feat(expr): allow explicit cast serial to bigint

Signed-off-by: TennyZhuang <[email protected]>

src/common/src/types/serial.rs

@@ -26,6 +26,12 @@ use crate::util::row_id::RowId;
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Ord, PartialOrd, Default, Hash)]
 pub struct Serial(i64);
 
+impl From<Serial> for i64 {
+    fn from(value: Serial) -> i64 {
+        value.0
+    }
+}
+
 impl From<i64> for Serial {
     fn from(value: i64) -> Self {
         Self(value)

src/expr/impl/src/scalar/cast.rs

@@ -87,6 +87,7 @@ pub fn jsonb_to_number<T: TryFrom<F64>>(v: JsonbRef<'_>) -> Result<T> {
 #[function("cast(int4) -> int2")]
 #[function("cast(int8) -> int2")]
 #[function("cast(int8) -> int4")]
+#[function("cast(serial) -> int8")]
 #[function("cast(float4) -> int2")]
 #[function("cast(float8) -> int2")]
 #[function("cast(float4) -> int4")]

src/frontend/src/expr/type_inference/cast.rs

@@ -216,22 +216,23 @@ pub static CAST_MAP: LazyLock<CastMap> = LazyLock::new(|| {
     use DataTypeName::*;
     const CAST_TABLE: &[(&str, DataTypeName)] = &[
         // 123456789ABCDEF
-        (". e            a", Boolean),     // 0
-        (" .iiiiii       a", Int16),       // 1
-        ("ea.iiiii       a", Int32),       // 2
-        (" aa.iiii       a", Int64),       // 3
-        (" aaa.ii        a", Decimal),     // 4
-        (" aaaa.i        a", Float32),     // 5
-        (" aaaaa.        a", Float64),     // 6
-        ("      e.       a", Int256),      // 7
-        ("        .ii    a", Date),        // 8
-        ("        a.ia   a", Timestamp),   // 9
-        ("        aa.a   a", Timestamptz), // A
-        ("           .i  a", Time),        // B
-        ("           a.  a", Interval),    // C
-        ("eeeeeee      . a", Jsonb),       // D
-        ("              .a", Bytea),       // E
-        ("eeeeeeeeeeeeeee.", Varchar),     // F
+        (". e            a ", Boolean),     // 0
+        (" .iiiiii       a ", Int16),       // 1
+        ("ea.iiiii       a ", Int32),       // 2
+        (" aa.iiii       a ", Int64),       // 3
+        (" aaa.ii        a ", Decimal),     // 4
+        (" aaaa.i        a ", Float32),     // 5
+        (" aaaaa.        a ", Float64),     // 6
+        ("      e.       a ", Int256),      // 7
+        ("        .ii    a ", Date),        // 8
+        ("        a.ia   a ", Timestamp),   // 9
+        ("        aa.a   a ", Timestamptz), // A
+        ("           .i  a ", Time),        // B
+        ("           a.  a ", Interval),    // C
+        ("eeeeeee      . a ", Jsonb),       // D
+        ("              .a ", Bytea),       // E
+        ("eeeeeeeeeeeeeee. ", Varchar),     // F
+        ("   e            .", Serial),
     ];
     let mut map = BTreeMap::new();
     for (row, source) in CAST_TABLE {