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 my web app but the vast majority of the time I will be using the array directly in PHP.
Would it be more efficient to store the array as JSON or as a PHP serialized array in this text file? I've looked around and it seems that in the newest versions of PHP (5.3), json_decode
is actually faster than unserialize
.
I'm currently leaning towards storing the array as JSON as I feel its easier to read by a human if necessary, it can be used in both PHP and JavaScript with very little effort, and from what I've read, it might even be faster to decode (not sure about encoding, though).
Does anyone know of any pitfalls? Anyone have good benchmarks to show the performance benefits of either method?
The json_encode() function is used to encode a value to JSON format.
JSON data structures are very similar to PHP arrays. PHP has built-in functions to encode and decode JSON data. These functions are json_encode() and json_decode() , respectively. Both functions only works with UTF-8 encoded string data.
The json_decode() function can return a value encoded in JSON in appropriate PHP type. The values true, false, and null is returned as TRUE, FALSE, and NULL respectively. The NULL is returned if JSON can't be decoded or if the encoded data is deeper than the recursion limit.
The PHP json_encode function translates the data passed to it to a JSON string which can then be output to a JavaScript variable. We demonstrate on this page with single level arrays. Other pages demonstrate using json_encode with multi-dimensional arrays and scalar values.
Depends on your priorities.
If performance is your absolute driving characteristic, then by all means use the fastest one. Just make sure you have a full understanding of the differences before you make a choice
serialize()
you need to add extra parameter to keep UTF-8 characters untouched: json_encode($array, JSON_UNESCAPED_UNICODE)
(otherwise it converts UTF-8 characters to Unicode escape sequences).__sleep()
and __wakeup()
with JSONPHP>=5.4
you can implement JsonSerializable to change this behavior).And there's probably a few other differences I can't think of at the moment.
A simple speed test to compare the two
<?php ini_set('display_errors', 1); error_reporting(E_ALL); // Make a big, honkin test array // You may need to adjust this depth to avoid memory limit errors $testArray = fillArray(0, 5); // Time json encoding $start = microtime(true); json_encode($testArray); $jsonTime = microtime(true) - $start; echo "JSON encoded in $jsonTime seconds\n"; // Time serialization $start = microtime(true); serialize($testArray); $serializeTime = microtime(true) - $start; echo "PHP serialized in $serializeTime seconds\n"; // Compare them if ($jsonTime < $serializeTime) { printf("json_encode() was roughly %01.2f%% faster than serialize()\n", ($serializeTime / $jsonTime - 1) * 100); } else if ($serializeTime < $jsonTime ) { printf("serialize() was roughly %01.2f%% faster than json_encode()\n", ($jsonTime / $serializeTime - 1) * 100); } else { echo "Impossible!\n"; } function fillArray( $depth, $max ) { static $seed; if (is_null($seed)) { $seed = array('a', 2, 'c', 4, 'e', 6, 'g', 8, 'i', 10); } if ($depth < $max) { $node = array(); foreach ($seed as $key) { $node[$key] = fillArray($depth + 1, $max); } return $node; } return 'empty'; }
JSON is simpler and faster than PHP's serialization format and should be used unless:
json_decode()
: "This function will return false if the JSON encoded data is deeper than 127 elements."If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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