Abstract: Cache optimization for missing data is provided. A database system receives a first request for a database record. The database system determines whether the database record is stored in a cache. The database system determines whether the database record is stored in a data store in response to a determination that the database record is not stored in the cache. The database system stores a dummy entry for the database record in the cache in response to a determination that the database record is not stored in the data store. The database system receives a second request for the database record. The database system determines whether the database record is stored in the cache. The database system outputs an indication that the database record is unavailable in response to a determination that the dummy entry stored for the database record is in the cache.

Abstract: Contact recommendations based on purchase history are described. A system creates a directed graph of nodes in which at least some of the nodes are connected by directed arcs, wherein a directed arc from a first node to a second node represents a conditional probability that previous users who purchased a first contact also purchased a second contact. The system identifies a set of contacts purchased by a current user. The system estimates a prospective purchase probability based on a historical probability that previous users purchased a specific contact and a related probability that previous users who purchased the specific contact also purchased a contact in the set of contacts, for each candidate contact. The system outputs a recommendation for the current user to purchase a recommended candidate contact based on a corresponding prospective purchase probability.

Abstract: Cache optimization for missing data is provided. A database system receives a first request for a database record. The database system determines whether the database record is stored in a cache. The database system determines whether the database record is stored in a data store in response to a determination that the database record is not stored in the cache. The database system stores a dummy entry for the database record in the cache in response to a determination that the database record is not stored in the data store. The database system receives a second request for the database record. The database system determines whether the database record is stored in the cache. The database system outputs an indication that the database record is unavailable in response to a determination that the dummy entry stored for the database record is in the cache.

Abstract: Contact recommendations based on purchase history are described. A system creates a directed graph of nodes in which at least some of the nodes are connected by directed arcs, wherein a directed arc from a first node to a second node represents a conditional probability that previous users who purchased a first contact also purchased a second contact. The system identifies a set of contacts purchased by a current user. The system estimates a prospective purchase probability based on a historical probability that previous users purchased a specific contact and a related probability that previous users who purchased the specific contact also purchased a contact in the set of contacts, for each candidate contact. The system outputs a recommendation for the current user to purchase a recommended candidate contact based on a corresponding prospective purchase probability.

Abstract: A method of managing crowdsourced data includes storing contact information regarding a plurality of contacts within a community-updateable repository accessible by a plurality of users, receiving a plurality of discrepancy reports associated with a selected contact of the plurality of contacts, extracting fact data regarding the selected contact from the plurality of discrepancy reports, determining an action to be taken based on the fact data and a fact model applied to the fact data, and performing the action to modify the community-updateable repository.