9 Essential PHP Caching Techniques to Boost Web Performance

Today, the 21CTO editor shares nine major PHP caching techniques summarized by experts.

1. Full-page static cache

Generate the entire page as a static HTML file so that users receive the static page without invoking PHP. Common in CMS platforms like DedeCMS. Implemented via output buffering:

ob_start();
// code to run
$content = ob_get_contents();
// write $content to HTML file
ob_end_clean();

2. Partial page cache

Cache only the infrequently changing parts of a page while leaving dynamic blocks uncached. Can be done with output buffering or ESI fragment caching.

3. Data cache

Cache query results or other data in a PHP file identified by a unique key (e.g., product ID). Subsequent requests read the cached array instead of hitting the database. Used in Ecmall.

4. Query cache

Cache results based on the SQL statement. Store the result set in a file whose name is derived from the query, and reuse it for identical queries.

5. Time‑based cache

Set an expiration time for cached files; within that period the cache is used, after which fresh data is fetched and the cache regenerated.

6. Content‑change cache

Invalidate the cache immediately when the underlying database content changes, ensuring users always see up‑to‑date information.

7. In‑memory cache (Memcached)

Memcached provides a high‑performance distributed memory cache, typically storing key‑value pairs to reduce database load.

<?php
$memcachehost = '192.168.6.191';
$memcacheport = 11211;
$memcachelife = 60;
$memcache = new Memcache;
$memcache->connect($memcachehost,$memcacheport) or die ("Could not connect");
$memcache->set('key','cached content');
$get = $memcache->get($key); // retrieve
?>

8. Apache cache module

Enable mod_cache, mod_disk_cache, and mod_mem_cache when compiling Apache to allow server‑side caching.

9. Opcode cache

PHP parses code into tokens, compiles to opcodes, and executes them. Opcode caches (e.g., XCache, Turck MM Cache, PHP Accelerator) store the compiled opcodes so subsequent requests skip parsing and compilation.