1. A computer-implemented method to merge topics associated with a content item of an online application, the method comprising: receiving a request to merge a first topic with a second topic of a plurality of topics, the plurality of topics stored as separate records in a database table, each record having a first field to store a topic identifier that identifies its respective topic and a second field to store a topic identifier into which the respective topic has been merged, and a third field to store a topic name different than the topic identifier; responsive to reading the second field of the record for the second topic to determine that the second topic has not been merged with another topic, using processor-implemented topic merge logic to write the topic identifier of the second topic into the second field of the record for the first topic to indicate that the first topic has been merged into the second topic; identify ones of the plurality of topics that have been merged into the first topic; for each of the first topic and the ones of the plurality of topics that have been merged into the first topic, identify at least one of a question and a user associated with the first topic and the ones of the plurality of topics; for each of the question and the user, merge the questions and the users on an associated question table and user table, respectively; and provide a list of questions and users associated with the first topic to an application logic component.