MongoCursor::setReadPreference

Set the read preference for this query

Description

public MongoCursor MongoCursor::setReadPreference ( string $read_preference [, array $tags ] )

Parameters

read_preference: The read preference mode: MongoClient::RP_PRIMARY, MongoClient::RP_PRIMARY_PREFERRED, MongoClient::RP_SECONDARY, MongoClient::RP_SECONDARY_PREFERRED, or MongoClient::RP_NEAREST.
tags: An array of zero or more tag sets, where each tag set is itself an array of criteria used to match tags on replica set members.

Return Values

Returns this cursor.

Errors/Exceptions

Emits E_WARNING if either parameter is invalid, or if one or more tag sets are provided with the MongoClient::RP_PRIMARY read preference mode.

Examples

Example #1 MongoCursor::setReadPreference tag set array syntaxexample


<?php

$m = new MongoClient();
$cursor = $m->test->users->find();

// Prefer the nearest server in the "east" data center also used for reporting,
// but fall back to a server in the "west" data center
$cursor->setReadPreference(MongoClient::RP_NEAREST, array(
    array('dc' => 'east', 'use' => 'reporting'),
    array('dc' => 'west'),
));
?>