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 193   <div class="section" id="appending-or-prepending-data">
 194 <h1>Appending or Prepending Data<a class="headerlink" href="#appending-or-prepending-data" title="Permalink to this headline">¶</a></h1>
 195 <div class="section" id="synopsis">
 196 <h2>SYNOPSIS<a class="headerlink" href="#synopsis" title="Permalink to this headline">¶</a></h2>
 197 <dl class="simple">
 198 <dt>#include &lt;libmemcached-1.0/memcached.h&gt;</dt><dd><p>Compile and link with -lmemcached</p>
 199 </dd>
 200 </dl>
 201 <dl class="function">
 202 <dt id="_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t">
 203 <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>
 204 <dd></dd></dl>
 205
 206 <dl class="function">
 207 <dt id="_CPPv416memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t">
 208 <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>
 209 <dd></dd></dl>
 210
 211 <dl class="function">
 212 <dt id="_CPPv424memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t">
 213 <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>
 214 <dd></dd></dl>
 215
 216 <dl class="function">
 217 <dt id="_CPPv423memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t">
 218 <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>
 219 <dd></dd></dl>
 220
 221 </div>
 222 <div class="section" id="description">
 223 <h2>DESCRIPTION<a class="headerlink" href="#description" title="Permalink to this headline">¶</a></h2>
 224 <p><a class="reference internal" href="#_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_prepend"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">memcached_prepend()</span></code></a> and memcached_append are used to modify information on a
 225 server. All methods take a <code class="docutils literal notranslate"><span class="pre">key</span></code>, and <code class="docutils literal notranslate"><span class="pre">key_length</span></code> to store the object. Keys
 226 are currently limited to 250 characters when using either a version of memcached
 227 which is 1.4 or below, or when using the text protocol. You must supply both a
 228 value and a length. Optionally you may test an expiration time for the object
 229 and a 16 byte value (it is meant to be used as a bitmap). <code class="docutils literal notranslate"><span class="pre">flags</span></code> is a 4byte
 230 space that is stored alongside of the main value. Many sub libraries make use of
 231 this field, so in most cases users should avoid making use of it.</p>
 232 <p><a class="reference internal" href="#_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_prepend"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">memcached_prepend()</span></code></a> places a segment of data before the last piece of data
 233 stored. Currently expiration and key are not used in the server.</p>
 234 <p><a class="reference internal" href="#_CPPv416memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_append"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">memcached_append()</span></code></a> places a segment of data at the end of the last piece of data
 235 stored. Currently expiration and key are not used in the server.</p>
 236 <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-any docutils literal notranslate"><span class="pre">memcached_prepend_by_key()</span></code></a> and <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-any docutils literal notranslate"><span class="pre">memcached_append_by_key()</span></code></a> methods both behave in
 237 a similar method as the non key methods. The difference is that they use their
 238 group_key parameter to map objects to particular servers.</p>
 239 <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-any docutils literal notranslate"><span class="pre">memcached_set()</span></code></a> with non-blocking IO is the
 240 fastest way to store data on the server.</p>
 241 <p>All of the above functions are tested with the <code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_BEHAVIOR_USE_UDP</span></code>
 242 behavior enabled. However, when using these operations with this behavior on,
 243 there are limits to the size of the payload being sent to the server.  The
 244 reason for these limits is that the Memcached Server does not allow
 245 multi-datagram requests and the current server implementation sets a datagram
 246 size to 1400 bytes. Due to protocol overhead, the actual limit of the user
 247 supplied data is less than 1400 bytes and depends on the protocol in use as,
 248 well as the operation being executed. When running with the binary protocol,
 249 <code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_BEHAVIOR_BINARY_PROTOCOL</span></code>, the size of the key,value, flags and
 250 expiry combined may not exceed 1368 bytes. When running with the ASCII protocol,
 251 the exact limit fluctuates depending on which function is being executed and
 252 whether the function is a cas operation or not. For non-cas ASCII set
 253 operations, there are at least 1335 bytes available to split among the key,
 254 key_prefix, and value; for cas ASCII operations there are at least 1318 bytes
 255 available to split among the key, key_prefix and value. If the total size of the
 256 command, including overhead, exceeds 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>
 257 will be returned.</p>
 258 </div>
 259 <div class="section" id="return-value">
 260 <h2>RETURN VALUE<a class="headerlink" href="#return-value" title="Permalink to this headline">¶</a></h2>
 261 <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-any docutils literal notranslate"><span class="pre">memcached_return_t</span></code></a>. On success the value
 262 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>.</p>
 263 <p>Use <a class="reference internal" href="memcached_strerror.html#_CPPv418memcached_strerrorP12memcached_st18memcached_return_t" title="memcached_strerror"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">memcached_strerror()</span></code></a> to translate this value to a printable string.</p>
 264 </div>
 265 <div class="section" id="see-also">
 266 <h2>SEE ALSO<a class="headerlink" href="#see-also" title="Permalink to this headline">¶</a></h2>
 267 <ul class="simple">
 268 <li><p><em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man1/memcached.1.html">memcached(1)</a></em></p></li>
 269 <li><p><a class="reference internal" href="../libmemcached.html"><span class="doc">C/C++ Client Library for memcached</span></a></p></li>
 270 <li><p><a class="reference internal" href="memcached_set.html"><span class="doc">Storing data on the server</span></a></p></li>
 271 <li><p><a class="reference internal" href="memcached_cas.html"><span class="doc">Working with data on the server in an atomic fashion</span></a></p></li>
 272 <li><p><a class="reference internal" href="memcached_strerror.html"><span class="doc">Converting Error Codes to Messages</span></a></p></li>
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