MEMCACHED_ADD_BY_KEY(3) libmemcached-awesome MEMCACHED_ADD_BY_KEY(3)
NAME
memcached_add_by_key - Storing and Replacing Data
SYNOPSIS
#include <libmemcached/memcached.h>
Compile and link with -lmemcached
memcached_return_t memcached_set(memcached_st *ptr, const char *key,
size_t key_length, const char *value, size_t value_length, time_t expi-
ration, 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 expi-
ration, 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_set_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_add_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_replace_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)
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 charac-
ters when using either a version of memcached(1) which is 1.4 or below,
or when using the text protocol. You must supply both a value and a
length. Optionally you store the object. Keys are currently limited to
250 characters by the memcached(1) server. 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 li-
braries make use of this field, so in most cases users should avoid
making use of it.
memcached_set() will write an object to the server. If an object al-
ready 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 oc-
curs.
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_set_by_key(), memcached_add_by_key(), and
memcached_replace_by_key() methods all 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 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 avail-
able to split among the key, key_prefix, and value; for cas ASCII oper-
ations there are at least 1318 bytes available to split among the key,
key_prefix and value. If the total size of the command, including over-
head, 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.
For memcached_replace() and memcached_add(), MEMCACHED_NOTSTORED is a
legitimate error in the case of a collision.
SEE ALSO
memcached(1) libmemcached(3) memcached_strerror(3) memcached_prepend(3)
memcached_append(3) memcached_cas(3)
1.1 Mar 06, 2023 MEMCACHED_ADD_BY_KEY(3)
Czas wygenerowania: 0.00027 sek.
Created with the man page lookup class by Andrew Collington.
Based on a C man page viewer by Vadim Pavlov
Unicode soft-hyphen fix (as used by RedHat) by Dan Edwards
Some optimisations by Eli Argon
Caching idea and code contribution by James Richardson
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