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.TH "MEMCACHED_CAS_BY_KEY" "3" "September 16, 2012" "1.0.10" "libmemcached"
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memcached_cas_by_key \- Storing and Replacing Data
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.\" Man page generated from reStructeredText.
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#include <libmemcached/memcached.h>
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.B memcached_return_t memcached_cas(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, uint64_t\fI\ cas\fP)
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.B memcached_return_t memcached_cas_by_key(memcached_st\fI\ *ptr\fP, const char\fI\ *group_key\fP, size_t\fI\ group_key_length\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, uint64_t\fI\ cas\fP)
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Compile and link with \-lmemcached
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\fI\%memcached_cas()\fP overwrites data in the server as long as the "cas"
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value is still the same in the server. You can get the cas value of a result
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by calling \fBmemcached_result_cas()\fP on a memcached_result_st(3)
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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
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\fBmemcached_set()\fP for information on how to do this.
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\fI\%memcached_cas_by_key()\fP method behaves in a similar method as the non
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key methods. The difference is that it uses the group_key parameter
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to map objects to particular servers.
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\fI\%memcached_cas()\fP is testsed with the \fBMEMCACHED_BEHAVIOR_USE_UDP\fP behavior enabled. However, when using these operations with this behavior
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on, there are limits to the size of the payload being sent to the server. The
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reason for these limits is that the Memcached Server does not allow
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multi\-datagram requests and the current server implementation sets a datagram
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size to 1400 bytes. Due to protocol overhead, the actual limit of the user
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supplied data is less than 1400 bytes and depends on the protocol in use as,
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well as the operation being executed. When running with the binary protocol,
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\fBMEMCACHED_BEHAVIOR_BINARY_PROTOCOL\fP, the size of the key,value,
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flags and expiry combined may not exceed 1368 bytes. When running with the
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ASCII protocol, the exact limit fluctuates depending on which function is
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being executed and whether the function is a cas operation or not. For
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non\-cas ASCII set operations, there are at least 1335 bytes available to
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split among the key, key_prefix, and value; for cas ASCII operations there
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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 \fBMEMCACHED_WRITE_FAILURE\fP will be returned.
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All methods return a value of type \fBmemcached_return_t\fP.
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On success the value will be \fBMEMCACHED_SUCCESS\fP.
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Use \fBmemcached_strerror()\fP to translate this value to a printable
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To find out more information please check:
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\fI\%http://libmemcached.org/\fP
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\fImemcached(1)\fP \fIlibmemached(3)\fP \fImemcached_strerror(3)\fP \fImemcached_set(3)\fP \fImemcached_append(3)\fP \fImemcached_add(3)\fP \fImemcached_prepend(3)\fP \fImemcached_replace(3)\fP
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2011-2012, Brian Aker DataDifferential, http://datadifferential.com/
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