Abstract: A facility is described that receives from a first user data specifying a question, a geographic location, and a time period. The facility receives an answer to the specified question from a second user at a time. The facility determines a geographic location of the second user at the time. The facility presents the received answer to the first user only if the time is during the time period and the determined geographic location is within a threshold distance of the specified geographic location.

Abstract: Systems, methods, and computer program products of distributing sorted sets to multiple nodes of a distributed in-memory database system are described. The distributed in-memory database system is a database system based on key-value pairs. The system receives data records including user data and scores for sorting. The system maps the user data to keys in the key-value pairs. The system maps the scores to the values in the key-value pairs. The system then distributes the mapped key-value pairs to the nodes. The distributed in-memory database system is indexed on the values.