1. A database management system, comprising: a first data storage structure configured to store one or more datasets for each of a plurality of devices, each dataset comprising unordered timestamped data elements that indicate statuses of a particular device related condition at different points in time; a second data storage structure configured to store and map between: device identifiers that identify the devices, condition identifiers that identify the device related conditions, and timestamps that identify when two temporally consecutive data elements of a given dataset indicate different statuses, wherein the data storage management system is operable to update the second data storage structure whenever a new data element of one of the datasets indicating a status different from the status indicated by a temporally preceding data element of said one of the datasets is stored in the first data storage structure; and a data access unit configured to, in response to receiving a request for data in respect of a specified time period and at least one device related condition of at least one device, use the second data storage structure to identify when one or more status changes occurred within the specified time period for said at least one device related condition.