db.runCommand(
{ mapreduce : <span><span>collection</span>></span>,
map : <span>mapfunction</span>>,
reduce : <span>reducefunction</span>>
[, query : <span>query</span><span>filter</span><span>object</span>>]
[, sort : <span>sort</span><span>the</span><span>query.</span><span>useful</span><span>for</span><span>optimization</span>>]
[, limit : <span>number</span><span>of</span><span>objects</span><span>to</span><span>return</span><span>from</span><span>collection</span>>]
[, out : <span>output-collection</span><span>name</span>>]
[, keeptemp: <span>true|false</span>>]
[, finalize : <span>finalizefunction</span>>]
[, scope : <span>object</span><span>where</span><span>fields</span><span>go</span><span>into</span><span>javascript</span><span>global</span><span>scope</span> >]
[, verbose : true]
}
);<br><p>参数说明:</p><p>mapreduce:要操作的目标集合</p><p>map:映射函数(生成键值对序列,作为Reduce函数的参数) </p><p>reduce:统计函数</p><p>query:目标记录过滤</p><p><span>立即学习</span>“<a href="https://pan.quark.cn/s/7fc7563c4182" style="text-decoration: underline !important; color: blue; font-weight: bolder;" rel="nofollow" target="_blank">PHP免费学习笔记(深入)</a>”;</p><p>sort:对目标记录排序</p><p>limit:限制目标记录数量</p><div class="aritcle_card flexRow">
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</div><p>out:统计结果存放集合(如果不指定则使用临时集合,在客户端断开后自动删除)</p><p>keeptemp:是否保留临时集合</p><p>finalize:最终处理函数(对reduce返回结果执行最终整理后存入结果集合)</p><p>scope:向map、reduce、finalize导入外部变量</p><p>verbose:显示详细的时间统计信息</p><br><divhelvetica neue yahei background-color:rgb><span><spanlucida grande ms line-height:20px>map函数</spanlucida></span> <br><spanlucida grande ms line-height:20px>map函数调用当前对象,并处里对象的属性,传值给reduce,map方法使用this来操作当前对象,最少调用一次emit(key,value)方法来向reduce提供参数,其中emit的key为最终数据的id。 <br><divhelvetica neue yahei background-color:rgb><span><spanlucida grande ms line-height:20px></spanlucida></span><divhelvetica neue yahei background-color:rgb><span><spanlucida grande ms line-height:20px>reduce函数 <br>接收一个值和数组,根据需要对数组进行合并分组等处理,reduce的key就是emit(key,value)的key,value_array是同个key对应的多个value数组。 <br></spanlucida></span><divhelvetica neue yahei background-color:rgb><span><spanlucida grande ms line-height:20px></spanlucida></span><divhelvetica neue yahei background-color:rgb><span><spanlucida grande ms line-height:20px>Finalize函数 <br>此函数为可选函数,可在执行完map和reduce后执行,对最后的数据进行统一处理。 <br></spanlucida></span><divhelvetica neue yahei background-color:rgb>看完基本介绍,我们再来看一个实例:<divhelvetica neue yahei background-color:rgb>已知集合feed,测试数据如下:<divhelvetica neue yahei background-color:rgb><pre class="brush:php;toolbar:false;" courier new margin-top:0px margin-bottom:1.5em font-size:13px line-height:1.5em word-break:break-all word-wrap:break-word white-space:pre-wrap overflow-y:auto background-color:rgb>{
"<span>_id</span>": <span>ObjectId(<span>"50ccb3f91e937e2927000004"</span>)</span>,
"<span>feed_type</span>": <span><span>1</span></span>,
"<span>to_user</span>": <span><span>234</span></span>,
"<span>time_line</span>": <span><span>"2012-12-16 01:26:00"</span>
}</span>{
"<span>_id</span>": <span>ObjectId(<span>"50ccb3ef1e937e0727000004"</span>)</span>,
"<span>feed_type</span>": <span><span>8</span></span>,
"<span>to_user</span>": <span><span>123</span></span>,
"<span>time_line</span>": <span><span>"2012-12-16 01:26:00"</span>
}</span>{
"<span>_id</span>": <span>ObjectId(<span>"50ccb3e31e937e0a27000003"</span>)</span>,
