Fetching Data In NetFlow Charting Widgets

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NetFlow charting widget fetches source data using a query of the following form:

SELECT

 <keyExpression> AS key

 <valueExpression> AS value

FROM <dataSource> AS data

GROUP BY <groupExpression>

ORDER BY <orderExpression> DESC

LIMIT <limitExpression>

The concrete text of the query is determined by NetFlow view and filter parameters. The query is actually performed in two steps:

1.Raw data is effectively fetched and filtered using getNetFlowData function. The filter parameters are specified at run time via corresponding GUI components in the Filter panel of the widget (see below).
2.The raw data is processed with the query according to the specified query clauses. The keyExpression, valueExpression, groupExpression, orderExpression and limitExpression clauses are specified by the view the widget was built from.

The query returns a table with key and value columns. This table is used to build the widget's chart. This data in numerical form can be viewed with a Data Table Editor in the Data panel of the widget (see below).