feat(frontend): introduce system catalog table pg_enum (risingwavelab…

…s#7706)

Introduce system catalog table `pg_enum`.

Approved-By: neverchanje

e2e_test/batch/catalog/pg_enum.slt.part

@@ -0,0 +1,3 @@
+query IIIT
+SELECT * FROM pg_catalog.pg_enum;
+----

src/frontend/src/catalog/system_catalog/mod.rs

@@ -202,6 +202,7 @@ prepare_sys_catalog! {
     { PG_CATALOG, PG_SHDESCRIPTION, vec![0], read_shdescription_info },
     { PG_CATALOG, PG_TABLESPACE, vec![0], read_tablespace_info },
     { PG_CATALOG, PG_STAT_ACTIVITY, vec![0], read_stat_activity },
+    { PG_CATALOG, PG_ENUM, vec![0], read_enum_info },
     { INFORMATION_SCHEMA, COLUMNS, vec![], read_columns_info },
     { INFORMATION_SCHEMA, TABLES, vec![], read_tables_info },
     { RW_CATALOG, RW_META_SNAPSHOT, vec![], read_meta_snapshot await },

src/frontend/src/catalog/system_catalog/pg_catalog/mod.rs

@@ -20,6 +20,7 @@ pub mod pg_class;
 pub mod pg_collation;
 pub mod pg_database;
 pub mod pg_description;
+pub mod pg_enum;
 pub mod pg_index;
 pub mod pg_keywords;
 pub mod pg_matviews;
@@ -46,6 +47,7 @@ pub use pg_class::*;
 pub use pg_collation::*;
 pub use pg_database::*;
 pub use pg_description::*;
+pub use pg_enum::*;
 pub use pg_index::*;
 pub use pg_keywords::*;
 pub use pg_matviews::*;
@@ -250,6 +252,10 @@ impl SysCatalogReaderImpl {
         Ok(vec![])
     }
 
+    pub(crate) fn read_enum_info(&self) -> Result<Vec<OwnedRow>> {
+        Ok(vec![])
+    }
+
     pub(super) fn read_roles_info(&self) -> Result<Vec<OwnedRow>> {
         let reader = self.user_info_reader.read_guard();
         let users = reader.get_all_users();

src/frontend/src/catalog/system_catalog/pg_catalog/pg_enum.rs

@@ -0,0 +1,28 @@
+// Copyright 2023 RisingWave Labs
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use risingwave_common::types::DataType;
+
+use crate::catalog::system_catalog::SystemCatalogColumnsDef;
+
+/// The `pg_enum` catalog contains entries showing the values and labels for each enum type.
+/// The internal representation of a given enum value is actually the OID of its associated row in
+/// `pg_enum`. Reference: [`https://www.postgresql.org/docs/current/catalog-pg-enum.html`]
+pub const PG_ENUM_TABLE_NAME: &str = "pg_enum";
+pub const PG_ENUM_COLUMNS: &[SystemCatalogColumnsDef<'_>] = &[
+    (DataType::Int32, "oid"),
+    (DataType::Int32, "enumtypid"),
+    (DataType::Float32, "enumsortorder"),
+    (DataType::Varchar, "enumlabel"),
+];