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 212 <h1>Appending or Prepending to data on the server<a class="headerlink" href="#appending-or-prepending-to-data-on-the-server" title="Permalink to this headline">¶</a></h1>
 213 <p id="index-0">Appending or Prepending to data on the server</p>
 214 <div class="section" id="synopsis">
 215 <h2>SYNOPSIS<a class="headerlink" href="#synopsis" title="Permalink to this headline">¶</a></h2>
 216 <p>#include &lt;libmemcached/memcached.h&gt;</p>
 217 <dl class="function">
 218 <dt id="_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t">
 219 <span id="_CPPv317memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="_CPPv217memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="memcached_prepend__memcached_stP.cCP.s.cCP.s.time_t.uint32_t"></span><a class="reference internal" href="memcached_return_t.html#_CPPv418memcached_return_t" title="memcached_return_t">memcached_return_t</a> <code class="sig-name descname">memcached_prepend</code><span class="sig-paren">(</span><a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st">memcached_st</a> *<em>ptr</em>, <em class="property">const</em> char *<em>key</em>, size_t <em>key_length</em>, <em class="property">const</em> char *<em>value</em>, size_t <em>value_length</em>, time_t <em>expiration</em>, uint32_t <em>flags</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="Permalink to this definition">¶</a><br /></dt>
 220 <dd></dd></dl>
 221
 222 <dl class="function">
 223 <dt id="_CPPv416memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t">
 224 <span id="_CPPv316memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="_CPPv216memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="memcached_append__memcached_stP.cCP.s.cCP.s.time_t.uint32_t"></span><a class="reference internal" href="memcached_return_t.html#_CPPv418memcached_return_t" title="memcached_return_t">memcached_return_t</a> <code class="sig-name descname">memcached_append</code><span class="sig-paren">(</span><a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st">memcached_st</a> *<em>ptr</em>, <em class="property">const</em> char *<em>key</em>, size_t <em>key_length</em>, <em class="property">const</em> char *<em>value</em>, size_t <em>value_length</em>, time_t <em>expiration</em>, uint32_t <em>flags</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv416memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="Permalink to this definition">¶</a><br /></dt>
 225 <dd></dd></dl>
 226
 227 <dl class="function">
 228 <dt id="_CPPv424memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t">
 229 <span id="_CPPv324memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="_CPPv224memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="memcached_prepend_by_key__memcached_stP.cCP.s.cCP.s.cCP.s.time_t.uint32_t"></span><a class="reference internal" href="memcached_return_t.html#_CPPv418memcached_return_t" title="memcached_return_t">memcached_return_t</a> <code class="sig-name descname">memcached_prepend_by_key</code><span class="sig-paren">(</span><a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st">memcached_st</a> *<em>ptr</em>, <em class="property">const</em> char *<em>group_key</em>, size_t <em>group_key_length</em>, <em class="property">const</em> char *<em>key</em>, size_t <em>key_length</em>, <em class="property">const</em> char *<em>value</em>, size_t <em>value_length</em>, time_t <em>expiration</em>, uint32_t <em>flags</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv424memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t" title="Permalink to this definition">¶</a><br /></dt>
 230 <dd></dd></dl>
 231
 232 <dl class="function">
 233 <dt id="_CPPv423memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t">
 234 <span id="_CPPv323memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="_CPPv223memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="memcached_append_by_key__memcached_stP.cCP.s.cCP.s.cCP.s.time_t.uint32_t"></span><a class="reference internal" href="memcached_return_t.html#_CPPv418memcached_return_t" title="memcached_return_t">memcached_return_t</a> <code class="sig-name descname">memcached_append_by_key</code><span class="sig-paren">(</span><a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st">memcached_st</a> *<em>ptr</em>, <em class="property">const</em> char *<em>group_key</em>, size_t <em>group_key_length</em>, <em class="property">const</em> char *<em>key</em>, size_t <em>key_length</em>, <em class="property">const</em> char *<em>value</em>, size_t <em>value_length</em>, time_t <em>expiration</em>, uint32_t <em>flags</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv423memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t" title="Permalink to this definition">¶</a><br /></dt>
 235 <dd></dd></dl>
 236
 237 <p>Compile and link with -lmemcached</p>
 238 </div>
 239 <div class="section" id="description">
 240 <h2>DESCRIPTION<a class="headerlink" href="#description" title="Permalink to this headline">¶</a></h2>
 241 <p><a class="reference internal" href="#_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_prepend"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_prepend()</span></code></a> and memcached_append are used to
 242 modify information on a server. All methods take a key, and its length to
 243 store the object. Keys are currently limited to 250 characters when using
 244 either a version of memcached which is 1.4 or below, or when using the text
 245 protocol. You must supply both a value and a length. Optionally you
 246 may test an expiration time for the object and a 16 byte value (it is
