Sets whether this query can be done on a secondary

说明

public MongoCursor MongoCursor::slaveOkay ([ bool $okay = true ] )

Calling this will make the driver route reads to secondaries if:

You are using a replica set and
You created a MongoClient instance using the option "replicaSet" => "setName" and
There is a healthy secondary that can be reached by the driver.

You can check which server was used for this query by calling MongoCursor::info() after running the query. It's server field will show which server the query was sent to.

Note that you should use this function even if you do not use the automatic routing to secondaries. If you connect directly to a secondary in a replica set, you still need to call this function, which basically tells the database that you are aware that you might be getting older data and you're okay with that. If you do not call this, you'll get "not master" errors when you try to query.

This method will override the static class variable MongoCursor::$slaveOkay. It will also override Mongo::setSlaveOkay(), MongoDB::setSlaveOkay() and MongoCollection::setSlaveOkay().

参数

okay: If it is okay to query the secondary.

返回值

Returns this cursor.

错误／异常

Throws MongoCursorException if this cursor has started iterating.

范例

Example #1 MongoCursor::slaveOkay() example


<?php

MongoCursor::$slaveOkay = false;

// cannot query secondary
$cursor = $collection->find();

// can query secondary
$cursor = $collection->find()->slaveOkay();

MongoCursor::$slaveOkay = true;

// can query secondary
$cursor = $collection->find();

// cannot query secondary
$cursor = $collection->find()->slaveOkay(false);

?>

参见

Read Preferences
MongoCursor::setReadPreference() - Set the read preference for this query
MongoCursor::getReadPreference() - Get the read preference for this query