Memcache vs APC for a single server site data caching

Question

I have a single server site thats pushing 200k unqiues per day, and the traffic doubles roughly every 40 days (for the last 5 months anyway).

I pretty much only plan to

Answer 1

Like you mentioned there are a few different aspects of caching. I probably would focus on the following aspects of caching in your php app:

• opcode caching which caches the compiled bytecode of php scripts. You can see a benchmark here (albeit an older article): http://itst.net/654-php-on-fire-three-opcode-caches-compared Note: I strongly recommend using opcode caching.

• Caching user data - APC and others do this. This would be your reference data or data that is fairly static and doesn't change often. You can clear the cache every day or trigger a clean cache when this reference data changes. This is also strongly recommended since typically reference data is used frequently and doesn't change often.

• Caching sql queries - I know that Zend makes this task easy with a simple setup. Since these queries don't change this is another obvious one (like you mentioned)

Additional (if possible):

• caching html pages - obviously caching a static page is faster than a generated one and typically this is hard to do since most pages in apps are so dynamic. Worth it if you can do it although if your queries are cached and your SQL is simple I wouldn't focus on this.

• caching sql results - personally I stay away from this. I'll let the database do its work and what it does best since the DBMS typically has caching. I may cache the results for the thread of execution (i.e., I just retrieved this so don't do it again) but I don't go much beyond that.

I've used APC and eAccelerator successfully (I personally like to work with APC and it supposed opcode caching and user data caching for my reference data and sql queries). Use XDebug to profile your code.