Change Streams not working

[philkunz]

Any reason why the replica set created with mongodb-memory-server does not work for change streams in general?
while Atlas just works?

const changeStream = mongoDbCollection.watch([], {
    fullDocument: 'updateLookup'
});

[nodkz]

Please read requirements for streams in mongodb and use proper engine and other settings when you spin up your replica set
https://www.mongodb.com/docs/manual/changeStreams/#availability

If you get working solution, please share it here.
Tnx.

[philkunz]

I confirm. Simply switching to wiredTiger as storage engine works.

[sibelius]

do you have a test example of change stream working ?

[noghartt]

See below an example to replace the storageEngine for wiredTiger:

  await MongoMemoryReplSet.create({
    instanceOpts: [{ storageEngine: 'wiredTiger' }, { storageEngine: 'wiredTiger' }],
    binary: {
      systemBinary: process.env.MONGODB_BINARY,
      skipMD5: true,
    },
    replSet: {
      count: 2,
    },
  });

You can put the storageEngine inside replSet too:

  await MongoMemoryReplSet.create({
    binary: {
      systemBinary: process.env.MONGODB_BINARY,
      skipMD5: true,
    },
    replSet: {
      count: 2,
      storageEngine: 'wiredTiger',
    },
  });

[diegosasw]

So, is it possible to have a single docker image with mongodb-memory-server spinning up a replica set so that the change streams work?

I created a docker image (See this https://gitlab.com/sunnyatticsoftware/sandbox/mongo-rs and https://stackoverflow.com/q/76335421/2948212) that contains a replica set (3 nodes) but I'd like it to be in-memory persistence, and I found this project.

I didn't understand if this is currently supported?

[hasezoey]

So, is it possible to have a single docker image with mongodb-memory-server spinning up a replica set so that the change streams work?

yes, you just need to explicitly set the storage engine used, because the default (in mongodb versions before 7.0) is set to ephermeralForTest in mongodb-memory-server, which does not support change streams