MongoDB\Driver\ReadConcern::__construct
(mongodb >=1.0.0)
MongoDB\Driver\ReadConcern::__construct — Construct immutable ReadConcern
説明
final public MongoDB\Driver\ReadConcern::__construct
([ string
$level
] )Creates a new ReadConcern.
パラメータ
-
level -
Read concern Value Description MongoDB\Driver\ReadConcern::LINEARIZABLEA linearizable read avoids returning reads from a stale primary (one that has already been superseded by a new primary but doesn't know it yet). It is important to note that this read concern level does not by itself produce linearizable reads; they must be issued in conjunction with MongoDB\Driver\WriteConcern::MAJORITYwrites to the same document(s) in order to be linearizable.MongoDB\Driver\ReadConcern::LOCALQueries using this read concern will return the node's most recent copy of the data. This provides no guarantee that the data has been written to a majority of the nodes (i.e. it may be rolled back). This is the default read concern for MongoDB. MongoDB\Driver\ReadConcern::MAJORITYQueries using this read concern will return the node's most recent copy of the data confirmed as having been written to a majority of the nodes (i.e. the data cannot be rolled back).
エラー / 例外
- 引数のパースに失敗した場合に MongoDB\Driver\Exception\InvalidArgumentException をスローします。
例
例1 MongoDB\Driver\ReadConcern::__construct() example
<?php
/* Unspecified read isolation level (uses the server's default behavior) */
$rc = new MongoDB\Driver\ReadConcern();
/* Request read isolation from a single replica set node */
$rc = new MongoDB\Driver\ReadConcern(MongoDB\Driver\ReadConcern::LOCAL);
/* Request read isolation from a majority of the replica set nodes */
$rc = new MongoDB\Driver\ReadConcern(MongoDB\Driver\ReadConcern::MAJORITY);
?>
忘却曲線を使ってこの知識を確実に記憶に残す
