Cache or store in session? - php

Question

I have a page that has quite a lot of data loading from my db. I'd like to speed-up loading time. I already cache query, but still the loading time is longer than I'd like it to be.
Is it possible to render a table with data and store it in a session to load on every new page refresh? I was even thinking of putting it in an external text file using ob_start();
What's the best way to handle it?

Answer 1

Storing it in sessions is probably not the best idea, when you add data to a session (by default) the data is written to a file on the OS, usually in /tmp/ which means you're going to be hitting the disk quite a lot and storing just as much data.
If the data is not user specific then you could store it on disk, or in memory - (see: php.net/apc)
If the data is user specific, I recommend storing it in a distributed cache, such as Memcached (memcached.org) PHP has a library you can enable (php.net/memcached)
(by user specific I mean data like a users transactions, items, shopping cart, etc)
The logic is basically the same for any method you choose:
Memcached, user specific data example:
<?php
$memcached = new Memcached();
$data = $memcached->get('shopping-cart_' . $user_id);
if (!$data) {
$sql = $db->query("..");
$data = array();
while($row = $query->fetch_assoc()) {
$data[] = $row;
}
$memcached->set('shopping-cart_' . $user_id, $data);
}
?>
<table>
<?php
foreach ($data as $item) {
echo '<tr><td>' . $item['name'] .' </td></tr>';
}
?>
</table>
Global data (not user specific)
<?php
$cache_file = '/cached/pricing-structure.something';
if (file_exists($cache_file)) {
echo $cache_file;
} else {
// heavy query here
$h = fopen('/cached/pricing-structure.something', 'w+');
fwrite($h, $data_from_query);
fclose($h);
}

Answer 2

If you are doing caching on a single web server (as opposed to multiple distributed servers), PHP APC is a very easy-to-use solution. It is an in-memory cache, similar to memcache, but runs locally. I would avoid storing any significant amount of data in session.
APC is a PECL extension and can be installed with the command
pecl install apc
You may need to enable it in your php.ini.