Mongo客户端不从辅助服务器读取

Question

我正在尝试在AWS上使用documentDB集群。在这个集群上，我有2个实例，一个主实例用于写操作，另一个从实例用于读操作…

如果我像这样用connectionString创建连接:

String host = getHost();
Integer port = Integer.parseInt(getPort());
String[] arrCredentials = getCredentials();
String credentials = String.format("%s:%s", arrCredentials[0], arrCredentials[1]);
String database = getDatabase();
String options = "ssl=true&replicaSet=rs0&readPreference=secondaryPreferred";

String connection = String.format("mongodb://%s@%s:%d/%s?%s", 
credentials, host, port, database, options);
return MongoClients.create(new ConnectionString(connection));

它工作得很好，readOps由辅助实例提供…

但是，当我尝试这样使用MongoClients.create()时:

public MongoClient mongoClient() {
return MongoClients.create(MongoClientSettings.builder()
.applyToClusterSettings(settings ->
settings
.hosts(singletonList(new ServerAddress(
getHost(), Integer.parseInt(getPort()))))
.requiredReplicaSetName("rs0")
.requiredClusterType(ClusterType.REPLICA_SET)
)
.applyToSslSettings(setting ->
setting.enabled(true)
)
.readPreference(ReadPreference.secondaryPreferred())
.credential(getCredential())
.build());
}

所有的调用，readOps和writeOps，都由主实例提供。

Answer 1

我找到了!

与ConnectionString一起创建MongoClienteSettings时，"ClusterMode"的值自动设置为"MULTIPLE"。这不会发生在Builder…

因此，要获得与MongoClientSetting.Builder()相同的行为，您需要设置它。这样的:

public MongoClient mongoClient() {
return MongoClients.create(MongoClientSettings.builder()
.applyToClusterSettings(settings ->
settings
.hosts(singletonList(new ServerAddress(
getHost(), Integer.parseInt(getPort()))))
.requiredReplicaSetName("rs0")
.requiredClusterType(ClusterType.REPLICA_SET)
.mode(ClusterConnectionMode.MULTIPLE))
)
.applyToSslSettings(setting ->
setting.enabled(true)
)
.readPreference(ReadPreference.secondaryPreferred())
.credential(getCredential())
.build());
}

现在运行正常了:)

AWS CloudWatch指标