code: function _fullyReady(callback) {
      var self = this;
  
      var promise = self._initReady().then(function () {
          var dbContext = dbContexts[self._dbInfo.name];
  
          if (dbContext && dbContext.dbReady) {
              return dbContext.dbReady;
          }
      });
  
      executeTwoCallbacks(promise, callback, callback);
      return promise;
  }
docs: Specialize the default `ready()` function by making it dependent on the current database operations. Thus, the driver will be actually ready when it's been initialized (default) *and* there are no pending operations on the database (initiated by some other instances).