Preferred method to store PHP arrays (json_encode vs serialize)

Question

I need to store a multi-dimensional associative array of data in a flat file for caching purposes. I might occasionally come across the need to convert it to JSON for use in

Answer 1

Check out the results here (sorry for the hack putting the PHP code in the JS code box):

http://jsfiddle.net/newms87/h3b0a0ha/embedded/result/

RESULTS: serialize() and unserialize() are both significantly faster in PHP 5.4 on arrays of varying size.

I made a test script on real world data for comparing json_encode vs serialize and json_decode vs unserialize. The test was run on the caching system of an in production e-commerce site. It simply takes the data already in the cache, and tests the times to encode / decode (or serialize / unserialize) all the data and I put it in an easy to see table.

I ran this on PHP 5.4 shared hosting server.

The results were very conclusive that for these large to small data sets serialize and unserialize were the clear winners. In particular for my use case, the json_decode and unserialize are the most important for the caching system. Unserialize was almost an ubiquitous winner here. It was typically 2 to 4 times (sometimes 6 or 7 times) as fast as json_decode.

It is interesting to note the difference in results from @peter-bailey.

Here is the PHP code used to generate the results:

 basename($file),
        'json_encode() Time (s)' => $json_encode_time,
        'json_decode() Time (s)' => $json_decode_time,
        'serialize() Time (s)'   => $serialize_time,
        'unserialize() Time (s)' => $unserialize_time,
        'Elements'               => $count,
        'Memory (KB)'            => $memory,
        'Max Depth'              => $depth,
        'json_encode() Win'      => ($json_encode_time > 0 && $json_encode_time < $serialize_time) ? number_format(($serialize_time / $json_encode_time - 1) * 100, 2) : '',
        'serialize() Win'        => ($serialize_time > 0 && $serialize_time < $json_encode_time) ? number_format(($json_encode_time / $serialize_time - 1) * 100, 2) : '',
        'json_decode() Win'      => ($json_decode_time > 0 && $json_decode_time < $serialize_time) ? number_format(($serialize_time / $json_decode_time - 1) * 100, 2) : '',
        'unserialize() Win'      => ($unserialize_time > 0 && $unserialize_time < $json_decode_time) ? number_format(($json_decode_time / $unserialize_time - 1) * 100, 2) : '',
    );
}

$files = glob(dirname(__FILE__) . '/system/cache/*');

$data = array();

foreach ($files as $file) {
    if (is_file($file)) {
        $result = run_test($file);

        if ($result) {
            $data[] = $result;
        }
    }
}

uasort($data, function ($a, $b) {
    return $a['Memory (KB)'] < $b['Memory (KB)'];
});

$fields = array_keys($data[0]);
?>

 $value) { ?>