441d3303b57e58e804ab07a10d198973eed20e7751b5a20b955e42.
@alamb any thoughts?
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