Read preference does not seem to be working

[ryanogle]

I was on an older version of mongoose and mongo driver (mongoose@3.6.4 & mongodb@1.2.14), and since upgrading to the newest version (mongoose@3.8.1 & mongodb@1.3.23) my read preference set on the collection level no longer seems to work. I also tried to set it on the query level, and it doesn't seem to work:

    User.find({
      my_field: {
        $in: my_ids
      }
    }, my_fields, function (err, results) {
      cb(err, results);
    }).read('secondary');

Everything seems to be going to the primary. Rolling back to the old versions shows the expected behavior - queries going to the secondary.

I also tried to follow exactly the mongoose api docs:

    var query = User.find({
      my_field: {
        $in: my_ids
      }
    }, my_fields ).read('secondary');

    query.exec(function (err, result) {
      cb(err, result);
    });

And same result, queries going to primary only. When I roll back to 3.6.4, reads start going to the secondaries (I'm setting the read preference on the collection).

[dpomerantz]

I have noticed the same thing. I believe it has to do with some of the createConnection() code that stores a flag as read_preference when it should be readPreference.

When I add the options to db under server options it works better.

e.g.

var options = {
// some other stuff
db : {
readPreference : "secondary"
}
};

To confirm the bug, I added a print statement in the code that searches for a machine to connect to. When only including in the url, the code uses a function called checkoutWriter() (part of mongo driver). When I add the setting above, it properly hits the checkoutReader() code.

[aheckmann]

Please retest using 3.8.7 and let us know.

[vkarpov15]

Stale issue, re-open if this is still a problem.