optimize cast logic

core/casts/collection.go

@@ -89,7 +89,7 @@ func (pgc *Collection) GetExplicitCast(ctx *sql.Context, sourceType *pgtypes.Dol
 		return c, nil
 	}
 	// We check for the identity and sizing casts after checking the maps, as the identity may be overridden by a user.
-	if cast := pgc.getSizingOrIdentityCast(sourceType, targetType, CastType_Explicit); cast.ID.IsValid() {
+	if cast := pgc.getSizingOrIdentityCast(castID, sourceType, targetType, CastType_Explicit); cast.ID.IsValid() {
 		return cast, nil
 	}
 	// We then check for a record to composite cast
@@ -134,8 +134,8 @@ func (pgc *Collection) GetExplicitCast(ctx *sql.Context, sourceType *pgtypes.Dol
 // GetAssignmentCast returns the assignment type cast function that will cast the source type to the target type.
 // Returns a Cast with an invalid ID if such a cast is not valid.
 func (pgc *Collection) GetAssignmentCast(ctx *sql.Context, sourceType *pgtypes.DoltgresType, targetType *pgtypes.DoltgresType) (Cast, error) {
-	castID := id.NewCast(sourceType.ID, targetType.ID)
-	c, err := pgc.getCast(ctx, castID, sourceType, targetType, CastType_Assignment)
+	castID := id.NewCast(sourceType.ID, targetType.ID)                              // TODO: expensive
+	c, err := pgc.getCast(ctx, castID, sourceType, targetType, CastType_Assignment) // TODO: expensive
 	if err != nil {
 		return Cast{}, err
 	}
@@ -146,7 +146,7 @@ func (pgc *Collection) GetAssignmentCast(ctx *sql.Context, sourceType *pgtypes.D
 		return c, nil
 	}
 	// We check for the identity and sizing casts after checking the maps, as the identity may be overridden by a user.
-	if cast := pgc.getSizingOrIdentityCast(sourceType, targetType, CastType_Assignment); cast.ID.IsValid() {
+	if cast := pgc.getSizingOrIdentityCast(castID, sourceType, targetType, CastType_Assignment); cast.ID.IsValid() {
 		return cast, nil
 	}
 	// We then check for a record to composite cast
@@ -193,7 +193,7 @@ func (pgc *Collection) GetImplicitCast(ctx *sql.Context, sourceType *pgtypes.Dol
 		return Cast{}, nil
 	}
 	// We check for the identity and sizing casts after checking the maps, as the identity may be overridden by a user.
-	if cast := pgc.getSizingOrIdentityCast(sourceType, targetType, CastType_Implicit); cast.ID.IsValid() {
+	if cast := pgc.getSizingOrIdentityCast(castID, sourceType, targetType, CastType_Implicit); cast.ID.IsValid() {
 		return cast, nil
 	}
 	// We then check for a record to composite cast
@@ -301,38 +301,29 @@ func (pgc *Collection) getCast(ctx context.Context, castID id.Cast, sourceType *
 // only differ in their atttypmod values. Returns a Cast with an invalid ID if no cast is matched. This mirrors the
 // behavior as described in:
 // https://www.postgresql.org/docs/15/typeconv-query.html
-func (pgc *Collection) getSizingOrIdentityCast(sourceType *pgtypes.DoltgresType, targetType *pgtypes.DoltgresType, castType CastType) Cast {
+func (pgc *Collection) getSizingOrIdentityCast(castID id.Cast, sourceType *pgtypes.DoltgresType, targetType *pgtypes.DoltgresType, castType CastType) Cast {
 	// If we receive different types, then we can return immediately
 	if sourceType.ID != targetType.ID {
 		return Cast{}
 	}
+	// TODO: We don't have any sizing cast functions implemented, so for now we'll approximate using output to input.
+	//  We can use the query below to find all implemented sizing cast functions. It's also detailed in the link above.
+	//  Lastly, not all sizing functions accept a boolean, but for those that do, we need to see whether true is
+	//  used for explicit casts, or whether true is used for implicit casts.
+	//      SELECT
+	//        format_type(c.castsource, NULL) AS source,
+	//        format_type(c.casttarget, NULL) AS target,
+	//        p.oid::regprocedure AS func
+	//      FROM pg_cast c JOIN pg_proc p ON p.oid = c.castfunc WHERE c.castsource = c.casttarget ORDER BY 1,2;
 	// If we have different atttypmod values, then we need to do a sizing cast only if one exists
-	if sourceType.GetAttTypMod() != targetType.GetAttTypMod() {
-		// TODO: We don't have any sizing cast functions implemented, so for now we'll approximate using output to input.
-		//  We can use the query below to find all implemented sizing cast functions. It's also detailed in the link above.
-		//  Lastly, not all sizing functions accept a boolean, but for those that do, we need to see whether true is
-		//  used for explicit casts, or whether true is used for implicit casts.
-		//      SELECT
-		//        format_type(c.castsource, NULL) AS source,
-		//        format_type(c.casttarget, NULL) AS target,
-		//        p.oid::regprocedure AS func
-		//      FROM pg_cast c JOIN pg_proc p ON p.oid = c.castfunc WHERE c.castsource = c.casttarget ORDER BY 1,2;
-		return Cast{
-			ID:       id.NewCast(sourceType.ID, targetType.ID),
-			CastType: castType,
-			Function: id.NullFunction,
-			BuiltIn:  nil,
-			UseInOut: true,
-			request:  castType,
-		}
-	}
-	// If there is no sizing cast, then we simply use the identity cast
+	// Otherwise, then we simply use the identity cast
+	useInOut := sourceType.GetAttTypMod() != targetType.GetAttTypMod()
 	return Cast{
-		ID:       id.NewCast(sourceType.ID, targetType.ID),
+		ID:       castID,
 		CastType: castType,
 		Function: id.NullFunction,
 		BuiltIn:  nil,
-		UseInOut: false,
+		UseInOut: useInOut,
 		request:  castType,
 	}
 }

core/id/id_wrappers.go

@@ -90,7 +90,18 @@ func NewCast(sourceType Type, targetType Type) Cast {
 	if len(sourceType) == 0 && len(targetType) == 0 {
 		return NullCast
 	}
-	return Cast(NewId(Section_Cast, string(sourceType), string(targetType)))
+
+	return Cast(
+		string(
+			[]byte{
+				uint8(Section_Cast),
+				2,
+				uint8(len(sourceType)),
+				uint8(len(targetType)),
+			}) +
+			string(sourceType) +
+			string(targetType),
+	)
 }
 
 // NewCheck returns a new Check. This wrapper must not be returned to the client.