Memcached::append() appends the given
value string to the value of an existing item. The
reason that value is forced to be a string is
that appending mixed types is not well-defined.
Note:
If the Memcached::OPT_COMPRESSION is enabled, the
operation will fail and a warning will be issued, because appending
compressed data to a value that is potentially already compressed is not
possible.
Parameters
key
The key under which to store the value.
value
The string to append.
Return Values
Returns true on success or false on failure.
Returns null when compression is on.
Errors/Exceptions
Returns null and raises an E_WARNING when
compression is enabled.