mongodb replicates and error err not master and slaveOk false code 13435

Question

I tried mongo replica sets for the first time   I am using ubuntu on ec2 and I booted up three instances  I used the private IP address of each of the instances   I picked on as the primary and below is the code   mongo --host Private IP Address rs initiate   rs add    Private IP Address     rs addArb    Private IP Address       All at this point is fine   When I go to the http   ec2-xxx-xxx-xxx-xxx compute-1 amazonaws com 28017  replSet site I see that I have a primary  seconday  and arbitor   Ok  now for a test     On the primary create a database in this is the code   use tt db tt save    a   123       on the secondary  I then do this and get the below error   db tt find   error      err     not master and slaveOk false    code    13435     I am very new to mongodb and replicates but I thought that if I do something in one  it goes to the other   So  if I add a record in one  what do I have to do to replicate across machines

User · Answer

You have to set  quot secondary okay quot  mode to let the mongo shell know that you re allowing reads from a secondary  This is to protect you and your applications from performing eventually consistent reads by accident  You can do this in the shell with  rs secondaryOk    After that you can query normally from secondaries  A note about  quot eventual consistency quot   under normal circumstances  replica set secondaries have all the same data as primaries within a second or less  Under very high load  data that you ve written to the primary may take a while to replicate to the secondaries  This is known as  quot replica lag quot   and reading from a lagging secondary is known as an  quot eventually consistent quot  read  because  while the newly written data will show up at some point  barring network failures  etc   it may not be immediately available  Edit  You only need to set secondaryOk when querying from secondaries  and only once per session

User · Answer

To avoid typing rs slaveOk   every time  do this   Create a file named replStart js  containing one line  rs slaveOk    Then include --shell replStart js when you launch the Mongo shell   Of course  if you re connecting locally to a single instance  this doesn t save any typing

User · Answer

WARNING  slaveOk   is deprecated and may be removed in the next major release  Please use secondaryOk   instead   rs secondaryOk

User · Answer

in mongodb2 0  you should type  rs slaveOk     in secondary mongod node

User · Answer

slaveOk does not work anymore  One needs to use readPreference https   docs mongodb com v3 0 reference read-preference  primaryPreferred  e g    const client   new MongoClient mongoURL     readPreference primaryPreferred     useUnifiedTopology  true  useNewUrlParser  true

User · Answer

I got here searching for the same error  but from Node js native driver  The answer for me was combination of answers by campeterson and Prabhat    The issue is that readPreference setting defaults to primary  which then somehow leads to the confusing slaveOk error  My problem is that I just wan to read from my replica set from any node  I don t even connect to it as to replicaset  I just connect to any node to read from it    Setting readPreference to primaryPreferred  or better to the ReadPreference PRIMARY PREFERRED constant  solved it for me  Just pass it as an option to MongoClient connect   or to client db   or to any find    aggregate   or other function     https   docs mongodb com v3 0 reference read-preference  primaryPreferred http   mongodb github io node-mongodb-native 3 6 api Collection html  search readPreference    const   MongoClient  ReadPreference     require  mongodb    const client   await MongoClient connect MONGODB CONNECTIONSTRING    readPreference  ReadPreference PRIMARY PREFERRED

User · Answer

I am just adding this answer for an awkward situation from DB provider   what happened in our case is the primary and secondary db shifted reversely  primary to secondary and vice versa  and we are getting the same error   so please check in the configuration settings for database status which may help you

User · Answer

THIS IS JUST A NOTE FOR ANYONE DEALING WITH THIS PROBLEM USING THE RUBY DRIVER  I had this same problem when using the Ruby Gem   To set slaveOk in Ruby  you just pass it as an argument when you create the client like this   mongo client   MongoClient new  localhost   27017    slave ok  true      https   github com mongodb mongo-ruby-driver wiki Tutorial making-a-connection  mongo client   MongoClient new    optional host port args    Notice that  args  is the third optional argument

[mongodb] mongodb, replicates and error: { "$err" : "not master and slaveOk=false", "code" : 13435 }

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