git.m6w6.name Git - m6w6/libmemcached/blob - docs/man/memcached_replace_by_key.3

   1 .TH "MEMCACHED_REPLACE_BY_KEY" "3" "April 11, 2011" "0.47" "libmemcached"
   2 .SH NAME
   3 memcached_replace_by_key \- Storing and Replacing Data
   4 .
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  32 .
  33 .sp
  34 Store value on server
  35 .SH SYNOPSIS
  36 .sp
  37 #include <libmemcached/memcached.h>
  38 .INDENT 0.0
  39 .TP
  40 .B 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);
  41 .UNINDENT
  42 .INDENT 0.0
  43 .TP
  44 .B 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);
  45 .UNINDENT
  46 .INDENT 0.0
  47 .TP
  48 .B 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);
  49 .UNINDENT
  50 .INDENT 0.0
  51 .TP
  52 .B memcached_return_t memcached_prepend(memcached_st\fI\ *ptr\fP, const char\fI\ *key\fP, size_t\fI\ key_length\fP, const char\fI\ *value\fP, size_t\fI\ value_length\fP, time_t\fI\ expiration\fP, uint32_t\fI\ flags\fP)
  53 .UNINDENT
  54 .INDENT 0.0
  55 .TP
  56 .B memcached_return_t memcached_append(memcached_st\fI\ *ptr\fP, const char\fI\ *key\fP, size_t\fI\ key_length\fP, const char\fI\ *value\fP, size_t\fI\ value_length\fP, time_t\fI\ expiration\fP, uint32_t\fI\ flags\fP)
  57 .UNINDENT
  58 .INDENT 0.0
  59 .TP
  60 .B 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);
  61 .UNINDENT
  62 .INDENT 0.0
  63 .TP
  64 .B 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);
  65 .UNINDENT
  66 .INDENT 0.0
  67 .TP
  68 .B 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);
  69 .UNINDENT
  70 .INDENT 0.0
  71 .TP
  72 .B 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);
  73 .UNINDENT
  74 .INDENT 0.0
  75 .TP
  76 .B 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);
  77 .UNINDENT
  78 .INDENT 0.0
  79 .TP
  80 .B 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);
  81 .UNINDENT
  82 .INDENT 0.0
  83 .TP
  84 .B 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);
  85 .UNINDENT
  86 .sp
  87 Compile and link with \-lmemcached
  88 .SH DESCRIPTION
  89 .sp
  90 memcached_set(), memcached_add(), and memcached_replace() are all used to
  91 store information on the server. All methods take a key, and its length to
  92 store the object. Keys are currently limited to 250 characters by the
  93 memcached(1) server. You must also supply a value and a length. Optionally you
  94 may tests an expiration time for the object and a 16 byte value (it is
  95 meant to be used as a bitmap).
  96 .sp
  97 memcached_set() will write an object to the server. If an object already
  98 exists it will overwrite what is in the server. If the object does not exist
  99 it will be written. If you are using the non\-blocking mode this function
 100 will always return true unless a network error occurs.
 101 .sp
 102 memcached_replace() replaces an object on the server. If the object is not
 103 found on the server an error occurs.
 104 .sp
 105 memcached_add() adds an object to the server. If the object is found on the
 106 server an error occurs, otherwise the value is stored.
 107 .sp
 108 memcached_prepend() places a segment of data before the last piece of data
 109 stored. Currently expiration and key are not used in the server.
 110 .sp
 111 memcached_append() places a segment of data at the end of the last piece of
 112 data stored. Currently expiration and key are not used in the server.
 113 .sp
 114 memcached_cas() overwrites data in the server as long as the "cas" value is
 115 still the same in the server. You can get the cas value of a result by
 116 calling memcached_result_cas() on a memcached_result_st(3) structure. At the point
 117 that this note was written cas is still buggy in memached. Turning on tests
 118 for it in libmemcached(3) is optional. Please see memcached_set() for
 119 information on how to do this.
 120 .sp
 121 memcached_set_by_key(), memcached_add_by_key(), memcached_replace_by_key(),
 122 memcached_prepend_by_key(), memcached_append_by_key_by_key(),
 123 memcached_cas_by_key() methods all behave in a similar method as the non key
 124 methods. The difference is that they use their master_key parameter to map
 125 objects to particular servers.
 126 .sp
 127 If you are looking for performance, memcached_set() with non\-blocking IO is
 128 the fastest way to store data on the server.
 129 .sp
 130 All of the above functions are testsed with the \fBMEMCACHED_BEHAVIOR_USE_UDP\fPbehavior enabled. But when using these operations with this behavior on, there
 131 are limits to the size of the payload being sent to the server.  The reason for
 132 these limits is that the Memcahed Server does not allow multi\-datagram requests
 133 and the current server implementation sets a datagram size to 1400 bytes. Due
 134 to protocol overhead, the actual limit of the user supplied data is less than
 135 1400 bytes and depends on the protocol in use as well as the operation being
 136 executed. When running with the binary protocol, \(ga\(ga MEMCACHED_BEHAVIOR_BINARY_PROTOCOL\(ga\(ga,
 137 the size of the key,value, flags and expiry combined may not exceed 1368 bytes.
 138 When running with the ASCII protocol, the exact limit fluctuates depending on
 139 which function is being executed and whether the function is a cas operation
 140 or not. For non\-cas ASCII set operations, there are at least 1335 bytes available
 141 to split among the key, key_prefix, and value; for cas ASCII operations there are
 142 at least 1318 bytes available to split among the key, key_prefix and value. If the
 143 total size of the command, including overhead, exceeds 1400 bytes, a \fBMEMCACHED_WRITE_FAILURE\fPwill be returned.
 144 .SH RETURN
 145 .sp
 146 All methods return a value of type \fBmemcached_return_t\fP.
 147 On success the value will be \fBMEMCACHED_SUCCESS\fP.
 148 Use memcached_strerror() to translate this value to a printable string.
 149 .sp
 150 For memcached_replace() and memcached_add(), \fBMEMCACHED_NOTSTORED\fP is a
 151 legitmate error in the case of a collision.
 152 .SH HOME
 153 .sp
 154 To find out more information please check:
 155 \fI\%https://launchpad.net/libmemcached\fP
 156 .SH SEE ALSO
 157 .sp
 158 memcached(1) libmemached(3) memcached_strerror(3)
 159 .SH AUTHOR
 160 Brian Aker
 161 .SH COPYRIGHT
 162 2011, Brian Aker DataDifferential, http://datadifferential.com/
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