Removes min/max/count comparison based on name in aggregate statistics

Author: edmondop

datafusion/expr/src/udaf.rs

@@ -262,6 +262,19 @@ impl AggregateUDF {
         self.inner.is_descending()
     }
 
+    /// Returns true if the function is min. Used by the optimizer
+    pub fn is_min(&self) -> bool {
+        self.inner.is_min()
+    }
+
+    /// Returns true if the function is max. Used by the optimizer
+    pub fn is_max(&self) -> bool {
+        self.inner.is_max()
+    }
+    /// Returns true if the function is count. Used by the optimizer
+    pub fn is_count(&self) -> bool {
+        self.inner.is_count()
+    }
     /// See [`AggregateUDFImpl::default_value`] for more details.
     pub fn default_value(&self, data_type: &DataType) -> Result<ScalarValue> {
         self.inner.default_value(data_type)
@@ -575,6 +588,19 @@ pub trait AggregateUDFImpl: Debug + Send + Sync {
         None
     }
 
+    // Returns true if the function is min. Used by the optimizer
+    fn is_min(&self) -> bool {
+        false
+    }
+    // Returns true if the function is max. Used by the optimizer
+    fn is_max(&self) -> bool {
+        false
+    }
+    // Returns true if the function is count. Used by the optimizer
+    fn is_count(&self) -> bool {
+        false
+    }
+
     /// Returns default value of the function given the input is all `null`.
     ///
     /// Most of the aggregate function return Null if input is Null,

datafusion/functions-aggregate/src/count.rs

@@ -291,6 +291,10 @@ impl AggregateUDFImpl for Count {
     fn default_value(&self, _data_type: &DataType) -> Result<ScalarValue> {
         Ok(ScalarValue::Int64(Some(0)))
     }
+
+    fn is_count(&self) -> bool {
+        true
+    }
 }
 
 #[derive(Debug)]

datafusion/functions-aggregate/src/min_max.rs

@@ -272,6 +272,10 @@ impl AggregateUDFImpl for Max {
     fn is_descending(&self) -> Option<bool> {
         Some(true)
     }
+
+    fn is_max(&self) -> bool {
+        true
+    }
     fn order_sensitivity(&self) -> datafusion_expr::utils::AggregateOrderSensitivity {
         datafusion_expr::utils::AggregateOrderSensitivity::Insensitive
     }
@@ -1052,6 +1056,10 @@ impl AggregateUDFImpl for Min {
         Some(false)
     }
 
+    fn is_min(&self) -> bool {
+        true
+    }
+
     fn order_sensitivity(&self) -> datafusion_expr::utils::AggregateOrderSensitivity {
         datafusion_expr::utils::AggregateOrderSensitivity::Insensitive
     }

datafusion/physical-optimizer/src/aggregate_statistics.rs

@@ -181,7 +181,7 @@ fn take_optimizable_min(
         match *num_rows {
             0 => {
                 // MIN/MAX with 0 rows is always null
-                if is_min(agg_expr) {
+                if agg_expr.fun().is_min() {
                     if let Ok(min_data_type) =
                         ScalarValue::try_from(agg_expr.field().data_type())
                     {
@@ -191,7 +191,7 @@ fn take_optimizable_min(
             }
             value if value > 0 => {
                 let col_stats = &stats.column_statistics;
-                if is_min(agg_expr) {
+                if agg_expr.fun().is_min() {
                     let exprs = agg_expr.expressions();
                     if exprs.len() == 1 {
                         // TODO optimize with exprs other than Column
@@ -227,7 +227,7 @@ fn take_optimizable_max(
         match *num_rows {
             0 => {
                 // MIN/MAX with 0 rows is always null
-                if is_max(agg_expr) {
+                if agg_expr.fun().is_max() {
                     if let Ok(max_data_type) =
                         ScalarValue::try_from(agg_expr.field().data_type())
                     {
@@ -237,7 +237,7 @@ fn take_optimizable_max(
             }
             value if value > 0 => {
                 let col_stats = &stats.column_statistics;
-                if is_max(agg_expr) {
+                if agg_expr.fun().is_max() {
                     let exprs = agg_expr.expressions();
                     if exprs.len() == 1 {
                         // TODO optimize with exprs other than Column
@@ -273,22 +273,4 @@ fn is_non_distinct_count(agg_expr: &AggregateFunctionExpr) -> bool {
     false
 }
 
-// TODO: Move this check into AggregateUDFImpl
-// https://github.com/apache/datafusion/issues/11153
-fn is_min(agg_expr: &AggregateFunctionExpr) -> bool {
-    if agg_expr.fun().name().to_lowercase() == "min" {
-        return true;
-    }
-    false
-}
-
-// TODO: Move this check into AggregateUDFImpl
-// https://github.com/apache/datafusion/issues/11153
-fn is_max(agg_expr: &AggregateFunctionExpr) -> bool {
-    if agg_expr.fun().name().to_lowercase() == "max" {
-        return true;
-    }
-    false
-}
-
 // See tests in datafusion/core/tests/physical_optimizer