Its effect is to invalidate all existing items immediately (by default) or after the expiration specified. After invalidation none of the items will be returned in response to a retrieval command (unless it's stored again under the same key after flush_all has invalidated the items).

The most precise definition of what flush_all does is the following: it causes all items whose update time is earlier than the time at which flush_all was set to be executed to be ignored for retrieval purposes.

The intent of flush_all with a delay, was that in a setting where you have a pool of memcached servers, and you need to flush all content, you have the option of not resetting all memcached servers at the same time (which could e.g. cause a spike in database load with all clients suddenly needing to recreate content that would otherwise have been found in the memcached daemon).

ENVIRONMENT

MEMCACHED_SERVERS: Specify a list of servers.

NOTES

PROGRAM PREFIX

The prefix of this program is variable, i.e. it can be configured at build time.

Usually the client programs of libmemcached-awesome are prefixed with mem, like memcat or memcp.

It can be configured, though, to replace the prefix with something else like mc, in case of that, the client programs of libmemcached-awesome would be called mccat, mccp, etc. respectively.