Why is MySQL caching data on our dynamic PHP site? We are having an annoyance with our PHP/MySQL site in that it seems to cache data from the database and our PHP pages are showing out of date records. In fact, there are pages that link to URLs that have been completely removed from the database, yet they do not show updated records or even missing data.

If we have the patience of waiting several (undefined) hours, the data will eventually show up. I've added the regular no-cache headers via PHP on all of the pages, but it doesn't seem to affect the MySQL output. 

The PHP portion of the site is instantly updateable though, and shows HTML etc changes immediately. Is there a way to force MySQL to only draw fresh data from its queries? I thought this was the way it worked anyways!

Thanks,
Chris

P.S. Here are the php codes I'm using to try to force a no cache situation:

header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); // Date in the past
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); // Always modified
header("Cache-Control: private, no-store, no-cache, must-revalidate"); // HTTP/1.1 
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache"); // HTTP/1.0
Nothing that MySQL does will lead to stale data -- not the Query cache, not SQL_CACHE, not the key_buffer, not the buffer_pool.  The problem must be outside MySQL.