alamb commented on a change in pull request #1506:
URL: https://github.com/apache/arrow-datafusion/pull/1506#discussion_r777023721
##########
File path: datafusion/src/logical_plan/expr.rs
##########
@@ -1317,6 +1318,79 @@ pub fn normalize_cols(
.collect()
}
+/// Rewrite sort on aggregate expressions to sort on the column of aggregate
output
+pub fn rewrite_sort_cols_by_aggs(
+ exprs: impl IntoIterator<Item = impl Into<Expr>>,
+ plan: &LogicalPlan,
+) -> Result<Vec<Expr>> {
+ exprs
+ .into_iter()
+ .map(|e| {
+ let expr = e.into();
+ match expr.clone() {
+ Expr::Sort {
+ expr,
+ asc,
+ nulls_first,
+ } => {
+ let sort = Expr::Sort {
+ expr: Box::new(rewrite_sort_col_by_aggs(*expr, plan)?),
+ asc,
+ nulls_first,
+ };
+ Ok(sort)
+ }
+ _ => Ok(expr),
Review comment:
I think you can avoid this clone via:
```suggestion
match expr {
Expr::Sort {
expr,
asc,
nulls_first,
} => {
let sort = Expr::Sort {
expr: Box::new(rewrite_sort_col_by_aggs(*expr,
plan)?),
asc,
nulls_first,
};
Ok(sort)
}
expr => Ok(expr),
```
##########
File path: datafusion/tests/sql/order.rs
##########
@@ -32,6 +32,27 @@ async fn test_sort_unprojected_col() -> Result<()> {
Ok(())
}
+#[tokio::test]
+async fn test_order_by_agg_expr() -> Result<()> {
+ let mut ctx = ExecutionContext::new();
+ register_aggregate_csv(&mut ctx).await?;
+ let sql = "SELECT MIN(c12) FROM aggregate_test_100 ORDER BY MIN(c12)";
+ let actual = execute_to_batches(&mut ctx, sql).await;
+ let expected = vec![
+ "+-----------------------------+",
+ "| MIN(aggregate_test_100.c12) |",
+ "+-----------------------------+",
+ "| 0.01479305307777301 |",
+ "+-----------------------------+",
+ ];
+ assert_batches_eq!(expected, &actual);
+
+ let sql = "SELECT MIN(c12) FROM aggregate_test_100 ORDER BY MIN(c12) +
0.1";
Review comment:
👍
##########
File path: datafusion/src/logical_plan/expr.rs
##########
@@ -1317,6 +1318,79 @@ pub fn normalize_cols(
.collect()
}
+/// Rewrite sort on aggregate expressions to sort on the column of aggregate
output
+pub fn rewrite_sort_cols_by_aggs(
+ exprs: impl IntoIterator<Item = impl Into<Expr>>,
+ plan: &LogicalPlan,
+) -> Result<Vec<Expr>> {
+ exprs
+ .into_iter()
+ .map(|e| {
+ let expr = e.into();
+ match expr.clone() {
+ Expr::Sort {
+ expr,
+ asc,
+ nulls_first,
+ } => {
+ let sort = Expr::Sort {
+ expr: Box::new(rewrite_sort_col_by_aggs(*expr, plan)?),
+ asc,
+ nulls_first,
+ };
+ Ok(sort)
+ }
+ _ => Ok(expr),
+ }
+ })
+ .collect()
+}
+
+fn rewrite_sort_col_by_aggs(expr: Expr, plan: &LogicalPlan) -> Result<Expr> {
+ match plan {
+ LogicalPlan::Aggregate(Aggregate {
+ input, aggr_expr, ..
+ }) => {
+ struct Rewriter<'a> {
+ plan: &'a LogicalPlan,
+ input: &'a LogicalPlan,
+ aggr_expr: &'a Vec<Expr>,
+ }
+
+ impl<'a> ExprRewriter for Rewriter<'a> {
+ fn mutate(&mut self, expr: Expr) -> Result<Expr> {
+ let normalized_expr = normalize_col(expr.clone(),
self.plan);
+ if normalized_expr.is_err() {
+ // The expr is not based on Aggregate plan output.
