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5.6 Aggregation

Finally, let us show how the Faceted Query Engine handles queries that involve aggregation. As an example, suppose we wish to find the combined weight of all pottery.gifPottery per layer.gifLayer. We start by aggregating the entity set pottery.gifPottery by weight.

agg1.gif
Figure 21. Aggregation: choosing entity set

agg2.gif
Figure 22. Aggregation: choosing attribute

agg3.gif
Figure 23. Aggregation: inspecting attribute values

We then proceed to relate the new aggregate entity set to the entity set layer.gifLayers, in a manner similarly to section 5.4.

agg4.gif
Figure 24. Aggregation: choosing a related entity set

agg5.gif
Figure 25. Aggregation: relating entity sets (step 1)

agg6.gif
Figure 26. Aggregation: relating entity sets (step 2)

We save the new entity set, layer.gifLayers with Pottery, and start aggregation.

agg7.gif
Figure 27. Aggregation: inspecting intermediate results

agg8.gif
Figure 28. Aggregation: choosing aggregate function

agg9.gif
Figure 29. Aggregation: inspecting and saving query results

There are 6 layer.gifLayers with Pottery, and the combined weight of pottery per layer are displayed in the Detail window.


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