alamb commented on code in PR #13736:
URL: https://github.com/apache/datafusion/pull/13736#discussion_r1885708573
##########
datafusion/physical-expr-common/src/physical_expr.rs:
##########
@@ -149,6 +151,11 @@ pub trait PhysicalExpr: Send + Sync + Display + Debug +
DynEq + DynHash {
fn get_properties(&self, _children: &[ExprProperties]) ->
Result<ExprProperties> {
Ok(ExprProperties::new_unknown())
}
+
+ /// Return the column statistics of this expression given the statistics
of the input
Review Comment:
This API seems somewhat overlapping with
[`PhysicalExpr::evaluate_bounds`](https://docs.rs/datafusion/latest/datafusion/physical_expr/trait.PhysicalExpr.html#method.evaluate_bounds)
I wonder if there is any way to combine the ideas with the `Statistics`
changes @suremarc is looking into in
https://github.com/apache/datafusion/pull/13293#issuecomment-2540053084 🤔
##########
datafusion/functions-aggregate/src/average.rs:
##########
@@ -253,6 +254,34 @@ impl AggregateUDFImpl for Avg {
coerce_avg_type(self.name(), arg_types)
}
+ fn value_from_stats(&self, statistics_args: &StatisticsArgs) ->
Option<ScalarValue> {
+ if statistics_args.is_distinct {
+ return None;
+ }
+
+ if let Precision::Exact(num_rows) =
&statistics_args.statistics.num_rows {
Review Comment:
this is a very neat idea
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