Wizard's Blog

I’ve been using the WP Super Cache plug-in on my blog for a while.  I’m quite happy with it, although I doubt my website gets enough traffic to really need it.

WP Super Cache does have one drawback – it only caches a page after it has been accessed the first time, so if a lot of pages are accessed just once (for example when a search engine crawls your website) you get no benefit from the caching.  This is understandable considering WP Super Cache was designed to help when a single page is accessed a lot of times (e.g. the digg effect).

I recently found out about DB Cache (I don’t remember where from), which is a similar plug-in in that it’s intended to speed up your website and reduce the load on the server.  However it works differently from WP Super Cache in that instead of caching pages it caches database queries.

This means that DB Cache provides less of an improvement when a single page gets a lot of hits, because PHP still runs for every hit – only the database queries are sped up.  In this case WP Super Cache would be faster because PHP only needs to run on the first hit, and from then on it’s serving static HTML.

The case where DB Cache provides more of an improvement over WP Super Cache is when lots of different pages get hits around the same time (e.g. when a search engine crawls your website).  In this case WP Super Cache never gets to serve static pages, so it doesn’t provide any improvement.  However because hits on different pages will use a lot of the same database queries, DB Cache will be able to speed this up.

I’m currently using both DB Cache and WP Super Cache at the same time, and they seem to co-exist without any problems.  This way I get the best of both worlds – either a page is already in WP Super Cache and a static page gets served, or the page is being accessed for the first time and so the database queries get cached by DB Cache.

Unlike most of the other plug-ins I use, the author of the DB Cache plug-in isn’t a native English speaker (he’s Ukrainian) so help and support seem to be more of a challenge than usual.

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