Serialize or json in PHP?

Solution 1:

Main advantage of serialize : it's specific to PHP, which means it can represent PHP types, including instances of your own classes -- and you'll get your objects back, still instances of your classes, when unserializing your data.

Main advantage of json_encode : JSON is not specific to PHP : there are libraries to read/write it in several languages -- which means it's better if you want something that can be manipulated with another language than PHP.

A JSON string is also easier to read/write/modify by hand than a serialized one.

On the other hand, as JSON is not specific to PHP, it's not aware of the stuff that's specific to PHP -- like data-types.

As a couple of sidenotes :

• Even if there is a small difference in speed between those two, it shouldn't matter much : you will probably not serialize/unserialize a lot of data
• Are you sure this is the best way to store data in a database ?
  • You won't be able to do much queries on serialized strins, in a DB : you will not be able to use your data in where clauses, nor update it without the intervention of PHP...

Solution 2:

I did some analysis on Json Encoding vs Serialization in PHP. And I found that Json is best for plain and simple data like array.

See the results of my experiments at https://www.shozab.com/php-serialization-vs-json-encoding-for-an-array/

Solution 3:

Another advantage of json_encode over serialize is the size. I noticed that as I was trying to figure out why our memcache used memory was getting so big, and was trying to find ways to reduce is:

<?php

$myarray = array();
$myarray["a"]="b";
$serialize=serialize($myarray);
$json=json_encode($myarray);
$serialize_size=strlen($serialize);
$json_size=strlen($json);
var_dump($serialize);
var_dump($json);
echo "Size of serialized array: $serialize_size\n";
echo "Size of json encoded array: $json_size\n";
echo "Serialize is " . round(($serialize_size-$json_size)/$serialize_size*100) . "% bigger\n";

Which gives you:

string(22) "a:1:{s:1:"a";s:1:"b";}"
string(9) "{"a":"b"}"
Size of serialized array: 22
Size of json encoded array: 9
Serialize is 59% bigger

Obviously I've taken the most extreme example, as the shorter the array, the more important the overhead with serialize (relative to the initial object size, due to formatting which imposes a minimum number of characters no matter how small the content). Still from a production website I see serialized array that are 20% bigger than their json equivalent.