Redis

Redis is a big collection of data structures that are held in memory and flushed to disk every so often.

CRUD

$ SET <key>  # set key, update if already exists
$ GET <key>  # get key
$ DEL <key>  # delete key

Expire keys

Expire keys time out after a specified value. IMO it's best to set it in ms rather than seconds to keep compat with unix.

$ PSETEX <key> <timeout> <value>   # set an expiry key in milliseconds
$ SETEX <key> <timeout> <value>    # set an expiry key in seconds