More correct

Author: levkk

pgdog/src/backend/pool/connection/aggregate.rs

@@ -46,14 +46,6 @@ impl<'a> Accumulator<'a> {
                     target,
                     datum: Datum::Bigint(0),
                 },
-                AggregateFunction::Max => Accumulator {
-                    target,
-                    datum: Datum::Bigint(i64::MIN),
-                },
-                AggregateFunction::Min => Accumulator {
-                    target,
-                    datum: Datum::Bigint(i64::MAX),
-                },
                 _ => Accumulator {
                     target,
                     datum: Datum::Null,
@@ -68,12 +60,20 @@ impl<'a> Accumulator<'a> {
             match self.target.function() {
                 AggregateFunction::Count => self.datum = self.datum.clone() + column.value,
                 AggregateFunction::Max => {
-                    if self.datum < column.value {
+                    if !self.datum.is_null() {
+                        if self.datum < column.value {
+                            self.datum = column.value;
+                        }
+                    } else {
                         self.datum = column.value;
                     }
                 }
                 AggregateFunction::Min => {
-                    if self.datum > column.value {
+                    if !self.datum.is_null() {
+                        if self.datum > column.value {
+                            self.datum = column.value;
+                        }
+                    } else {
                         self.datum = column.value;
                     }
                 }

pgdog/src/net/messages/data_types/mod.rs

@@ -78,6 +78,8 @@ impl Add for Datum {
             (SmallInt(a), SmallInt(b)) => SmallInt(a + b),
             (Interval(a), Interval(b)) => Interval(a + b),
             (Numeric(a), Numeric(b)) => Numeric(a + b),
+            (Datum::Null, b) => b,
+            (a, Datum::Null) => a,
             _ => Datum::Null, // Might be good to raise an error.
         }
     }
@@ -103,6 +105,10 @@ impl Datum {
             _ => Ok(Datum::Null),
         }
     }
+
+    pub fn is_null(&self) -> bool {
+        matches!(self, Datum::Null)
+    }
 }
 
 /// PostgreSQL data types.