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이 문서에서는 PHP 중국어 웹사이트 매뉴얼 풀어 주다
(PECL mongo >=1.0.4)
MongoCursor::addOption — Adds a top-level key/value pair to a query
$key
, mixed $value
)This is an advanced function and should not be used unless you know what you're doing.
A query can optionally be nested in a "query" field if other options, such as a sort or hint, are given. For instance, adding a sort causes the query to become a subfield of a bigger query object, like:
<?php
$query = array( "query" => $query , "orderby" => $sort );
?>
This method is for adding a top-level field to a query. It makes the query a subobject (if it isn't already) and adds the key/value pair of your chosing to the top level.
It cannot be used to add extra criteria to a query on the fly. For instance, this will not work:
<?php
// NOT CORRECT
$cursor = $users -> find ()-> addOption ( "name" , "joe" )-> addOption ( "age" , 20 );
?>
key
Fieldname to add.
value
Value to add.
Returns this cursor.
Throws MongoCursorException if this cursor has started iterating.
Example #1 Adding a comment with MongoCursor::addOption() example
MongoDB supports special options to be send to the server. The shell uses the _addSpecial option to send a $comment to the server. This comment will show up in the profiling log (for slow queries f.e.). In the PHP driver, you use the MongoCursor::addOption() method.
<?php
$m = new MongoClient ;
$c = $m -> demo -> demo ;
$cursor = $c -> find ();
$cursor -> addOption ( '$comment' , "This comment will show up in the profiling log" );
foreach ( $cursor as $document ) { }
?>
以上例程的输出类似于:
{ "op" : "query", "ns" : "demo.demo", "query" : { "$query" : { }, "$comment" : "This comment will show up in the profiling log" }, "cursorid" : 168463566447, "ntoreturn" : 0, "ntoskip" : 0, "nscanned" : 101, "nscannedObjects" : 101, "keyUpdates" : 0, "numYield" : 0, …
Example #2 MongoCursor::addOption() example
Using MongoCursor::skip() to skip over millions of results can become slow. One way around this is to use $min or $max options for the query. These can be handy, but they require an index on exactly the fields being searched for. This is an example of how to use $min as an alternative to MongoCursor::skip() .
<?php
// make sure we have an index
$c -> ensureIndex (array( "ts" => 1 ));
// you may have to modify this to run in a reasonable amount of time on slow
// machines (should take about 30 seconds on a good machine)
for ( $i = 0 ; $i < 30000000 ; $i ++) {
$c -> insert (array( "ts" => new MongoDate (), "i" => $i ));
}
$now = strtotime ( "now" );
// find documents inserted in the last 2 seconds
$cursor = $c -> find ()-> addOption ( '$min' , array( "ts" => $now - 2 ));
?>