diff --git a/datafusion/expr-common/src/signature.rs b/datafusion/expr-common/src/signature.rs
index dee8fc618354..f2cde4527f0c 100644
--- a/datafusion/expr-common/src/signature.rs
+++ b/datafusion/expr-common/src/signature.rs
@@ -156,7 +156,7 @@ impl TypeSignature {
     }
 }
 
-#[derive(Debug, Clone, Eq, PartialOrd)]
+#[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Hash)]
 pub enum TypeSignatureClass {
     Timestamp,
     Date,
@@ -169,22 +169,6 @@ pub enum TypeSignatureClass {
     Native(LogicalTypeRef),
 }
 
-// TODO: MSRV issue: Default macro doesn't work in 1.79. Use default PartialEq macro after it is able to compile
-impl PartialEq for TypeSignatureClass {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Self::Native(l0), Self::Native(r0)) => l0 == r0,
-            _ => core::mem::discriminant(self) == core::mem::discriminant(other),
-        }
-    }
-}
-
-impl std::hash::Hash for TypeSignatureClass {
-    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
-        core::mem::discriminant(self).hash(state);
-    }
-}
-
 impl Display for TypeSignatureClass {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(f, "TypeSignatureClass::{self:?}")
diff --git a/datafusion/sqllogictest/test_files/expr.slt b/datafusion/sqllogictest/test_files/expr.slt
index f7902af5d4b3..2a8ce39738c8 100644
--- a/datafusion/sqllogictest/test_files/expr.slt
+++ b/datafusion/sqllogictest/test_files/expr.slt
@@ -1109,15 +1109,10 @@ SELECT date_part('second', timestamp '2020-09-08T12:00:12.12345678+00:00')
 ----
 12
 
-query I
-SELECT date_part('millisecond', timestamp '2020-09-08T12:00:12.12345678+00:00')
-----
-12
-
 query I
 SELECT date_part('microsecond', timestamp '2020-09-08T12:00:12.12345678+00:00')
 ----
-12123
+12123456
 
 query error DataFusion error: Internal error: unit Nanosecond not supported
 SELECT date_part('nanosecond', timestamp '2020-09-08T12:00:12.12345678+00:00')
diff --git a/datafusion/sqllogictest/test_files/group_by.slt b/datafusion/sqllogictest/test_files/group_by.slt
index fc09b5242141..df7e21c2da44 100644
--- a/datafusion/sqllogictest/test_files/group_by.slt
+++ b/datafusion/sqllogictest/test_files/group_by.slt
@@ -4281,7 +4281,7 @@ EXPLAIN SELECT extract(month from ts) as months
 logical_plan
 01)Sort: months DESC NULLS FIRST, fetch=5
 02)--Projection: date_part(Utf8("MONTH"),csv_with_timestamps.ts) AS months
-03)----Aggregate: groupBy=[[date_part(Utf8View("MONTH"), csv_with_timestamps.ts) AS date_part(Utf8("MONTH"),csv_with_timestamps.ts)]], aggr=[[]]
+03)----Aggregate: groupBy=[[date_part(Utf8("MONTH"), csv_with_timestamps.ts)]], aggr=[[]]
 04)------TableScan: csv_with_timestamps projection=[ts]
 physical_plan
 01)SortPreservingMergeExec: [months@0 DESC], fetch=5