"<span>feed_type</span>": <span><span>1</span></span>,
"<span>to_user</span>": <span><span>123</span></span>,
"<span>time_line</span>": <span><span>"2012-12-16 01:26:00"</span>
}</span>{
"<span>_id</span>": <span>ObjectId(<span>"50ccb3d31e937e0927000001"</span>)</span>,
"<span>feed_type</span>": <span><span>1</span></span>,
"<span>to_user</span>": <span><span>123</span></span>,
"<span>time_line</span>": <span><span>"2012-12-16 01:26:00"</span>
}</span><br>我们按动态类型feed_type和用户to_user进行分组统计,实现结果:<divhelvetica neue yahei background-color:rgb><table border="1" cellspacing="1" cellpadding="1" align="left"><tbody>
<tr>
<td>feed_type</td>
<td>to_user</td>
<td>cout</td>
</tr>
<tr>
<td>1</td>
<td>234</td>
<td>1</td>
</tr>
<tr>
<td>8</td>
<td>123</td>
<td>1</td>
</tr>
<tr>
<td>1</td>
<td>123</td>
<td>2</td>
</tr>
</tbody></table>
<br><divhelvetica neue yahei background-color:rgb><br><divhelvetica neue yahei background-color:rgb><br><divhelvetica neue yahei background-color:rgb><br><divhelvetica neue yahei background-color:rgb><br><divhelvetica neue yahei background-color:rgb><br><divhelvetica neue yahei background-color:rgb><br><divhelvetica neue yahei background-color:rgb>实现代码:<divhelvetica neue yahei background-color:rgb><pre class="brush:php;toolbar:false;" courier new margin-top:0px margin-bottom:1.5em font-size:13px line-height:1.5em word-break:break-all word-wrap:break-word white-space:pre-wrap overflow-y:auto background-color:rgb><span>//编写map函数</span><span>$map</span> = <span>'
function() {
<span></span> var key = {to_user:this.to_user,feed_type:this.feed_type};
<span></span> var value = {count:1};
<span></span> emit(key,value);
} '</span>;
<span>//reduce 函数</span><span>$reduce</span> = <span>'
function(key, values) {
var ret = {count:0};
<span></span> for(var i in values) {
<span></span> ret.count += 1;
<span></span> }
<span></span> return ret;
}'</span>;
<span>//查询条件</span><span>$query</span> = <span>null</span>; <span>//本实例中没有查询条件,设置为null</span><pre class="brush:php;toolbar:false;" courier new margin-top:0px margin-bottom:1.5em font-size:13px line-height:1.5em word-break:break-all word-wrap:break-word white-space:pre-wrap overflow-y:auto background-color:rgb><span>$mongo</span> = <span>new</span> Mongo(<span>'mongodb://root:root@127.0.0.1: 28017/'</span>); <span>//链接mongodb,账号和密码为root,root</span><span>$instance</span> = <span>$mongo</span>->selectDB(<span>"testdb"</span>);
<span>//执行此命令后,会创建feed_temp_res的临时集合,并将统计后的数据放在该集合中</span><span>$cmd</span> = <span>$instance</span>->command(<span>array</span>(
<span></span><span></span><span>'mapreduce'</span> => <span>'feed'</span>,
<span></span><span></span><span>'map'</span> => <span>$map</span>,
<span></span><span></span><span>'reduce'</span> => <span>$reduce</span>,
<span></span><span></span><span>'query'</span> => <span>$query</span>,
<span></span><span></span><span>'out'</span> => <span>'feed_temp_res'</span>
));
<span>//查询临时集合中的统计数据,验证统计结果是否和预期结果一致</span><span>$cursor</span> = <span>$instance</span>->selectCollection(<span>'feed_temp_res'</span>)->find();
<span>$result</span> = <span>array</span>();
<span>try</span> {
<span></span><span>while</span> (<span>$cursor</span>->hasNext())
<span></span>{
<span></span><span></span><span>$result</span>[] = <span>$cursor</span>->getNext();
