定義
cursor.noCursorTimeout()重要
mongosh メソッド
This page documents a
mongoshmethod. This is not the documentation for a language-specific driver, such as Node.js.MongoDB API ドライバーについては、各言語の「MongoDB ドライバーのドキュメント」を参照してください。
非アクティブな状態が一定期間続いた後、カーソルを自動的に閉じないようサーバーへ指示します。
The
noCursorTimeout()method has the following prototype form:db.collection.find(<query>).noCursorTimeout()
互換性
このメソッドは、次の環境でホストされている配置で使用できます。
- MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud
重要
This command is not supported in M0 and Flex clusters. For more information, see Unsupported Commands.
MongoDB Enterprise: サブスクリプションベースの自己管理型 MongoDB バージョン
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動作
セッション アイドル タイムアウトの上書き noCursorTimeout
MongoDB drivers and mongosh associate all operations with a server session, with the exception of unacknowledged write operations. For operations not explicitly associated with a session (i.e. using Mongo.startSession()), MongoDB drivers and mongosh create an implicit session and associate it with the operation.
If a session is idle for longer than 30 minutes, the MongoDB server marks that session as expired and may close it at any time. When the MongoDB server closes the session, it also kills any in-progress operations and open cursors associated with the session. This includes cursors configured with noCursorTimeout() or a maxTimeMS() greater than 30 minutes.
Consider an application that issues a db.collection.find() with cursor.noCursorTimeout(). The server returns a cursor along with a batch of documents defined by the cursor.batchSize() of the find(). The session refreshes each time the application requests a new batch of documents from the server. However, if the application takes longer than 30 minutes to process the current batch of documents, the session is marked as expired and closed. When the server closes the session, it also kills the cursor despite the cursor being configured with noCursorTimeout(). When the application requests the next batch of documents, the server returns an error.
カーソルの更新 refreshSessions
カーソルを返す操作の場合、カーソルが 30 分以上アイドル状態になる可能性がある場合は、 Mongo.startSession()を使用して明示的なセッション内で操作を発行し、 refreshSessionsコマンドを使用して定期的にセッションを更新します。以下がその例です。
var session = db.getMongo().startSession() var sessionId = session sessionId // show the sessionId var cursor = session.getDatabase("examples").getCollection("data").find().noCursorTimeout() var refreshTimestamp = new Date() // take note of time at operation start while (cursor.hasNext()) { // Check if more than 5 minutes have passed since the last refresh if ( (new Date()-refreshTimestamp)/1000 > 300 ) { print("refreshing session") db.adminCommand({"refreshSessions" : [sessionId]}) refreshTimestamp = new Date() } // process cursor normally }
In the example operation, the db.collection.find() method is associated with an explicit session. The cursor is configured with cursor.noCursorTimeout() to prevent the server from closing the cursor if idle. The while loop includes a block that uses refreshSessions to refresh the session every 5 minutes. Since the session will never exceed the 30 minute idle timeout, the cursor can remain open indefinitely.
For MongoDB drivers, defer to the driver documentation for instructions and syntax for creating sessions.