I'm learning rust, and recently I'm trying to use the Sqlx library to connect to the database. Whether I use a pool or not, the connection speed is always at least 2s; however, when I use the Java Connector (mariadb-java-client package provided by mariadb.com) to connect to mariadb It takes less than 1 second and I don't quite understand why this is happening. I have used MysqlConnector of C# before, and it takes at least 2s to connect to mariadb. In the end, I also tried C Connector, C++ Connector and ODBC Connector, which are also slower than Java Connector.

kotlin sample code(using mariadb-java-client package):

fun main() {
    var timeStart = LocalTime.now().toNanoOfDay()
    Class.forName(dbClsName)
    var timeUsed = LocalTime.now().toNanoOfDay() - timeStart
    println("load class took time = $timeUsed ns")
    val p = Properties()
    p["user"] = userName
    p["password"] = password

    timeStart = LocalTime.now().toNanoOfDay()
    val conn = DriverManager.getConnection(connStr, p)
    timeUsed = LocalTime.now().toNanoOfDay() - timeStart
    val secs = timeUsed.toDouble() / 1e9
    println("connect successed! took time = $timeUsed ns, almost $secs s")

    timeStart = LocalTime.now().toNanoOfDay()
    val stmt = conn.createStatement()
    val rst = stmt.executeQuery("SHOW DATABASES;")
    timeUsed = LocalTime.now().toNanoOfDay() - timeStart
    println("query took time = $timeUsed ns")
    var i = 0
    while (rst.next()){
        i++
        println("result${i}:\n\t${rst.getString(1)}")
    }
    conn.close()
}

kotlin code result:

load class took time = 15631300 ns
connect successed! took time = 101765000 ns, almost 0.101765 s
query took time = 0 ns
...

Rust sample code(using sqlx):

#[tokio::main]
async fn main() -> Result<(), sqlx::Error> {
    let mut time_start = chrono::Local::now();
    let mut db_conn = MySqlConnection::connect(CONN_STR).await?;
    let duration_conn = chrono::Local::now() - time_start;
    println!(
        "connect db took time = {}ns, almost {}s",
        duration_conn.num_nanoseconds().unwrap_or_default(),
        duration_conn.num_seconds()
    );

    time_start = chrono::Local::now();
    let results = sqlx::query("SHOW DATABASES")
        .map(|row: MySqlRow| row.get::<String, usize>(0))
        .fetch_all(&mut db_conn)
        .await?;
    let query_duration = chrono::Local::now() - time_start;
    println!(
        "query db took time = {}ns, almost {}s",
        query_duration.num_nanoseconds().unwrap_or_default(),
        query_duration.num_seconds()
    );

    for row_str in results {
        println!("{}", row_str)
    }
    Ok(())
}

Rust sample result:

connect db took time = 2045829800ns, almost 2s
query db took time = 1324300ns, almost 0s
...

C# sample code(using MysqlConnector):

public static void Main() {
    var time_start = DateTime.UtcNow;
    using var conn = new MySqlConnection(connStr);
    var time_takes = DateTime.UtcNow - time_start;
    Console.WriteLine($"consturct connection finished; took time = {time_takes.Ticks}ticks, 
        almost {(long)time_takes.TotalSeconds}s");
    time_start = DateTime.UtcNow;
    conn.Open();
    time_takes = DateTime.UtcNow - time_start;
    Console.WriteLine($"open mysql connection finished; take time = {time_takes.Ticks}ticks, 
        almost {(long)time_takes.TotalSeconds}s");

    using var query_command = new MySqlCommand("SHOW DATABASES;", conn);
    using var reader_dbs = query_command.ExecuteReader();
    while (reader_dbs.Read())
    {
        Console.WriteLine(reader_dbs.GetString(0));
    }
}

C# sample result:

consturct connection finished; took time = 1597ticks, almost 0s
open mysql connection finished; take time = 22826302ticks, almost 2s
...

In addition, please ignore that I didn't measure the elapsed time with a benchmarking library, because the difference of the connection time between the Java connector and other connectors is visible to the naked eye.