refactor(DataType): cleanup outdated helpers (#7685)

The following 2 helpers are no longer used in any place: `is_type_encodable`, `mem_cmp_eq_value_enc`.

Note: right now all DataTypes are encodable in memcomparable format. We will reintroduce the difference and disallow certain types from being used as memcomparable later.

Approved-By: liurenjie1024

src/common/src/types/mod.rs

@@ -342,18 +342,6 @@ impl DataType {
         }
     }
 
-    /// Checks if memcomparable encoding of datatype is equivalent to its value encoding.
-    pub fn mem_cmp_eq_value_enc(&self) -> bool {
-        use DataType::*;
-        match self {
-            Boolean | Int16 | Int32 | Int64 => true,
-            Float32 | Float64 | Decimal | Date | Varchar | Time | Timestamp | Timestamptz
-            | Interval | Bytea => false,
-            Struct(t) => t.fields.iter().all(|dt| dt.mem_cmp_eq_value_enc()),
-            List { datatype } => datatype.mem_cmp_eq_value_enc(),
-        }
-    }
-
     pub fn new_struct(fields: Vec<DataType>, field_names: Vec<String>) -> Self {
         Self::Struct(
             StructType {

src/common/src/util/encoding_for_comparison.rs

@@ -17,24 +17,9 @@ use itertools::Itertools;
 use crate::array::{ArrayImpl, DataChunk};
 use crate::error::Result;
 use crate::row::OwnedRow;
-use crate::types::{memcmp_serialize_datum_into, DataType, ScalarRefImpl};
+use crate::types::{memcmp_serialize_datum_into, ScalarRefImpl};
 use crate::util::sort_util::{OrderPair, OrderType};
 
-/// This function is used to check whether we can perform encoding on this type.
-/// TODO: based on `memcomparable`, we may support more data type in the future.
-pub fn is_type_encodable(t: DataType) -> bool {
-    matches!(
-        t,
-        DataType::Boolean
-            | DataType::Int16
-            | DataType::Int32
-            | DataType::Int64
-            | DataType::Float32
-            | DataType::Float64
-            | DataType::Varchar
-    )
-}
-
 fn encode_value(value: Option<ScalarRefImpl<'_>>, order: &OrderType) -> Result<Vec<u8>> {
     let mut serializer = memcomparable::Serializer::new(vec![]);
     serializer.set_reverse(order == &OrderType::Descending);