Definição
cursor.noCursorTimeout()Importante
Método mongosh
This page documents a
mongoshmethod. This is not the documentation for a language-specific driver, such as Node.js.Para drivers de API do MongoDB, consulte a documentação do driver do MongoDB específica da linguagem.
Instrui o servidor para evitar fechar um cursor automaticamente após um período de inatividade.
The
noCursorTimeout()method has the following prototype form:db.collection.find(<query>).noCursorTimeout()
Compatibilidade
Esse método está disponível em implantações hospedadas nos seguintes ambientes:
- MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud
Importante
This command is not supported in M0 and Flex clusters. For more information, see Unsupported Commands.
MongoDB Enterprise: a versão autogerenciada e baseada em assinatura do MongoDB
MongoDB Community: uma versão com código disponível, de uso gratuito e autogerenciada do MongoDB
Comportamento
Substituições de tempo limite de inatividade da sessão 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.
Atualizar um cursor com refreshSessions
Para operações que retornam um cursor, se o cursor ficar inativo por mais de 30 minutos, execute a operação em uma sessão explícita usando e atualize periodicamente Mongo.startSession() refreshSessions a sessão usando o comando. Por exemplo:
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.