NAME

       memcached_prepend - Appending to or Prepending Data

SYNOPSIS

       #include <libmemcached-1.0/memcached.h>
              Compile and link with -lmemcached

       memcached_return_t memcached_prepend(memcached_st *ptr, const char *key, size_t key_length, const char
       *value, size_t value_length, time_t expiration, uint32_t flags)

       memcached_return_t memcached_append(memcached_st *ptr, const char *key, size_t key_length, const char
       *value, size_t value_length, time_t expiration, uint32_t flags)

       memcached_return_t memcached_prepend_by_key(memcached_st *ptr, const char *group_key, size_t
       group_key_length, const char *key, size_t key_length, const char *value, size_t value_length, time_t
       expiration, uint32_t flags)

       memcached_return_t memcached_append_by_key(memcached_st *ptr, const char *group_key, size_t
       group_key_length, const char *key, size_t key_length, const char *value, size_t value_length, time_t
       expiration, uint32_t flags)

              Parameters

                     • ptr -- pointer to an initialized memcached_st struct

                     • group_key -- key namespace

                     • group_key_length -- length of the key namespace without any terminating zero

                     • key -- the key

                     • key_length -- length of the key without any terminating zero

                     • value -- the value to append/prepend

                     • value_length -- the length of the value without any terminating zero

                     • expiration -- expiration as a unix timestamp or as relative expiration time in seconds

                     • flags -- 16 bit flags

              Returns
                     memcached_return_t indicating success

DESCRIPTION

       memcached_prepend()  and  memcached_append are used to modify information on a server. All methods take a
       key, and key_length to store the object. Keys are currently limited to 250 characters when using either a
       version of memcached which is 1.4 or below, or when using the text protocol. You must supply both a value
       and a length. Optionally you may set an expiration time for the object and a 16 bit value (it is meant to
       be used as a bitmap). flags is a 4 byte space that is stored along the main  value.  Many  sub  libraries
       make use of this field, so in most cases users should avoid making use of it.

       memcached_prepend()  places  a segment of data before the last piece of data stored. Currently expiration
       and key are not used in the server.

       memcached_append() places a segment of data at the end of  the  last  piece  of  data  stored.  Currently
       expiration and key are not used in the server.

       memcached_prepend_by_key()  and  memcached_append_by_key() methods both behave in a similar manner as the
       non key methods. The difference is that they use their group_key parameter to map objects  to  particular
       servers.

       If you are looking for performance, memcached_set() with non-blocking IO is the fastest way to store data
       on the server.

       All of the above functions are tested with the MEMCACHED_BEHAVIOR_USE_UDP behavior enabled. However, when
       using  these  operations with this behavior on, there are limits to the size of the payload being sent to
       the server.  The reason for these limits is that the  Memcached  Server  does  not  allow  multi-datagram
       requests  and  the  current  server  implementation  sets  a datagram size to 1400 bytes. Due to protocol
       overhead, the actual limit of the user supplied data is less than 1400 bytes and depends on the  protocol
       in   use   as,   well   as  the  operation  being  executed.  When  running  with  the  binary  protocol,
       MEMCACHED_BEHAVIOR_BINARY_PROTOCOL, the size of the key,value, flags and expiry combined may  not  exceed
       1368  bytes. When running with the ASCII protocol, the exact limit fluctuates depending on which function
       is being executed and whether the function is a cas operation or not. For non-cas ASCII  set  operations,
       there  are  at  least  1335  bytes available to split among the key, key_prefix, and value; for cas ASCII
       operations there are at least 1318 bytes available to split among the key, key_prefix and value.  If  the
       total  size  of  the  command,  including overhead, exceeds 1400 bytes, a MEMCACHED_WRITE_FAILURE will be
       returned.

RETURN VALUE

       All methods return a value of type memcached_return_t. On success the value will be MEMCACHED_SUCCESS.

       Use memcached_strerror() to translate this value to a printable string.

SEE ALSO

       memcached(1) libmemcached(3)  memcached_strerror(3)  memcached_set(3)  memcached_add(3)  memcached_cas(3)
       memcached_replace(3)

1.1                                               Mar 31, 2024                              MEMCACHED_PREPEND(3)