(PECL mongo >=0.9.2)
MongoDB::command — Execute a database command
$command
[, array $options = array()
] )Almost everything that is not a CRUD operation can be done with a database command. Need to know the database version? There's a command for that. Need to do aggregation? There's a command for that. Need to turn up logging? You get the idea.
This method is identical to:
<?php
public function command($data) {
return $this->selectCollection('$cmd')->findOne($data);
}
?>
command
The query to send.
options
This parameter is an associative array of the form array("optionname" => <boolean>, ...). Currently supported options are:
"timeout"
Integer, defaults to Mongo::$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.
| 版本 | 说明 |
|---|---|
| 1.2.0 | Added options parameter with a single option: timeout. |
Returns database response.
Example #1 MongoDB::command() "distinct" example
Finding all of the distinct values for a key.
<?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：
Example #2 MongoDB::command() "distinct" example
Finding all of the distinct values for a key, where the value is larger than or equal to 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：
Example #3 MongoDB::command() MapReduce example
Get all users with at least on "sale" event, and how many times each of these users has had a sale.
<?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：
Note: Using MongoCode
This example uses MongoCode, which can also take a scope argument. However, at the moment, MongoDB does not support using scopes in MapReduce. If you would like to use client-side variables in the MapReduce functions, you can add them to the global scope by using the optional scope field with the database command. See the » MapReduce documentation for more information.
Note: The out argument
Before 1.8.0, the out argument was optional. If you did not use it, MapReduce results would be written to a temporary collection, which would be deleted when your connection was closed. In 1.8.0+, the out argument is required. See the » MapReduce documentation for more information.
If you are going to be using MapReduce, Prajwal Tuladhar created an API for Mongo PHP users which provides a nicer interface than the bare command. You can download it from » Github and there is a » blog post on how to use it.
MongoDB core docs on » database commands and on individual commands: » findAndModify, » getLastError, and » repair (dozens more exist, there are merely a few examples).