Bucket aggregations

Bucket aggregations create buckets of documents. Each bucket has a criterion that determines which types of document fall into it. As opposed to metrics, they can hold sub-aggregations, known as child buckets, within a parent bucket. Let's cover some of the bucket aggregation types.

Adjacency matrix aggregation

This bucket aggregation returns a form of adjacency matrix. Each bucket represents a cell in the matrix of intersecting filters. For example, given three filters, A, B and C, the response will return the following:

	A	B	C
A	A	A&B	A&C
B		B	B&C
C			C

The buckets B&A, C&A, and C&B are not included as they are already in the table (as...