Do I need to worry about page caching?
 

Hi All, it seems I am a worrier.

On a large/busy site, would I need to worry about caching my pages? If say the pages were running around 25 queries in total? (Similar to talkphp\'s homepage but with more images.)

While I could prob easily cache the homepage and other top level pages to every ten mins or so, there would be hundreds of other pages that I wouldn't be able to cache so easily.

The server has memache installed (how effective is that anyway?).

Am I worrying over nothing? Or for a busy site should is caching essential?

Cheers,

That's quite a hard question to answer as it depends on your requests/second and whether your server can handle it :-)

As a general guide, I personally would probably implement a caching system if the site where getting more than about 10 requests per second or less if the site was paticularly server-intensive.

As for memcache, I've never used it so I can't really comment. I have used APC though which I liked a lot - worked well.

Alan

There are a number of levels of cache that you might want to think about implementing, each with their own particular advantages. I won't go through all of the different tiers but just highlight some. You could cache an entire rendered page and essentially serve it as static content, which would obviously be hugely beneficial but only if that's a usable situation -- eg. this is not possible if user-data ("Hello Salathe") is on the page.

You could cache particular portions of rendered HTML, maybe for sections that might be especially resource/time intensive but is pretty static (like lots of SQL queries for a sidebar, perhaps).

You could also cache database results meaning that for those cached queries/result-sets the time/memory needed to talk to the database and get back the results can be negated.

Another thing to ask, is caching really all that important a thing to implement right now for your application? Twenty-five well written queries isn't really such a terrible thing to worry about. But if you were worried then perhaps instead of, or along side, caching you could think about optimising and/or reducing the number of database queries.

I think the homepage and other top level pages will be possible to get cached but there will be lots of off-shoot pages that won't.

The other option is to go with Drupal - which has a caching system built in.. but then I've heard that for logged in users it's pretyt much switched off anyway. Plus I dunno, most 'large' Drupal sites I know always seem fairly slow to load up :-/