1. A method of operating a distributed database comprising a plurality of database nodes each storing a plurality of data objects, the method comprising: when executing a database transaction that requires data operations be performed on a plurality of data objects that are distributed between at least two of the database nodes, grouping the data objects that are involved in the database transaction at one of the plurality of database nodes; and the grouping of the data objects at one of the plurality of database nodes comprises storing the data objects that are involved in the database transaction at the one of the plurality of database nodes as a data object group.