adriangb commented on code in PR #20091:
URL: https://github.com/apache/datafusion/pull/20091#discussion_r2749770625
##########
datafusion/expr/src/logical_plan/plan.rs:
##########
@@ -2807,14 +2829,129 @@ impl TableScan {
Ok(Self {
table_name,
source: table_source,
- projection,
+ projection: projection_exprs,
projected_schema,
filters,
fetch,
})
}
}
+/// Builder for creating `TableScan` nodes with expression-based projections.
+///
+/// This builder provides a flexible way to construct `TableScan` nodes,
+/// particularly when working with expression-based projections directly.
+#[derive(Clone)]
+pub struct TableScanBuilder {
Review Comment:
This is a bit of refactor that while not strictly necessary for this PR I
think will be helpful for future (and makes the code in this PR nicer).
##########
datafusion/expr/src/utils.rs:
##########
@@ -1286,6 +1286,36 @@ pub fn format_state_name(name: &str, state_name: &str)
-> String {
format!("{name}[{state_name}]")
}
+/// Convert projection expressions (assumed to be column references) to column
indices.
+///
+/// This function takes a list of expressions (which should be `Expr::Column`
variants)
+/// and returns the indices of those columns in the given schema. Returns
`None` if
+/// any expression is not a simple column reference, or if the column is not
found
+/// in the schema.
+///
+/// # Arguments
+/// * `exprs` - A slice of expressions, expected to be `Expr::Column` variants
+/// * `schema` - The schema to look up column indices in
+///
+/// # Returns
+/// * `Some(Vec<usize>)` - If all expressions are column references found in
the schema
+/// * `None` - If any expression is not a column reference or not found in
schema
+pub fn projection_indices_from_exprs(
Review Comment:
I'm not super sold on this function. I feel there is a footgun where you
don't know if `None` means complex expressions (maybe you forgot to check for
them?) or if `None` means a column was not found in the schema (also something
that maybe should never happen?).
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