1. An apparatus comprising: one or more processors; and a computer readable storage medium having computer readable program code embodied therewith and executable by the one or more processors, the computer readable program code comprising: computer readable program code configured to send one or more queries to a data warehouse; computer readable program code configured to evaluate a trigger condition; computer readable program code configured to, responsive to a determination that the trigger condition is not satisfied by a query result obtained from the one or more queries sent to the data warehouse, send one or more differential queries to one or more remote data sources; and computer readable program code configured to determine an aggregate query result, the aggregate query result comprising an aggregation of the query result obtained from the one or more queries sent to the data warehouse and one or more query results obtained from the one or more differential queries.