MongoDB::command
(PECL mongo >=0.9.2)
MongoDB::command — 执行一条 Mongo 指令
说明
$command
[, array $options = array()
] )几乎所有不属于CRUD操作的事情都可以通过一条“数据库指令”完成。需要知道数据库的版本？有一条指令可以实现。需要进行一次聚合？有一条指令可以实现。想要提高日志级别？有一条指令可以实现。我想你已经领会到了。
该方法等同于：
<?php
public function command ( $data ) {
return $this -> selectCollection ( '$cmd' )-> findOne ( $data );
}
?> 参数
-
command -
要发送的指令
-
options -
该参数是一个具有以下形式的关联数组： array("optionname" => <boolean>, ...)，现在支持的选项有：
-
"timeout"
Integer, defaults to MongoCursor::$timeout. If "safe" is set, this sets how long (in milliseconds) for the client to wait for a database response. If the database does not respond within the timeout period, a MongoCursorTimeoutException will be thrown.
-
更新日志
| 版本 | 说明 |
|---|---|
| 1.2.0 | 添加 options 参数，和一个选项:"timeout"。 |
返回值
返回数据库响应。每个响应都不会超过一个文档的大小，也就是不会超过16MB。 结果文档的结构与执行的指令有关,但大部分结果都有 ok 字段来表示成功还是失败。以及 results 字段包含一个结果文档数组。
范例
Example #1 MongoDB::command() "distinct"实例
查找一个键的所有不重复值
<?php
$people = $db -> people ;
$people -> insert (array( "name" => "Joe" , "age" => 4 ));
$people -> insert (array( "name" => "Sally" , "age" => 22 ));
$people -> insert (array( "name" => "Dave" , "age" => 22 ));
$people -> insert (array( "name" => "Molly" , "age" => 87 ));
$ages = $db -> command (array( "distinct" => "people" , "key" => "age" ));
foreach ( $ages [ 'values' ] as $age ) {
echo " $age \n" ;
}
?> 以上例程的输出类似于：
4
22
87
Example #2 MongoDB::command() "distinct"实例
查找一个键的所有不重复值，并且这些值大于等于18
<?php
$people = $db -> people ;
$people -> insert (array( "name" => "Joe" , "age" => 4 ));
$people -> insert (array( "name" => "Sally" , "age" => 22 ));
$people -> insert (array( "name" => "Dave" , "age" => 22 ));
$people -> insert (array( "name" => "Molly" , "age" => 87 ));
$ages = $db -> command (
array(
"distinct" => "people" ,
"key" => "age" ,
"query" => array( "age" => array( '$gte' => 18 ))
)
);
foreach ( $ages [ 'values' ] as $age ) {
echo " $age \n" ;
}
?> 以上例程的输出类似于：
22
87
Example #3 MongoDB::command() MapReduce实例
获取所有有type=sale这样的"event"的用户，以及他们分别有几个这样的"event"（注:此处的event是一个集合的名字）
<?php
// sample event document
$events -> insert (array( "user_id" => $id ,
"type" => $type ,
"time" => new MongoDate (),
"desc" => $description ));
// construct map and reduce functions
$map = new MongoCode ( "function() { emit(this.user_id,1); }" );
$reduce = new MongoCode ( "function(k, vals) { " .
"var sum = 0;" .
"for (var i in vals) {" .
"sum += vals[i];" .
"}" .
"return sum; }" );
$sales = $db -> command (array(
"mapreduce" => "events" ,
"map" => $map ,
"reduce" => $reduce ,
"query" => array( "type" => "sale" ),
"out" => array( "merge" => "eventCounts" )));
$users = $db -> selectCollection ( $sales [ 'result' ])-> find ();
foreach ( $users as $user ) {
echo " { $user [ '_id' ]} had { $user [ 'value' ]} sale(s).\n" ;
}
?> 以上例程的输出类似于：
User 47cc67093475061e3d9536d2 had 3 sale(s).
User 49902cde5162504500b45c2c had 14 sale(s).
User 4af467e4fd543cce7b0ea8e2 had 1 sale(s).
