Add a group by visitor (backport 14.x)

Description

The current aggregation visitors (AverageVisitor, CountVisitor, MaxVisitor, MedianVisitor, MinVisitor, StandardDeviationVisitor and SumVisitor) don’t support a “group by” behavior. For example, we are able to compute the average electrical consumption per building. But we are not able to ask the average electrical consumption per building type.

The idea is to add new "group by" visitor that will be able to group features by type and apply a visitor on them. The JDBCDataStore will be extend to natively support the "group by" behavior. The existing Aggregator process will also be extended to support the "group by" behavior.

All of this will be done preserving backwards compatibility.

Mailing list discussion about this:
http://osgeo-org.1560.x6.nabble.com/Adding-quot-group-by-quot-support-to-the-current-aggregation-visitors-td5249393.html

Environment

None

Assignee

Nuno Oliveira

Reporter

Nuno Oliveira

Triage

None

Components

Fix versions

Priority

Medium
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