使用远程数据库时简单Eloquent查询太慢

Question

Question Edit

Server

32 GB RAM
innodb_buffer_pool_size=1400M

Database

Fresh empty table:

fields(id, name, type, optional)

SHOW TABLE STATUS LIKE "fields" result

Name:fields|Engine:InnoDB|Row_format:Dynamic|Rows:0|Av_row_length:0|Data_length:16384|Max_data_length:0|Data_free:0|Auto_increment:null|Create_time:2022-08-01 12:52:42|Update_time:NULL|Check_time:NULL|Collation:utf8_general_ci|Checksum:NULL|Create_options:|Comment:|Max_index_length:0|Temporary:N

Test code

Route::get('/', function () {
    $gtc = microtime(true);
    DB::connection()->getPdo();
    $total = round((microtime(true) - $gtc) * 1000);
    echo "Laravel Connection time: $total ms<br>";

    $gtc = microtime(true);
    DB::select('SELECT * FROM fields');
    $total = round((microtime(true) - $gtc) * 1000);
    echo "Laravel Get rows time: $total ms<br>";

    $gtc = microtime(true);
    DB::select('SELECT 1');
    $total = round((microtime(true) - $gtc) * 1000);
    echo "Laravel SELECT time: $total ms<br>";

    $gtc = microtime(true);
    $pdo = new MySQLModel(env('DB_HOST'), env('DB_DATABASE'), env('DB_USERNAME'), env('DB_PASSWORD'));
    $connection = $pdo->getConnection();
    $total = round((microtime(true) - $gtc) * 1000);
    echo "PDO Connection time: $total ms<br>";

    $gtc = microtime(true);
    $ps = $connection->prepare('SELECT* FROM fields');
    $ps->execute();
    $total = round((microtime(true) - $gtc) * 1000);
    echo "PDO Get rows time: $total ms<br>";

    $gtc = microtime(true);
    $ps = $connection->prepare('SELECT 1');
    $ps->execute();
    $total = round((microtime(true) - $gtc) * 1000);
    echo "PDO SELECT time: $total ms<br>";

    for($i = 0; $i<5; $i++) {
        print_r(DB::select('SELECT NOW(3)'));
        echo '<hr>';
    }
});

Results

Laravel Connection time: 549 ms
Laravel Get rows time: 136 ms
Laravel SELECT time: 137 ms
PDO Connection time: 282 ms
PDO Get rows time: 68 ms
PDO SELECT time: 68 ms
Array ( [0] => stdClass Object ( [NOW(3)] => 2022-08-01 13:24:10.784 ) ) 
Array ( [0] => stdClass Object ( [NOW(3)] => 2022-08-01 13:24:10.921 ) ) 
Array ( [0] => stdClass Object ( [NOW(3)] => 2022-08-01 13:24:11.057 ) ) 
Array ( [0] => stdClass Object ( [NOW(3)] => 2022-08-01 13:24:11.193 ) ) 
Array ( [0] => stdClass Object ( [NOW(3)] => 2022-08-01 13:24:11.333 ) ) 

This does not happen if the database is located in the same server but when connecting with the remote one.

It all points it is a connection issue related with Eloquent and I haven't found any information about configuring something to prevent such a huge increase in query execution (tends to doubles it in all test I have made).

Answer 1

Inconsistent timing:

Don't turn on the stopwatch. The first fetch is slower because of fetching data from disl; the rest run faster. due to caching.

Tuning:

What is the value of innodb_buffer_pool_size ? How much RAM does the server have?

Connecting:

The program should connect only once, and do it before starting any timing tests. Time the connection separately. (Yes, 400ms to connect is absurd.)

Data_length:

16K is the 'minimum' size of a non-empty table. That is 1 block. Even on the least powerful local machine, the SELECT * FROM t should take under 10ms.

Next steps:

If you can instrument Eloquent this way, we can focus on the connection , not be distracted by the SELECTs:

Print the time just and just after before making the connection.

If that is not practical, then change the query to simply SELECT 1 .

Another approach is to perform and display SELECT NOW(3) in a loop 5 times. This should demonstrate whether Eloquent is reconnecting!

Answer 2

It is Laravel default config fault , it will query the server multiple times to setup the * * database instead of creating a single SQL Query to send to MySQL.

Set charset to null in config/database.php

'charset' => null,

It will prevent Laravel sending a

"set names '{$config['charset']}'".$this->getCollation($config)

query to the server.

Next set strict to NULL in config/app.php in the mysql key

'strict' => null,

It will prevent Laravel from

$connection->prepare($this->strictMode($connection, $config))->execute();

or

$connection->prepare("set session sql_mode='NO_ENGINE_SUBSTITUTION'")->execute();

This will prevent server communication delay which results the connection request to the server be a lot faster.

Laravel Connection time: 268 ms

For the SELECT queries taking double time it is due

$statement = $this->prepared(
                $this->getPdoForSelect($useReadPdo)->prepare($query)
            );//+68 ms more!

which communicates with the server for PDO prepare.

$statement->execute();//+68 ms more!

Set PDO::ATTR_EMULATE_PREPARES => true in the options key within mysql array set to enable emulated prepares and increase performance.

The performance should be almost equal to PDO now.