pdo.php

<?php

class PDOConnection extends PDO {

    public function prepare($prepareString, $driverOptions = []): PDOStatement|false
    {
        return parent::prepare($prepareString, $driverOptions);
    }
}

print(memory_get_usage() . "\n");

$dbh = new PDOConnection('sqlite:memory');
//$dbh->exec('CREATE TABLE user (active BOOL, admin BOOL, created_at DATE, updated_at DATE)');

print(memory_get_usage() . "\n");

for($i = 0; $i < 100; $i++) {

    // Obviously we normally would not generate a new identical prepared statement inside
    // of a loop, but this demonstrates the problem well, and an ORM using PDOConnection
    // (e.g. Laravel Eloquent) does actually generate a new prepared statement for each
    // query, expecting that the statement will be properly destroyed once all references
    // to it are destroyed.
    $stmt = $dbh->prepare(
        "INSERT INTO user (active, admin, created_at, updated_at) VALUES (?, ?, ?, ?)");

    if($i == 0) {
        print(memory_get_usage() . "\n");
    }

    $stmt->execute([1, 1, '2018-01-01', '2018-01-01']);

    if($i == 0) {
        print(memory_get_usage() . "\n");
    }

}

$stmt = null;

print(memory_get_usage() . "\n");

$dbh = null;
print(memory_get_usage() . "\n");