MongoCursor::explain
(PECL mongo >=0.9.2)
MongoCursor::explain — Return an explanation of the query, often useful for optimization and debugging
Description
public array MongoCursor::explain
( void
)
Parameters
This function has no parameters.
Return Values
Returns an explanation of the query.
Examples
Example #1 MongoCursor::explain() example
<?php
$cursor = $collection->find(array("x"=>1), array("y"));
$cursor->sort(array("z" => 1))->limit(4)->skip(5);
var_dump($cursor->explain());
?>
The above example will output something similar to:
array(8) {
["cursor"]=>
string(15) "BtreeCursor x_1"
["startKey"]=>
array(1) {
["x"]=>
int(1)
}
["endKey"]=>
array(1) {
["x"]=>
int(1)
}
["nscanned"]=>
float(4)
["n"]=>
int(4)
["scanAndOrder"]=>
int(1)
["millis"]=>
int(3)
["allPlans"]=>
array(2) {
[0]=>
array(3) {
["cursor"]=>
string(15) "BtreeCursor x_1"
["startKey"]=>
array(1) {
["x"]=>
int(1)
}
["endKey"]=>
array(1) {
["x"]=>
int(1)
}
}
[1]=>
array(3) {
["cursor"]=>
string(11) "BasicCursor"
["startKey"]=>
array(0) {
}
["endKey"]=>
array(0) {
}
}
}
}
Errors/Exceptions
Throws MongoConnectionException if it cannot reach the database.
See Also
MongoDB core docs on » explain.