Memcache : increase all keys expiration date

Question

I've been looking around for a way to increase the expiration date for all keys stored in a memcached instance.

The reasoning behind that is simple : I have memcache caching results from DB queries for a period of 300 seconds. I sometimes need to perform DB operations that requires me to shut down the MySQL instance for a couple minutes. To achieve that i usually look up to my configuration file and increase the "lifetime" setting for memcache to 24hours, then let some time pass and shut down mysql. My problem is that some of the items that were stored for 300seconds are not re-pulled from the sql DB during those "few minutes" and therefore not cached, and it leads to errors for my end-user.

What i would like to achieve is to tell memcache to increase all currently stored keys' lifetime by a specific amount.

Is that possible?

Thanks.

Answer 1

Advice: Don't, currently you are trying to use memcache as a substitution of your db while your db is down.

Your db should NEVER be down, if you need to do maintenance you should look into having two db servers (master-master) so you can take one of them down, do the maintenance while the other one keeps working.

Memcache is supposed to be use to speed up things, not as a hacky way to solve other problems.

I understand that probably using memcache for this looks like a simple and good idea, but trust me, it is not.