mondrian.olap

Interface Aggregator

All Known Implementing Classes:

RolapAggregator, RolapAggregator.AvgFromAvg, RolapAggregator.AvgFromSum, RolapAggregator.BaseAggor, RolapAggregator.SumFromAvg

public interface Aggregator

Describes an aggregation operator, such as "sum" or "count".

Since:

Jul 9, 2003$

Author:

jhyde$

See Also:

FunDef, Evaluator

Method Summary

Modifier and Type	Method and Description
Object	aggregate(Evaluator evaluator, TupleList members, Calc calc) Applies this aggregator to an expression over a set of members and returns the result.
Object	aggregate(List<Object> rawData, Dialect.Datatype datatype) Applies this aggregator over a raw list of objects for a rollup operation.
Aggregator	getRollup() Returns the aggregator used to combine sub-totals into a grand-total.
boolean	supportsFastAggregates(Dialect.Datatype datatype) Tells Mondrian if this aggregator can perform fast aggregation using only the raw data of a given object type.

Method Detail

getRollup

Aggregator getRollup()

Returns the aggregator used to combine sub-totals into a grand-total.

Returns:

aggregator used to combine sub-totals into a grand-total

aggregate

Object aggregate(Evaluator evaluator,
                 TupleList members,
                 Calc calc)

Applies this aggregator to an expression over a set of members and returns the result.

Parameters:

evaluator - Evaluation context

members - List of members, not null

calc - Expression to evaluate

Returns:

result of applying this aggregator to a set of members/tuples

supportsFastAggregates

boolean supportsFastAggregates(Dialect.Datatype datatype)

Tells Mondrian if this aggregator can perform fast aggregation using only the raw data of a given object type. This will determine if Mondrian will attempt to perform in-memory rollups on raw segment data by invoking aggregate(mondrian.olap.Evaluator, mondrian.calc.TupleList, mondrian.calc.Calc).

This is only invoked for rollup operations.

Parameters:

datatype - The datatype of the object we would like to rollup.

Returns:

Whether this aggregator supports fast aggregation

aggregate

Object aggregate(List<Object> rawData,
                 Dialect.Datatype datatype)

Applies this aggregator over a raw list of objects for a rollup operation. This is useful when the values are already resolved and we are dealing with a raw SegmentBody object.

Only gets called if supportsFastAggregates(mondrian.spi.Dialect.Datatype) is true.

This is only invoked for rollup operations.

Parameters:

rawData - An array of values in its raw form, to be aggregated.

Returns:

A rolled up value of the raw data. if the object type is not supported.