What does “invalidated” cache mean in Magento?

Question

In the Magento admin under Cache Management, what does it mean when it shows a cache as invalidated? How does Magento know a cache is invalidated? In particular, I\'m wonderin

Answer 1

The @Magento Guy answer is correct, but I think this solution below can help you on refreshing just the invalidated caches on Magento.

I use Bitnami Magento Stack, for me this solution below was the best I have found.

I've tried to create a Mage_Shell_Class php file, but without success (invalid cache array were always empty when it runs, no matter what, and I really don't imagine why).

I've created a php file 'sample.php':

getCacheInstance()->getInvalidatedTypes();

foreach($invalid as $i)
{
    Mage::app()->getCacheInstance()->cleanType($i["id"]);
}

I've placed it on magento root folder, and to start it I use a cronjob that runs under root user.

So, to create the cronjob on the root user:

sudo crontab -u root -e

And this was my command line to run it:

* * * * * . /opt/bitnami/scripts/setenv.sh ; /opt/bitnami/php/bin/php /opt/bitnami/apps/magento/htdocs/sample.php >> /var/log/cron/cron.log 2>&1

Some parts on this line are very particular to my problem:

1. Since it just refreshes the invalidated caches I've decided to run it every minute.
2. setenv.sh is a script that helps me to set the environment when dealing with this particular bitnami stack.
3. To get the output of this script I used this last part ">> /var/log/cron/cron.log 2>&1" to output errors to a directory that I've created (/var/log/cron), and has given the correct permissions on it.

Probably you need to change the cron line command, but I think this will help you.