Note: 使用 MongoCode
这个例子使用了 MongoCode，它还可以接受一个作用域参数。然而，现在 MongoDB 还不支持在 MapReduce 中使用它， 如果你需要在MapReduce函数里用一个客户端参数，那么你可以在使用MapReduce的时候用“optional scope”字段把它们添加到全局作用域中，参考 » MapReduce文档 来获得更多信息。
Note: out 参数
1.8.0以前，out 参数是可选的，如果你不使用它，MapReduce的结果将被写入一个临时集合里，这个临时集合会在连接关闭后删除。 1.8.0以后，out 参数是必须的，参考 » MapReduce documentation 来获得更多信息。
Example #4 MongoDB::command() "textSearch"实例
在MongoDB 2.4以上版本中使用全文检索功能（之前的版本不支持全文检索）。
<?php
$m = new MongoClient ();
$d = $m -> demo ;
$c = $d -> planets ;
$c -> insert (array( "name" => "Mercury" , "desc" => "Mercury is the smallest and closest to the Sun" ));
$c -> insert (array( "name" => "Venus" , "desc" => "Venus is the second planet from the Sun, orbiting it every 224.7 Earth days." ));
$c -> insert (array( "name" => "Earth" , "desc" => "Earth is the the densest of the eight planets in the Solar System." ));
$c -> insert (array( "name" => "Mars" , "desc" => "Mars is named after the Roman god of war." ));
$c -> ensureIndex (array( 'desc' => 'text' ));
$r = $d -> command (array( "text" => "planets" , 'search' => "sun" ));
print_r ( $r );
?> 以上例程的输出类似于：
Array
(
[queryDebugString] => sun||||||
[language] => english
[results] => Array
(
[0] => Array
(
[score] => 0.625
[obj] => Array
(
[_id] => MongoId Object
(
[$id] => 517549d944670a4a5cb3059a
)
[name] => Mercury
[desc] => Mercury is the smallest and closest to the Sun
)
)
[1] => Array
(
[score] => 0.55
[obj] => Array
(
[_id] => MongoId Object
(
[$id] => 517549d944670a4a5cb3059b
)
[name] => Venus
[desc] => Venus is the second planet from the Sun, orbiting it every 224.7 Earth days.
)
)
)
[stats] => Array
(
[nscanned] => 2
[nscannedObjects] => 0
[n] => 2
[nfound] => 2
[timeMicros] => 95
)
[ok] => 1
)
Example #5 MongoDB::command() "geoNear"实例
这个实例说明了如何使用 geoNear 指令。
<?php
$m = new MongoClient ();
$d = $m -> demo ;
$c = $d -> poiConcat ;
$r = $d -> command (array(
'geoNear' => "poiConcat" , // 在 poiConcat 集合中
'near' => array(- 0.08 , 51.48 ), // 搜索 51.48°N, 0.08°E 附近
'spherical' => true , // 启用特殊搜索
'num' => 5 , // 最多返回5个文档
));
print_r ( $r );
?> 参见
- MongoCollection::aggregate() - Perform an aggregation using the aggregation framework
- MongoCollection::findAndModify() - Update a document and return it
- MongoCollection::group() - Performs an operation similar to SQL's GROUP BY command
MongoDB 核心文档的 » 数据库指令 ，以及这些特定指令的文档 » findAndModify、 » getLastError、 » repairDatabase （还有很多其他指令，这只是一些例子）
用户评论:
[#1] nanhe dot kumar at gmail dot com [2013-08-21 21:41:14]
$db=new new Mongo();
Copy old_db to new_db
$responseCopy = $db->admin->command(array(
'copydb' => 1,
'fromhost' => 'localhost',
'fromdb' => 'old_db',
'todb' =>'new_db'
));
Now drop old_db
if($responseCopy['ok']==1){
$responseDrop=$db->old_db->command(array('dropDatabase' => 1));
//OR
$responseDrop =$db->old_db->drop();
}
Show Output
print_r($responseCopy);
print_r($responseDrop);
Output will be something like this
Array ( [ok] => 1 )
Array ( [dropped] => old_db [ok] => 1 )
[#2] mcuadros at gmail dot com [2013-04-09 11:13:54]
Command of Mongo 2.4 Text Search feature.
<?php
$result = $db->command(
array(
'text' => 'bar', //this is the name of the collection where we are searching
'search' => 'hotel', //the string to search
'limit' => 5, //the number of results, by default is 1000
'project' => Array( //the fields to retrieve from db
'title' => 1
)
)
);
[#3] Anonymous [2011-06-08 04:18:10]
> Need to know the database version? There's a command for that.
We didn't find it - ended up using either;
<?php
$m = new Mongo();
$adminDB = $m->admin; //require admin priviledge
$mongodb_info = $adminDB->command(array('buildinfo'=>true));
$mongodb_version = $mongodb_info['version'];
print_r($mongodb_info);
?>
or
<?php
$v = `mongo --version`;
print_r($v);
?>
[#4] roman dot drapeko at gmail dot com [2011-04-16 02:07:08]
I tried to write MapReduce. Unfortunately, out => array('replace' => 'collName') did not work for me. Instead, the below code works
<?php
$mongo->command(array(
'mapreduce' => 'events',
'map' => $map,
'reduce' => $reduce,
'out' => 'mapReduceEventStats'
));
?>
[#5] Min He [2010-07-21 04:31:58]
rename a collection:
<?php
$m = new Mongo();
$adminDB = $m->admin; //require admin priviledge
//rename collection 'colA' in db 'yourdbA' to collection 'colB' in another db 'yourdbB'
$res = $adminDB->command(array(
"renameCollection" => "yourdbA.colA",
"to" => "yourdbB.colB"
));
var_dump($res);
?>