PDO/Sqlite not persisting metrics

[apms75]

I tried to setup PDO/Sqlite (Windows 11, prometheus_client_php 2.13.0) with the 2 end-points:

$registry = new \Prometheus\CollectorRegistry(new \Prometheus\Storage\PDO(new \PDO('sqlite::memory:')));

$counter = $registry->registerCounter('test', 'some_counter', 'it increases', ['type']);
$counter->incBy(3, ['blue']);

$registry = new \Prometheus\CollectorRegistry(new \Prometheus\Storage\PDO(new \PDO('sqlite::memory:')));

$renderer = new \Prometheus\RenderTextFormat();
$result = $renderer->render($registry->getMetricFamilySamples());

header('Content-type: ' . \Prometheus\RenderTextFormat::MIME_TYPE);
print($result."\n");

The second end-point keeps returning

# HELP php_info Information about the PHP environment.
# TYPE php_info gauge
php_info{version="8.4.1"} 1

Note: I had to change the line building $registry as the original line from the example in https://github.com/PromPHP/prometheus_client_php/README.md: $registry = new CollectorRegistry(new \PDO('sqlite::memory:')); triggers an error

If I persist the database in a file with new \PDO('sqlite:C:/temp/prom.sqlite'), I get this error the second time I run any of the 2 scripts:

Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 1 index name already exists in...

It's working well after adding an IF NOT EXISTS in PDO.php line 644

$sqlIndex = "CREATE INDEX IF NOT EXISTS `name` ON `{$this->prefix}_summaries`(`name`);";);";

[LKaemmerling]

Hey @apms75,

the registry instance needs to be singleton. You can not have two parallel instances operating on the same database.