The description to David McNicol’s URL Cache Plugin raises more questions than it answers:

Given a URL, the url_cache() function will attempt to download the file it represents and return a URL pointing to this locally cached version.

Where did he plan to use it? Does he envision the cache as an archive, or for performance? Why hasn’t it been updated since 2005?

It caught my interest because I’ve long been interested in a solution to link rot in my blog. A real “perma-permalink” would be very useful.

Jacob Santos‘ FuncDoc notes:

The WordPress Object Cache changed in WordPress 2.5 and removed a lot of file support from the code. This means that the Object Cache in WordPress 2.5 is completely dependent on memory and will not be saved to disk for retrieval later. The constant WP_CACHE also changed its meaning.

I’ve just started using the object cache and I’m happy with how it works now, so these changes are somewhat concerning. On the other hand, I’m confident that I’ll see even more performance gains once I get my head around the new cache and figure out how to implement it.

Extra: Peter Westwood’s Cache Inspect looks useful.

I wrote bsuite_speedcache to reduce the number of database queries I was executing per page load. By implementing it on some of the content in my sidebar, I dropped 35 queries for each cache hit. That might not seem like much, but it should average about 525 queries per minute that that my host server won’t need to process.

Now that I’m looking seriously at optimizing my queries, I’ve also cut the monthly archives links from the sidebar. The SELECT DISTINCT query it relies on hits MySQL hard. It wouldn’t be so bad if the get_archives function could be set to return the results (and my attempts at output buffering seemed to conflict with something else within WP), but it can’t and without being able to feed the results into the cache it has to be re-queried with every page load.

Between removing the archives links and bsuite_speedcache, I’ve gone from 136 to 99 queries for the front page and my story pages went from 65 to 28.

Where is it?

I’m going to ask my pal Zach (who knows a lot more about MySQL optimization than I do) to take a look at it with an eye toward making sure I’m not missing any easy optimization opportunities (and that I’m not causing trouble in one area I’ve got a question about).

With that done, and after I add some code to create the DB table and such, I’ll try to release it sometime this week.

tags: bsuite_speedcache, bsuite, cache, cache hit, codex, database, database caching, database optimization, database performance, database queries, mysql, mysql caching, mysql optimization, mysql performance, mysql queries, wordpress, wordpress optimization, wordpress performance, wordpress performance optimization, wordpress plugin