PHP - Manual: MongoCommandCursor::setReadPreference
2024-12-24
(PECL mongo >=1.6.0)
MongoCommandCursor::setReadPreference — Set the read preference for this command
$read_preference
[, array $tags
] ) : MongoCommandCursorread_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.
Returns this cursor.
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 MongoCommandCursor::setReadPreference() tag set array syntax example
<?php
$m = new MongoClient('mongodb://rs1.example.com:27017', array('replicaSet' => 'myReplSetName'));
$collection = $m->selectCollection('test', 'people');
$cursor = $collection->aggregateCursor( [
[ '$group' => [ '_id' => '$name', 'points' => [ '$sum' => '$points' ] ] ],
[ '$sort' => [ 'points' => -1 ] ],
] );
// Prefer the nearest server in the "east" data center also used for reporting,
// but fall back to a server in the "west" data center
$cursor->setReadPreference(MongoClient::RP_NEAREST, [
[ 'dc' => 'east', 'use' => 'reporting' ],
[ 'dc' => 'west' ],
] );
foreach ($cursor as $person) {
// ...
}
// If the read preference is changed, it will be used the next time the cursor
// is rewound and the command is re-executed.
$cursor->setReadPreference(MongoClient::RP_PRIMARY);
foreach ($cursor as $person) {
// ...
}
?>
官方地址:https://www.php.net/manual/en/mongocommandcursor.setreadpreference.php