risingwave_frontend/expr/function_impl/
col_description.rs

1// Copyright 2025 RisingWave Labs
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use std::fmt::Write;
16
17use risingwave_expr::{ExprError, function};
18
19#[function("col_description(varchar, int4) -> varchar")]
20fn col_description(_name: &str, _col: i32, writer: &mut impl Write) -> Result<(), ExprError> {
21    // TODO: Currently we don't support `COMMENT` statement, so we just return empty string.
22    writer.write_str("").unwrap();
23
24    Ok(())
25}