| 摘要 |
Each of a plurality of data items has an associated update time. Identifying updated data items comprises identifying those data items that have an update time later than a last synchronization time. The data items are updated such that each data item is associated with one of a plurality of update tokens. Each update token is associated with updates performed up to a respective bound period from a time at which the update token is superseded by a successive update token. The update tokens are allocated successively in a monotonic sequence. Data indicating a last synchronization time is received. An update token is identified that is associated with one or more updates performed relative to a point in time related to the last synchronization time by the bound period. Data items having an update time after the last synchronization time are identified on the basis of the identified update token. |
