// Copyright 2022 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::Fields;
use risingwave_frontend_macro::system_catalog;

/// The catalog `pg_description` stores description.
/// Ref: `https://www.postgresql.org/docs/current/catalog-pg-description.html`
#[system_catalog(view, "pg_catalog.pg_description",
    // objsubid = 0     => _row_id (hidden column)
    // objsubid is NULL => table self
    "SELECT objoid,
        classoid,
        CASE
            WHEN objsubid = 0 THEN -1
            WHEN objsubid IS NULL THEN 0
            ELSE objsubid
        END AS objsubid,
        description
    FROM rw_catalog.rw_description
    WHERE description IS NOT NULL;"
)]
#[derive(Fields)]
struct PgDescription {
    objoid: i32,
    classoid: i32,
    objsubid: i32,
    description: String,
}