<span></span>}
}
<span>catch</span> (MongoConnectionException <span>$e</span>)
{
<span></span><span>echo</span><span>$e</span>->getMessage();
}
<span>catch</span> (MongoCursorTimeoutException <span>$e</span>)
{
<span></span><span>echo</span><span>$e</span>->getMessage();
}
<span>catch</span>(<span>Exception</span><span>$e</span>){
<span></span><span>echo</span><span>$e</span>->getMessage();
}
<span>//test</span>
var_dump(<span>$result</span>);<br>下面是输出的结果,和预期结果一致<divhelvetica neue yahei background-color:rgb><pre class="brush:php;toolbar:false;" courier new margin-top:0px margin-bottom:1.5em font-size:13px line-height:1.5em word-break:break-all word-wrap:break-word white-space:pre-wrap overflow-y:auto background-color:rgb>{
"<span>_id</span>": <span>{
"<span>to_user</span>": <span><span>234</span></span>,
"<span>feed_type</span>": <span><span>1</span> }</span></span>,
"<span>value</span>": <span>{
"<span>count</span>": <span><span>1</span> }</span>}</span>{
"<span>_id</span>": <span>{
"<span>to_user</span>": <span><span>123</span></span>,
"<span>feed_type</span>": <span><span>8</span> }</span></span>,
"<span>value</span>": <span>{
"<span>count</span>": <span><span>1</span> }</span>}</span>{
"<span>_id</span>": <span>{
"<span>to_user</span>": <span><span>123</span></span>,
"<span>feed_type</span>": <span><span>1</span> }</span></span>,
"<span>value</span>": <span>{
"<span>count</span>": <span><span>2</span> }</span>}</span><br><divhelvetica neue yahei background-color:rgb>以上只是简单的统计实现,你可以实现复杂的条件统计编写复杂的reduce函数,可以增加查询条件,排序等等。<divhelvetica neue yahei background-color:rgb>附上mapReduce数据库处理函数(简单封装)<divhelvetica neue yahei background-color:rgb><pre class="brush:php;toolbar:false;" courier new margin-top:0px margin-bottom:1.5em font-size:13px line-height:1.5em word-break:break-all word-wrap:break-word white-space:pre-wrap overflow-y:auto background-color:rgb>/<span>**</span>
* mapReduce分组
*
* <span>@param</span> string <span>$table_name</span> 表名(要操作的目标集合名)
* <span>@param</span> string <span>$map</span> 映射函数(生成键值对序列,作为 reduce 函数参数)
* <span>@param</span> string <span>$reduce</span> 统计处理函数
* <span>@param</span> array <span>$query</span> 过滤条件 如:array(<span>'uid'</span>=><span>123</span>)
* <span>@param</span> array <span>$sort</span> 排序
* <span>@param</span> number <span>$limit</span> 限制的目标记录数
* <span>@param</span> string <span>$out</span> 统计结果存放集合 (不指定则使用tmp_mr_res<span>_</span><span>$table_name</span>, <span>1.8</span>以上版本需指定)
* <span>@param</span> bool <span>$keeptemp</span> 是否保留临时集合
* <span>@param</span> string <span>$finalize</span> 最终处理函数 (对reduce返回结果进行最终整理后存入结果集合)
* <span>@param</span> string <span>$scope</span> 向 <span>map</span>、reduce、finalize 导入外部js变量
* <span>@param</span> bool <span>$jsMode</span> 是否减少执行过程中BSON和JS的转换,默认true(注:false时 BSON-->JS-->map-->BSON-->JS-->reduce-->BSON,可处理非常大的mapreduce,<span>//true</span>时BSON-->js-->map-->reduce-->BSON)
* <span>@param</span> bool <span>$verbose</span> 是否产生更加详细的服务器日志
* <span>@param</span> bool <span>$returnresult</span> 是否返回新的结果集
* <span>@param</span> array &<span>$cmdresult</span> 返回mp命令执行结果 array(<span>"errmsg"</span>=><span>""</span>,<span>"code"</span>=><span>13606</span>,<span>"ok"</span>=><span>0</span>) ok=<span>1</span>表示执行命令成功
* <span>@return</span><span>*/</span>
