fix(sink): Relax some alter table column conditions (#23142)

Co-authored-by: Chiro11 <[email protected]>

Author: Chiro11

e2e_test/sink/sink_into_table/alter_column.slt

@@ -355,3 +355,43 @@ drop table m_drop_1;
 
 statement ok
 drop table t_drop_1;
+
+statement ok
+create table t1 (v1 int);
+
+statement ok
+create table t2 (v1 int primary key, v2 int as v1 + 10, v3 timestamptz as proctime());
+
+statement ok
+create sink s1 into t2 from t1;
+
+statement ok
+insert into t1 values (1), (2);
+
+query II rowsort
+select v1, v2 from t2;
+----
+1 11
+2 12
+
+statement ok
+alter table t2 add column v4 int default 100;
+
+statement ok
+insert into t1 values (3);
+
+query III rowsort
+select v1, v2, v4 from t2;
+----
+1 11 100
+2 12 100
+3 13 100
+
+statement ok
+drop sink s1;
+
+statement ok
+drop table t1;
+
+statement ok
+drop table t2;

src/frontend/src/handler/alter_table_column.rs

@@ -126,13 +126,6 @@ pub async fn handle_alter_table_column(
     let (original_catalog, has_incoming_sinks) =
         fetch_table_catalog_for_alter(session.as_ref(), &table_name)?;
 
-    if has_incoming_sinks && original_catalog.has_generated_column() {
-        return Err(RwError::from(ErrorCode::BindError(
-            "Alter a table with incoming sink and generated column has not been implemented."
-                .to_owned(),
-        )));
-    }
-
     if original_catalog.webhook_info.is_some() {
         return Err(RwError::from(ErrorCode::BindError(
             "Adding/dropping a column of a table with webhook has not been implemented.".to_owned(),