(PECL mongo >=1.3.0)
MongoClient::setReadPreference — Ϊ���������ö�ȡѡ��
This extension that defines this method is deprecated. Instead, the MongoDB extension should be used. There is no equivalent for this method in the new extension.
$read_preference
[, array $tags
] ) : boolread_preferenceThe read preference mode: MongoClient::RP_PRIMARY, MongoClient::RP_PRIMARY_PREFERRED, MongoClient::RP_SECONDARY, MongoClient::RP_SECONDARY_PREFERRED, or MongoClient::RP_NEAREST.
tagsAn 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.
Returns TRUE on success, or FALSE otherwise.
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.
Example #1 MongoClient::setReadPreference() ��ǩ�������������
<?php
$m = new MongoClient();
// ��ѡ����� "east" �������ĵķ�������Ҳ���ڱ��棬
// ʧ��ʱ���� "west" �������ĵķ�����
$m->setReadPreference(MongoClient::RP_NEAREST, array(
array('dc' => 'east', 'use' => 'reporting'),
array('dc' => 'west'),
));
?>