NAME¶
memcached_append - Appending to or Prepending to data on the server
Appending or Prepending to data on the server
SYNOPSIS¶
#include <libmemcached/memcached.h>
- 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)
Compile and link with -lmemcached
DESCRIPTION¶
memcached_prepend() and memcached_append are used to modify information
on a server. All methods take a key, and its 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 test an expiration time
for the object and a 16 byte value (it is meant to be used as a bitmap).
"flags" is a 4byte space that is stored alongside of 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 method 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 testsed 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¶
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.
HOME¶
To find out more information please check:
http://libmemcached.org/
SEE ALSO¶
memcached(1) libmemached(3) memcached_strerror(3)
memcached_set(3) memcached_add(3) memcached_cas(3)
memcached_replace(3)
AUTHOR¶
Brian Aker
COPYRIGHT¶
2011-2013, Brian Aker DataDifferential,
http://datadifferential.com/