Speed comparison PHP 7.0 vs. 7.2 vs. 7.4 using MySQL PDO connection

Published on July 21st 2020

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While troubleshooting to find the reason for slow database connections from a PHP application (running in a Kubernetes container environment), the PHP version itself was tested as well. Would another PHP version improve performance? We're about to find out.

The test script

A simple PHP script (mysqltest.php) was created. It basically connects to a given MySQL/MariaDB server using the connection credentials at the begin and runs in a loop for 10'000 cycles. During each loop run, a basic SELECT NOW() query is executed on the database server.

<?php
$user = "user";
$password = "password";
$host = "mysqlserver";

try {
    $conn = new PDO("mysql:host=$host", $user, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $queries = 10000;
    $startTime = microtime(true);
    for ($i = 0; $i < $queries; $i++) {
        $result = $conn->query("SELECT NOW()")->fetchAll();
    }
    $elapsedTime = microtime(true) - $startTime;
    $elapsedTime = round($elapsedTime, 6);
    $averageTime = number_format($elapsedTime / $queries, 10);
    echo "Time for $queries queries: $elapsedTime \n";
    echo "Average time per query: $averageTime\n";
} catch(PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}

At the end, the script returns the total run time needed to execute the 10k queries and an average time per query (thanks to Stefan Stefanov who created the script).

Ubuntu Xenial with PHP 7.0

A new container with Ubuntu 16.04 (Xenial) was started (using the image ubuntu:xenial) and the following packages were installed:

root@xenial-6586845d5f-wr4hf:/# apt-get update && apt-get install php7.0-cli php7.0-mysql

Then the script was executed twice (with a pause of 2 min):

root@xenial-6586845d5f-wr4hf:~# php mysqltest.php && sleep 120 && php mysqltest.php
Time for 10000 queries: 17.596321
Average time per query: 0.0017596321
Time for 10000 queries: 18.602951
Average time per query: 0.0018602951

Ubuntu Bionic with PHP 7.2

A new container with Ubuntu 18.04 (Bionic) was started (using the image ubuntu:bionic) and the following packages were installed:

root@bionic-f74f657c4-xqbv6:/# apt-get update && apt-get install php7.2-cli php7.2-mysql

Then the script was executed twice (with a pause of 2 min):

root@wislog-f74f657c4-xqbv6:~# php mysqltest.php && sleep 120 && php mysqltest.php
Time for 10000 queries: 16.110461
Average time per query: 0.0016110461
Time for 10000 queries: 16.35995
Average time per query: 0.0016359950

Ubuntu Focal with PHP 7.4

A new container with Ubuntu 20.04 (Focal) was started (using the image ubuntu:focal) and the following packages were installed:

root@focal-c46b7b945-b8lvr:/# apt-get update && apt-get install php7.4-cli php7.4-mysql

Then the script was executed twice (with a pause of 2 min):

root@focal-c46b7b945-b8lvr:~# php mysqltest.php && sleep 120 && php mysqltest.php
Time for 10000 queries: 14.528925
Average time per query: 0.0014528925
Time for 10000 queries: 16.701757
Average time per query: 0.0016701757

Comparison

Having now tested the currently active Ubuntu LTS releases and their native PHP version, a side by side comparison reveals a major performance jump from PHP 7.0 to 7.2 (yes, 10% is pretty good!) and then another, minor, performance improvement from PHP 7.2 to 7.4.

Version	Try #1	Try #2	Avg Runtime	Improv. %
PHP 7.0	17.596321	18.602951	18.099636	0
PHP 7.2	16.110461	16.35995	16.2352055	10.30 vs. PHP 7.0
PHP 7.4	14.528925	16.701757	15.615341	13.73 vs. PHP 7.0