Frequently Asked Questions

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Frequently Asked Questions

Q: Where does the Data Deriver Agent add new derived data in the database?


A: New derived data is added to the DT_LOGGER_DATUM table using the DT_LOGGER_SERIES.LOGGER_SERIES_ID created here (Step 1). The derived series data is just like any other data; it can be used in charts, alerts, other agents, etc.


The Data Deriver Agent can also be used to add derived data to other tables (e.g., DT_WATER_LEVEL, DT_RESULT, etc.). Please see the exportSqlProcedure page for more information.



Q: When does the Data Deriver Agent derive data—during source series data import or when a report is run?


A: The Data Deriver Agent is an EIA; it is run based on a schedule. The derived data is calculated (and added to the database) when the agent runs. To run the Data Deriver Agent, you need to create an EIA (using the EZView Widget) that runs at the desired frequency.



Q: If a SERIES_FUNCTION_INFO is changed, will the agent update existing records according to this new change?


A: Changes to the SERIES_FUNCTION_INFO will affect future derived data, but not past data. For example, suppose you setup a SERIES_FUNCTION_INFO to calculate the daily average on an input series. Six months later, suppose that you change the SERIES_FUNCTION_INFO to calculate the daily maximum. Just changing the SERIES_FUNCTION_INFO value parameter from average to maximum will not automatically change the daily averages that were computed for the first six months. However, future derived values (after the change is made) will be maximums, not averages. If you delete the first six months of averages from the DT_LOGGER_DATUM table, then it will recompute ALL of the values based on the new formula (i.e., the maximums).


Changes to historical Data Deriver Agent data can also be performed by using the Data Deriver Update Agent.



Q: What calculations may be used in SERIES_FUNCTION_INFO as a value parameter?


A: For easy calculations, please see some of the examples in Step-by-step example or SERIES_FUNCTION_INFO. For more complex calculations, please see customFunction.