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NAME

       memcached_set, memcached_add, memcached_replace - Store value on server

LIBRARY

       C Client Library for memcached (libmemcached, -lmemcached)

SYNOPSIS

         #include <memcached.h>

         memcached_return_t
           memcached_set (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_add (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_replace (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(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_cas(memcached_st *ptr,
                         const char *key, size_t key_length,
                         const char *value, size_t value_length,
                         time_t expiration,
                         uint32_t flags,
                         uint64_t cas);

         memcached_return_t
           memcached_set_by_key(memcached_st *ptr,
                                const char *master_key, size_t master_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_add_by_key(memcached_st *ptr,
                                const char *master_key, size_t master_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_replace_by_key(memcached_st *ptr,
                                    const char *master_key, size_t master_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_prepend_by_key(memcached_st *ptr,
                                    const char *master_key, size_t master_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 *master_key, size_t master_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_cas_by_key(memcached_st *ptr,
                                const char *master_key, size_t master_key_length,
                                const char *key, size_t key_length,
                                const char *value, size_t value_length,
                                time_t expiration,
                                uint32_t flags,
                                uint64_t cas);

DESCRIPTION

       memcached_set(), memcached_add(), and memcached_replace() are all used
       to store information on the server. All methods take a key, and its
       length to store the object. Keys are currently limited to 250
       characters by the memcached(1) server. You must also supply a value and
       a length. Optionally you may support an expiration time for the object
       and a 16 byte value (it is meant to be used as a bitmap).

       memcached_set() will write an object to the server. If an object
       already exists it will overwrite what is in the server. If the object
       does not exist it will be written. If you are using the non-blocking
       mode this function will always return true unless a network error
       occurs.

       memcached_replace() replaces an object on the server. If the object is
       not found on the server an error occurs.

       memcached_add() adds an object to the server. If the object is found on
       the server an error occurs, otherwise the value is stored.

       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_cas() overwrites data in the server as long as the "cas"
       value is still the same in the server. You can get the cas value of a
       result by calling memcached_result_cas() on a memcached_result_st(3)
       structure. At the point that this note was written cas is still buggy
       in memached. Turning on support for it in libmemcached(3) is optional.
       Please see memcached_set() for information on how to do this.

       memcached_set_by_key(), memcached_add_by_key(),
       memcached_replace_by_key(), memcached_prepend_by_key(),
       memcached_append_by_key_by_key(), memcached_cas_by_key() methods all
       behave in a similar method as the non key methods. The difference is
       that they use their master_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 supported with the
       "MEMCACHED_BEHAVIOR_USE_UDP" behavior enabled. But 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 Memcahed 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

       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.

       For memcached_replace() and memcached_add(), "MEMCACHED_NOTSTORED" is a
       legitmate error in the case of a collision.

HOME

       To find out more information please check:
       <https://launchpad.net/libmemcached>

AUTHOR

       Brian Aker, <brian@tangent.org>

SEE ALSO

       memcached(1) libmemached(3) memcached_strerror(3)

                                  2010-01-07          memcached_prepend.pop(3)