jayzhan211 commented on code in PR #14927:
URL: https://github.com/apache/datafusion/pull/14927#discussion_r1978403578
##########
datafusion/functions-aggregate/src/count.rs:
##########
@@ -80,8 +83,32 @@ pub fn count_distinct(expr: Expr) -> Expr {
}
/// Creates aggregation to count all rows, equivalent to `COUNT(*)`,
`COUNT()`, `COUNT(1)`
+/// Alias to count(*) for backward comaptibility
pub fn count_all() -> Expr {
- count(Expr::Literal(COUNT_STAR_EXPANSION))
+ count(Expr::Literal(COUNT_STAR_EXPANSION)).alias("count(*)")
+}
+
+/// Creates window aggregation to count all rows, equivalent to `COUNT(*)`,
`COUNT()`, `COUNT(1)`
+pub fn count_all_window() -> Expr {
+ Expr::WindowFunction(WindowFunction::new(
+ WindowFunctionDefinition::AggregateUDF(count_udaf()),
+ vec![Expr::Literal(COUNT_STAR_EXPANSION)],
+ ))
+}
+
+/// Create count wildcard window func of Expr::Column
+pub fn count_all_window_column() -> Expr {
+ col(Expr::WindowFunction(WindowFunction::new(
+ WindowFunctionDefinition::AggregateUDF(count_udaf()),
+ vec![Expr::Literal(COUNT_STAR_EXPANSION)],
+ ))
+ .schema_name()
+ .to_string())
+}
+
+/// Create count wildcard of Expr::Column
Review Comment:
One of the example is been used in
`test_count_wildcard_on_where_scalar_subquery`
```rust
let df_results = ctx
.table("t1")
.await?
.filter(
scalar_subquery(Arc::new(
ctx.table("t2")
.await?
.filter(out_ref_col(DataType::UInt32,
"t1.a").eq(col("t2.a")))?
.aggregate(vec![], vec![count_all()])?
.select(vec![count_all_column()])?
.into_unoptimized_plan(),
))
.gt(lit(ScalarValue::UInt8(Some(0)))),
)?
.select(vec![col("t1.a"), col("t1.b")])?
.explain(false, false)?
.collect()
.await?;
```
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