alamb commented on code in PR #9690:
URL: https://github.com/apache/arrow-datafusion/pull/9690#discussion_r1535986457
##########
datafusion/optimizer/src/optimize_projections.rs:
##########
@@ -162,14 +163,37 @@ fn optimize_projections(
.map(|input|
((0..input.schema().fields().len()).collect_vec(), false))
.collect::<Vec<_>>()
}
+ LogicalPlan::Extension(extension) => {
+ let children = extension.node.inputs();
+ if children.len() != 1 {
+ // TODO: Add support for `LogicalPlan::Extension` with multi
children.
+ return Ok(None);
+ }
+ // has single child
+ let exprs = plan.expressions();
+ let child = children[0];
+ let node_schema = extension.node.schema();
+ let child_schema = child.schema();
+ if let Some(parent_required_indices_mapped) =
Review Comment:
> Which would produce following invalid plan:
That is a good point.
> What about an API something like
That is a great idea, though I don't fully understand why it uses `Expr`s
How about a slight refinement in terms of input/output columns:
```rust
/// Returns the necessary input columns to this node required to compute
/// the columns in the output schema
///
/// This is used for projection pushdown when DataFusion has determined that
/// only a subset of the output columns of this node are needed by its
parents.
/// This API is used to tell DataFusion which, if any, of the input columns
are no longer
/// needed.
///
/// Return `Ok(None)`, the default, if this information can not be determined
/// Returns `Ok(input_columns)` with the column indexes from this nodes'
input that are
/// needed to compute `output_columns`)
fn necessary_children_exprs(&self, output_columns: &[usize]) ->
Option<Vec<usize>> {
Ok(None)
}
```
🤔
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