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Base expression node that represents an aggregation function such as 'sum' or 'count'. In terms of validation each concrete aggregation node must implement it's own validation. In terms of evaluation this base class will ask the assigned net.esper.eql.core.AggregationResultFuture for the current state, using a column number assigned to the node. Concrete subclasses must supply an aggregation state prototype node net.esper.eql.core.Aggregator that reflects each group's (there may be group-by critera) current aggregation state.

The following tables list the members exposed by the ExprAggregateNode type.

Public Properties

  NameDescription
AggregationFunction
Returns the aggregation state prototype for use in grouping aggregation states per group-by keys.

ChildNodes
Returns list of child nodes.
(Inherited from ExprNode.)
ExpressionString
Renders the aggregation function expression.
(Overrides .ExpressionString.)
IsDistinct
Returns true if the aggregation node is only aggregatig distinct values, or false if aggregating all values.

PrototypeAggregator
Returns the aggregation state prototype for use in grouping aggregation states per group-by keys.

ReturnType
Returns the type that the node's evaluate method returns an instance of.
(Inherited from ExprNode.)

Protected Properties

  NameDescription
AggregationFunctionName
Returns the aggregation function name for representation in a generate expression string.