xiedeyantu commented on code in PR #21362:
URL: https://github.com/apache/datafusion/pull/21362#discussion_r3058052640
##########
datafusion/common/src/functional_dependencies.rs:
##########
@@ -590,6 +590,46 @@ pub fn get_required_group_by_exprs_indices(
.collect()
}
+/// Returns indices for the minimal subset of ORDER BY expressions that are
+/// functionally equivalent to the original set of ORDER BY expressions.
+pub fn get_required_sort_exprs_indices(
+ schema: &DFSchema,
+ sort_expr_names: &[String],
+) -> Option<Vec<usize>> {
+ let dependencies = schema.functional_dependencies();
+ let field_names = schema.field_names();
+ let sort_expr_indices = sort_expr_names
+ .iter()
+ .map(|sort_expr_name| {
+ field_names
+ .iter()
+ .position(|field_name| field_name == sort_expr_name)
+ })
+ .collect::<Option<Vec<_>>>()?;
Review Comment:
it can support simplify `order by deptno, total_sal, abs(deptno)` to `order
by deptno, abs(deptno)` now.
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