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Updated: Thursday, June 13, 2019
 
 

memcached_set_by_key (3libmemcached)

Name

memcached_set_by_key - Storing and Replacing Data

Synopsis

#include <libmemcached/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 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 expi-
ration, 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 expi-
ration, 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 expi-
ration, uint32_t flags)

Compile and link with -lmemcached

Description

libmemcached                               MEMCACHED_SET_BY_KEY(3libmemcached)



NAME
       memcached_set_by_key - Storing and Replacing Data

SYNOPSIS
       #include <libmemcached/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 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 expi-
       ration, 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 expi-
       ration, 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 expi-
       ration, uint32_t flags)

       Compile and link with -lmemcached

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
       libraries 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
       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_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 tests 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(),           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  testsed  with  the  MEMCACHED_BEHAV-
       IOR_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_BEHAV-
       IOR_BINARY_PROTOCOL,  the  size of the key,value, flags and expiry com-
       bined may not exceed 1368 bytes. When running with the ASCII  protocol,
       the  exact  limit  fluctuates depending on which function is being exe-
       cuted 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: http://libmemcached.org/


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+----------------------+
       |ATTRIBUTE TYPE |   ATTRIBUTE VALUE    |
       +---------------+----------------------+
       |Availability   | library/libmemcached |
       +---------------+----------------------+
       |Stability      | Uncommitted          |
       +---------------+----------------------+
SEE ALSO
       memcached(1) libmemached(3) memcached_strerror(3)  memcached_prepend(3)
       memcached_cas(3) memcached_append(3)

AUTHOR
       Brian Aker

COPYRIGHT
       2011-2013, Brian Aker DataDifferential, http://datadifferential.com/



NOTES
       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source     was     downloaded    from     https://launchpad.net/libmem-
       cached/1.0/1.0.18/+download/libmemcached-1.0.18.tar.gz

       Further information about this software can be found on the open source
       community website at http://libmemcached.org/libMemcached.html.



1.0.18                         February 09, 2014
                                           MEMCACHED_SET_BY_KEY(3libmemcached)