| 摘要 |
A database server for handling steams of time stamped data points for tagged variables is disclosed herein that supports a set of advanced data retrieval operations/queries invoked by clients of the database server. The advanced data retrieval operations are invoked by client queries to provide, on demand, secondary information by processing previously tabled data corresponding to received data streams rendered by a variety of data sources in a supervisory control/monitoring, process control and/or automated equipment environment. Calculations, on previously stored data, for rendering the secondary information are performed within the database server at the time the secondary information is requested by a client of the historian that maintains a database containing the previously stored data.
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