Not a day goes by without us noticing this inconsistency in Joomla: it’s confusing, it’s weird, and it’s very dangerous. We know, you have no idea what we’re talking about at the moment. Let us explain…
Login to the backend of your Joomla website, and then go to Site -> Global Configuration, and then click on the System tab. On the right side, under Cache Settings, you will see Cache Time, which is the default time that Joomla will cache modules (and pages, if you’ve enabled the System – Cache plugin) for. Cache Time is set to 15 by default. Now, if you hover on the label Cache Time, you will see the following explanation:
The maximum length of time in minutes for a cache file to be stored before it is refreshed.
You’ll know why we highlighted in minutes in just under a minute (pun intended).
Now, go to Extensions -> Module Manager, and click on any module of type Menu (for example, your Main Menu module), and then click Advanced Options on the right. The last field under Advanced Options is Cache Time, and it is set, by default to, 900. Now, if you hover on Cache Time here, you will see the following popup message:
The time before the module is recached
Hmmm… The time in what? In minutes? In seconds? In days? Since we have a lot of experience in Joomla, we know that it’s in seconds, and that’s why it’s defaulted to 900 (which translates to 15 minutes), but, unfortunately, not everyone has the same Joomla experience that we have, and this might be very confusing and dangerous (if you’re heavily using caching on your website, and you are assuming that everything is in minutes).
We have no idea why was this inconsistency not addressed in Joomla 2.5. We also have no idea why the popup message for the module does not specify the unit of time, if it did, everything would be much clearer (it literally takes 1 minute to fix this in the language file).
This is more or less like a rant, but a positive rant, and we’ll make sure that the Joomla developers know about it, so that they can fix it. Meanwhile, always remember that only the Global Cache is in minutes, everything else is in seconds. Oh, and while we’re on the same subject, if you have a caching problem on your Joomla website, then please contact us and we can fix it for you in as little time and for as little cost as possible!