| 摘要 |
A method of accessing data in a database management system includes in a first storage structure, storing one or more datasets for each of plural devices, each dataset comprising unordered timestamped data elements indicating statuses of a particular device related condition at different points in time, in a second storage structure, storing and mapping between: device identifiers identifying the devices, condition identifiers identifying the device related conditions, and timestamps identifying when two temporally consecutive data elements of a given dataset indicate different statuses, receiving a new data element indicating a status of one particular device related conditions, storing the new data element in the first storage structure, determining whether or not the status indicated by the new data element is different from the status indicated by a temporally preceding data element stored in first storage structure, and updating the timestamps if the determination is positive.
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