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One of the most important concepts of Delft-FEWS is that always the latest forecast data is available to be used. In a typical operational Delft-FEWS forecasting system, new data is constantly imported, while older data is no longer relevant and can be removed. For a lot of database tables in the central Delft-FEWS database, the rows (records) in the database have an expiryTime column specifying when the data can be removed. This expiryTime is set at creationTime. The removal is done by a continous running process in the Master Controller called the McRollingBarrel. The McRollingBarrel - in 10 minute intervals - removes data for which the expiry time is exceeded and no dependent rows are available. This is often critical for maintaining an optimal application performance.

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Delft-FEWS allows for fine grained control of expiry times for timeseries by specifying the default in a global propery and overriding the expiry time on a deeper level for instance in the configuration of the import. Once configured, it is good practive to verify the expiry times of imported data using Time Series Lister.

  1. The System default expiry time for forecast data in Delft-FEWS is 10 days. The system default can be altered by specifying a global property, e.g. DEFAULT_EXPIRY_DAYS=30

    Code Block
    languagexml
    DEFAULT_EXPIRY_DAYS=30


  2. Import workflows can have expiry time in general section, will be used for all imported time series

    Code Block
    languagexml
    <expiryTime unit="day" multiplier="365"/>


  3. Import, Transformation, General Adapter, .. modules can have expiry times in timeSeriesSet element, e.g.

    Code Block
    languagexml
    <expiryTime unit="day" multiplier="2"/>



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