 247 meant to be used as a bitmap). “flags” is a 4byte space that is stored
 248 alongside of the main value. Many sub libraries make use of this field,
 249 so in most cases users should avoid making use of it.</p>
 250 <p><a class="reference internal" href="#_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_prepend"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_prepend()</span></code></a> places a segment of data before the last piece
 251 of data stored. Currently expiration and key are not used in the server.</p>
 252 <p><a class="reference internal" href="#_CPPv416memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_append"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_append()</span></code></a> places a segment of data at the end of the last
 253 piece of data stored. Currently expiration and key are not used in the server.</p>
 254 <p><a class="reference internal" href="#_CPPv424memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_prepend_by_key"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_prepend_by_key()</span></code></a> and
 255 <a class="reference internal" href="#_CPPv423memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_append_by_key"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_append_by_key()</span></code></a> methods both behave in a similar
 256 method as the non key methods. The difference is that they use their
 257 group_key parameter to map objects to particular servers.</p>
 258 <p>If you are looking for performance, <a class="reference internal" href="memcached_set.html#_CPPv413memcached_setP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_set"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_set()</span></code></a> with non-blocking
 259 IO is the fastest way to store data on the server.</p>
 260 <p>All of the above functions are tested with the
 261 <a class="reference internal" href="memcached_behavior.html#_CPPv4N20memcached_behavior_t26MEMCACHED_BEHAVIOR_USE_UDPE" title="MEMCACHED_BEHAVIOR_USE_UDP"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_BEHAVIOR_USE_UDP</span></code></a> behavior enabled. However, when using
 262 these operations with this behavior on, there are limits to the size of the
 263 payload being sent to the server.  The reason for these limits is that the
 264 Memcached Server does not allow multi-datagram requests
 265 and the current server implementation sets a datagram size to 1400 bytes. Due
 266 to protocol overhead, the actual limit of the user supplied data is less than
 267 1400 bytes and depends on the protocol in use as, well as the operation being
 268 executed. When running with the binary protocol,
 269 <a class="reference internal" href="memcached_behavior.html#_CPPv4N20memcached_behavior_t34MEMCACHED_BEHAVIOR_BINARY_PROTOCOLE" title="MEMCACHED_BEHAVIOR_BINARY_PROTOCOL"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_BEHAVIOR_BINARY_PROTOCOL</span></code></a>, the size of the key,value,
 270 flags and expiry combined may not exceed 1368 bytes. When running with the
 271 ASCII protocol, the exact limit fluctuates depending on which function is
 272 being executed and whether the function is a cas operation or not. For
 273 non-cas ASCII set operations, there are at least 1335 bytes available
 274 to split among the key, key_prefix, and value; for cas ASCII operations
 275 there are at least 1318 bytes available to split among the key, key_prefix
 276 and value. If the total size of the command, including overhead, exceeds
 277 1400 bytes, a <a class="reference internal" href="memcached_return_t.html#_CPPv4N18memcached_return_t23MEMCACHED_WRITE_FAILUREE" title="MEMCACHED_WRITE_FAILURE"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_WRITE_FAILURE</span></code></a> will be returned.</p>
 278 </div>
 279 <div class="section" id="return">
 280 <h2>RETURN<a class="headerlink" href="#return" title="Permalink to this headline">¶</a></h2>
 281 <p>All methods return a value of type <a class="reference internal" href="memcached_return_t.html#_CPPv418memcached_return_t" title="memcached_return_t"><code class="xref cpp cpp-type docutils literal notranslate"><span class="pre">memcached_return_t</span></code></a>.
 282 On success the value will be <a class="reference internal" href="memcached_return_t.html#_CPPv4N18memcached_return_t17MEMCACHED_SUCCESSE" title="MEMCACHED_SUCCESS"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_SUCCESS</span></code></a>.
 283 Use <a class="reference internal" href="memcached_strerror.html#_CPPv418memcached_strerrorP12memcached_st18memcached_return_t" title="memcached_strerror"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_strerror()</span></code></a> to translate this value to a printable
 284 string.</p>
 285 </div>
 286 <div class="section" id="see-also">
 287 <h2>SEE ALSO<a class="headerlink" href="#see-also" title="Permalink to this headline">¶</a></h2>
 288 <p><em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man1/memcached.1.html">memcached(1)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/libmemcached.3.html">libmemcached(3)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/memcached_strerror.3.html">memcached_strerror(3)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/memcached_set.3.html">memcached_set(3)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/memcached_add.3.html">memcached_add(3)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/memcached_cas.3.html">memcached_cas(3)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/memcached_replace.3.html">memcached_replace(3)</a></em></p>
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