Skip it.
+ return Ok(expr);
+ }
+ let normalized_expr = normalized_expr.unwrap();
+ let found_agg =
+ self.aggr_expr.iter().find(|a| (**a) ==
normalized_expr);
+ if found_agg.is_some() {
+ let agg = normalize_col(found_agg.unwrap().clone(),
self.plan)?;
+ let col = Expr::Column(
+ agg.to_field(self.input.schema())
+ .map(|f| f.qualified_column())?,
+ );
+ Ok(col)
+ } else {
+ Ok(expr)
+ }
Review comment:
```suggestion
if let Some(found_agg) = self.aggr_expr.iter().find(|a|
(**a) == normalized_expr) {
let agg = normalize_col(found_agg, self.plan)?;
let col = Expr::Column(
agg.to_field(self.input.schema())
.map(|f| f.qualified_column())?,
);
Ok(col)
} else {
Ok(expr)
}
```
##########
File path: datafusion/src/logical_plan/expr.rs
##########
@@ -1317,6 +1318,79 @@ pub fn normalize_cols(
.collect()
}
+/// Rewrite sort on aggregate expressions to sort on the column of aggregate
output
+pub fn rewrite_sort_cols_by_aggs(
+ exprs: impl IntoIterator<Item = impl Into<Expr>>,
+ plan: &LogicalPlan,
+) -> Result<Vec<Expr>> {
+ exprs
+ .into_iter()
+ .map(|e| {
+ let expr = e.into();
+ match expr.clone() {
+ Expr::Sort {
+ expr,
+ asc,
+ nulls_first,
+ } => {
+ let sort = Expr::Sort {
+ expr: Box::new(rewrite_sort_col_by_aggs(*expr, plan)?),
+ asc,
+ nulls_first,
+ };
+ Ok(sort)
+ }
+ _ => Ok(expr),
+ }
+ })
+ .collect()
+}
+
+fn rewrite_sort_col_by_aggs(expr: Expr, plan: &LogicalPlan) -> Result<Expr> {
+ match plan {
+ LogicalPlan::Aggregate(Aggregate {
+ input, aggr_expr, ..
+ }) => {
+ struct Rewriter<'a> {
+ plan: &'a LogicalPlan,
+ input: &'a LogicalPlan,
+ aggr_expr: &'a Vec<Expr>,
+ }
+
+ impl<'a> ExprRewriter for Rewriter<'a> {
+ fn mutate(&mut self, expr: Expr) -> Result<Expr> {
+ let normalized_expr = normalize_col(expr.clone(),
self.plan);
+ if normalized_expr.is_err() {
+ // The expr is not based on Aggregate plan output.
Skip it.
+ return Ok(expr);
+ }
+ let normalized_expr = normalized_expr.unwrap();
+ let found_agg =
+ self.aggr_expr.iter().find(|a| (**a) ==
normalized_expr);
+ if found_agg.is_some() {
+ let agg = normalize_col(found_agg.unwrap().clone(),
self.plan)?;
+ let col = Expr::Column(
+ agg.to_field(self.input.schema())
+ .map(|f| f.qualified_column())?,
+ );
+ Ok(col)
+ } else {
+ Ok(expr)
+ }
Review comment:
I think you can avoid some `is_some()` and `unwrap()` calls here to make
the code stylistically nicer
##########
File path: datafusion/src/logical_plan/expr.rs
##########
@@ -1317,6 +1318,79 @@ pub fn normalize_cols(
.collect()
}
+/// Rewrite sort on aggregate expressions to sort on the column of aggregate
output
Review comment:
```suggestion
/// Rewrite sort on aggregate expressions to sort on the column of aggregate
output
/// For example, `max(x)` is written to `col("MAX(x)")`
```
It took me a bit of thought to understand what this was doing so I think an
extra comment might help.
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