1. A method comprising maintaining a database persistently on a physical storage medium, partitioning the database into regions based on characteristics of items of data in the database, receiving tasks that are in contention to write data to the respective regions, reducing the contention among the received tasks by creating jobs that are based on each of the tasks, each of the jobs needing to write data in no more than one of the regions, for each of the regions, queuing only those jobs that need to write data in the region and executing the queued jobs for each region, one job after another and without contention, and executing jobs that are queued for different regions simultaneously, in parallel, and without contention.