gene-bordegaray commented on code in PR #24670:
URL: https://github.com/apache/datafusion/pull/24670#discussion_r3927677162
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datafusion/physical-plan/src/projection.rs:
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@@ -270,6 +278,33 @@ impl ProjectionExec {
))
}
+ /// Returns whether `projector`'s output metadata differs from the metadata
+ /// derived from its expressions and `input_schema`.
+ fn compute_overrides_metadata(
+ projector: &Projector,
+ input_schema: &Schema,
+ ) -> Result<bool> {
+ let output_schema = projector.output_schema();
+ if input_schema.metadata() != output_schema.metadata() {
+ return Ok(true);
+ }
+ for (projection, output_field) in
+ projector.projection().iter().zip(output_schema.fields())
+ {
+ let derived_field = projection.expr.return_field(input_schema)?;
+ if derived_field.metadata() != output_field.metadata() {
+ return Ok(true);
+ }
+ }
+ Ok(false)
Review Comment:
yes we could. The only thing is `project_schema` does a ton of extra stuff
we don't really need. So with the past wide schema perf concerns I think just
deriving exactly what we need is gonna give us better perf here
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