The MongoDB\Driver\ReadPreference class

(mongodb >=1.0.0)

Introduction

final class MongoDB\Driver\ReadPreference implements MongoDB\BSON\Serializable, Serializable {

/* Properties */

public readonly string $mode;

public readonly ?array $tags;

public readonly int $maxStalenessSeconds;

public readonly ?object $hedge;

/* Constants */

const string PRIMARY = primary;

const string PRIMARY_PREFERRED = primaryPreferred;

const string SECONDARY = secondary;

const string SECONDARY_PREFERRED = secondaryPreferred;

const string NEAREST = nearest;

const int NO_MAX_STALENESS = -1;

const int SMALLEST_MAX_STALENESS_SECONDS = 90;

/* Methods */

final public function bsonSerialize(): stdClass

final public function __construct(string $mode, ?array $tagSets = null, ?array $options = null)

final public function getHedge(): ?object

final public function getMaxStalenessSeconds(): int

final public function getMode(): int

final public function getModeString(): string

final public function getTagSets(): array

}

mode: The read preference mode as a string (e.g. "primary", "secondary").
tags: The tag set list used by the read preference, or null if no tag sets were specified.
maxStalenessSeconds: The maximum staleness in seconds for reads, or MongoDB\Driver\ReadPreference::NO_MAX_STALENESS if no maximum staleness was specified.
hedge: A document specifying the hedge options for the read preference, or null if no hedge options were specified.

Warning
This property is deprecated as hedged reads are deprecated in MongoDB 8.0.

MongoDB\Driver\ReadPreference::PRIMARY: All operations read from the current replica set primary. This is the default read preference for MongoDB.
MongoDB\Driver\ReadPreference::PRIMARY_PREFERRED: In most situations, operations read from the primary but if it is unavailable, operations read from secondary members.
MongoDB\Driver\ReadPreference::SECONDARY: All operations read from the secondary members of the replica set.
MongoDB\Driver\ReadPreference::SECONDARY_PREFERRED: In most situations, operations read from secondary members but if no secondary members are available, operations read from the primary.
MongoDB\Driver\ReadPreference::NEAREST: Operations read from member of the replica set with the least network latency, irrespective of the member's type.
MongoDB\Driver\ReadPreference::NO_MAX_STALENESS: The default value for the "maxStalenessSeconds" option is to specify no limit on maximum staleness, which means that the driver will not consider a secondary's lag when choosing where to direct a read operation.
MongoDB\Driver\ReadPreference::SMALLEST_MAX_STALENESS_SECONDS: The minimum value for the "maxStalenessSeconds" option is 90 seconds. The driver estimates secondaries' staleness by periodically checking the latest write date of each replica set member. Since these checks are infrequent, the staleness estimate is coarse. Thus, the driver cannot enforce a max staleness value of less than 90 seconds.

Version	Description
PECL mongodb 2.3.0	Added public readonly properties.
PECL mongodb 2.0.0	Removed the `MongoDB\Driver\ReadPreference::RP_PRIMARY`, `MongoDB\Driver\ReadPreference::RP_PRIMARY_PREFERRED`, `MongoDB\Driver\ReadPreference::RP_SECONDARY`, `MongoDB\Driver\ReadPreference::RP_SECONDARY_PREFERRED`, and `MongoDB\Driver\ReadPreference::RP_NEAREST` constants. The getMode() method was also removed.
PECL mongodb 1.20.0	Deprecated the `MongoDB\Driver\ReadPreference::RP_PRIMARY`, `MongoDB\Driver\ReadPreference::RP_PRIMARY_PREFERRED`, `MongoDB\Driver\ReadPreference::RP_SECONDARY`, `MongoDB\Driver\ReadPreference::RP_SECONDARY_PREFERRED`, and `MongoDB\Driver\ReadPreference::RP_NEAREST` constants.
PECL mongodb 1.7.0	Added the `MongoDB\Driver\ReadPreference::PRIMARY`, `MongoDB\Driver\ReadPreference::PRIMARY_PREFERRED`, `MongoDB\Driver\ReadPreference::SECONDARY`, `MongoDB\Driver\ReadPreference::SECONDARY_PREFERRED`, and `MongoDB\Driver\ReadPreference::NEAREST` constants. Implements Serializable.
PECL mongodb 1.2.0	Added the `MongoDB\Driver\ReadPreference::NO_MAX_STALENESS` and `MongoDB\Driver\ReadPreference::SMALLEST_MAX_STALENESS_SECONDS` constants. Implements MongoDB\BSON\Serializable.

MongoDB\Driver\ReadPreference::bsonSerialize — Returns an object for BSON serialization
MongoDB\Driver\ReadPreference::__construct — Create a new ReadPreference
MongoDB\Driver\ReadPreference::getHedge — Returns the ReadPreference's "hedge" option
MongoDB\Driver\ReadPreference::getMaxStalenessSeconds — Returns the ReadPreference's "maxStalenessSeconds" option
MongoDB\Driver\ReadPreference::getMode — Returns the ReadPreference's "mode" option
MongoDB\Driver\ReadPreference::getModeString — Returns the ReadPreference's "mode" option
MongoDB\Driver\ReadPreference::getTagSets — Returns the ReadPreference's "tagSets" option