function mapReduce(<span>$table_name</span>,<span>$map</span>,<span>$reduce</span>,<span>$query</span>=null,<span>$sort</span>=null,<span>$limit</span>=<span>0</span>,<span>$out</span>=<span>''</span>,<span>$keeptemp</span>=true,<span>$finalize</span>=null,<span>$scope</span>=null,<span>$jsMode</span>=true,<span>$verbose</span>=true,<span>$returnresult</span>=true,&<span>$cmdresult</span>){
<span>if</span>(empty(<span>$table_name</span>) || empty(<span>$map</span>) || empty(<span>$reduce</span>)){
<span>return</span> null;
}
<span>$map</span> = new MongoCode(<span>$map</span>);
<span>$reduce</span> = new MongoCode(<span>$reduce</span>);
<span>if</span>(empty(<span>$out</span>)){
<span>$out</span> = <span>'tmp_mr_res_'</span>.<span>$table_name</span>;
}
<span>$cmd</span> = array(
<span>'mapreduce'</span> => <span>$table_name</span>,
<span>'map'</span> => <span>$map</span>,
<span>'reduce'</span> => <span>$reduce</span>,
<span>'out'</span> =><span>$out</span>
);
<span>if</span>(!empty(<span>$query</span>) && is_array(<span>$query</span>)){
array_push(<span>$cmd</span>, array(<span>'query'</span>=><span>$query</span>));
}
<span>if</span>(!empty(<span>$sort</span>) && is_array(<span>$sort</span>)){
array_push(<span>$cmd</span>, array(<span>'sort'</span>=><span>$query</span>));
}
<span>if</span>(!empty(<span>$limit</span>) && is_int(<span>$limit</span>) && <span>$limit</span>><span>0</span>){
array_push(<span>$cmd</span>, array(<span>'limit'</span>=><span>$limit</span>));
}
<span>if</span>(!empty(<span>$keeptemp</span>) && is_bool(<span>$keeptemp</span>)){
array_push(<span>$cmd</span>, array(<span>'keeptemp'</span>=><span>$keeptemp</span>));
}
<span>if</span>(!empty(<span>$finalize</span>)){
<span>$finalize</span> = new Mongocode(<span>$finalize</span>);
array_push(<span>$cmd</span>, array(<span>'finalize'</span>=><span>$finalize</span>));
}
<span>if</span>(!empty(<span>$scope</span>)){
array_push(<span>$cmd</span>, array(<span>'scope'</span>=><span>$scope</span>));
}
<span>if</span>(!empty(<span>$jsMode</span>) && is_bool(<span>$jsMode</span>)){
array_push(<span>$cmd</span>, array(<span>'jsMode'</span>=><span>$jsMode</span>));
}
<span>if</span>(!empty(<span>$verbose</span>) && is_bool(<span>$verbose</span>)){
array_push(<span>$cmd</span>, array(<span>'verbose'</span>=><span>$verbose</span>));
}
<span>$dbname</span> = <span>$this</span>->curr_db_name;
<span>$cmdresult</span> = <span>$this</span>->mongo-><span>$dbname</span>->command(<span>$cmd</span>);
<span>if</span>(<span>$returnresult</span>){
<span>if</span>(<span>$cmdresult</span> && <span>$cmdresult</span>[<span>'ok'</span>]==<span>1</span>){
<span>$result</span> = <span>$this</span>->find(<span>$out</span>, array());
}
}
<span>if</span>(<span>$keeptemp</span>==false){
<span>//</span>删除集合
<span>$this</span>->mongo-><span>$dbname</span>->dropCollection(<span>$out</span>);
}
<span>return</span><span>$result</span>;
}<br><divhelvetica neue yahei background-color:rgb>MongoDB官方网站介绍:<divhelvetica neue yahei background-color:rgb>MapReduce介绍 http://docs.mongodb.org/manual/core/map-reduce/<divhelvetica neue yahei background-color:rgb>Aggregation介绍 http://docs.mongodb.org/manual/aggregation/
<p>
以上就介绍了mongodb的mapreduce用法及php示例代码,包括了方面的内容,希望对PHP教程有兴趣的朋友有所帮助。</p>
<p>
</p>
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