Avoid to many SQL query on page reload - php

Question

I have a website page that, on load, fires 10 different queries against a table with 150,000,000 rows.
Normally the page loads in under 2 seconds - but if I refresh too often, it creates a lot of queries, which slow page load time by up to 10 seconds.
How can I avoid firing all of those queries, since it would kill my database?
I have no caching yet. The site works in the following way. I have a table were all URIs are stored. If a user enters a URL I grap the URI out of the called URL and check in the table if the URI is stored. In case the URI is stored in the table I pull the corresponding data from the other tables in a relational database.
An example code from one of the PHP files that pulls the information from the other tables is this
<?php
set_time_limit(2);
define('MODX_CORE_PATH', '/path/to/modx/core/');
define('MODX_CONFIG_KEY','config');
require_once MODX_CORE_PATH . 'model/modx/modx.class.php';
// Criteria for foreign Database
$host = 'hostname';
$username = 'user';
$password = 'password';
$dbname = 'database';
$port = 3306;
$charset = 'utf8mb4';
$dsn = "mysql:host=$host;dbname=$dbname;port=$port;charset=$charset";
$xpdo = new xPDO($dsn, $username, $password);
// Catch the URI that is called
$pageURI = $_SERVER["REQUEST_URI"];
// Get the language token saved as TV "area" in parent and remove it
if (!isset($modx)) return '';
$top = isset($top) && intval($top) ? $top : 0;
$id= isset($id) && intval($id) ? intval($id) : $modx->resource->get('id');
$topLevel= isset($topLevel) && intval($topLevel) ? intval($topLevel) : 0;
if ($id && $id != $top) {
$pid = $id;
$pids = $modx->getParentIds($id);
if (!$topLevel || count($pids) >= $topLevel) {
while ($parentIds= $modx->getParentIds($id, 1)) {
$pid = array_pop($parentIds);
if ($pid == $top) {
break;
}
$id = $pid;
$parentIds = $modx->getParentIds($id);
if ($topLevel && count($parentIds) < $topLevel) {
break;
}
}
}
}
$parentid = $modx->getObject('modResource', $id);
$area = "/".$parentid->getTVValue('area');
$URL = str_replace($area, '', $pageURI);
$lang= $parentid->getTVValue('lang');
// Issue queries against the foreign database:
$output = '';
$sql = "SELECT epf_application_detail.description FROM epf_application_detail INNER JOIN app_uri ON epf_application_detail.application_id=app_uri.application_id WHERE app_uri.uri = '$URL' AND epf_application_detail.language_code = '$lang'";
foreach ($xpdo->query($sql) as $row) {
$output .= nl2br($row['description']);
}
return $output;

Answer 1

Without knowing what language you're using, here is some pseudo-code to get you started.
Instead of firing a large query every time your page loads, you could create a separate table called something like "cache". You could run your query and then store the data from the query in that cache table. Then when your page loads, you can query the cache table, which will be much smaller, and won't bog things down when you refresh the page a lot.
Pseudo-Code (which can be done on an interval using a cronjob or something, to keep your cache fresh.):
Run your ten large queries
For each query, add the results to cache like so:
query_id | query_data
----------------------------------------------------
1 | {whatever your query data looks like}
Then, when your page loads, have each query collect the data from cache
It is important to note, that with a cache table, you will need to refresh it often. (either as often as you get more data, or on a set interval, like every 5 minutes or something.)

Answer 2

You should do some serverside caching and optimizations.
If I was you I would install Memcached for your database.
I would also consider some static caching like Varnish, this will cache every page as static HTML, With varnish the 2nd (and 3th, 4th,...) request doesn't have to be handled by PHP and MySQL, which will make it load a lot faster when you load it for the 2nd time (within the cache lifetime ofcourse).
Last of all you can help the PHP side handle the data better by installing APC (or an other opcode cache).