You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: replication.rs
    path of file: ./repos/materialize/src/mysql-util/src
    
    the code of the file until where you have to start completion: // Copyright Materialize, Inc. and contributors. All rights reserved.
//
// Use of this software is governed by the Business Source License
// included in the LICENSE file.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0.

use mysql_async::prelude::Queryable;
use mysql_async::Conn;

use crate::MySqlError;

/// Query a MySQL System Variable
pub async fn query_sys_var(conn: &mut Conn, name: &str) -> Result<String, MySqlError> {
    let value: String = conn
        .query_first(format!("SELECT @@{}", name))
   
    
pub async fn ensure_replication_commit_order(conn: &mut Conn) -> Result<(), MySqlError> {
    // Determine if this is a replica by checking if there are any rows in the replica connection table
    let res: u8 = conn
        .query_first("SELECT COUNT(*) FROM performance_schema.replication_connection_configuration")
        .await?
        .unwrap();
    if res > 0 {
        // This system variable was renamed between MySQL 5.7 and 8.0
        match verify_sys_setting(conn, "replica_preserve_commit_order", "1").await {
            Ok(_) => Ok(()),
            Err(_) => verify_sys_setting(conn, "slave_preserve_commit_order", "1").await,
        }
    } else {
        Ok(())
    }
}