The basics of aggregations

In contrast to search, analytics deals with the bigger picture. Searching addresses the need for zooming in to a few records; analytics addresses the need for zooming out and slicing the data in different ways. While learning about searching, we used the API of the following form:

POST /<index_name>/<type_name>/_search
{
  "query": 
  {
    ... type of query ...
  }
}

All aggregation queries take a common form. Let us understand the structure.

The aggregations or aggs element allows us to aggregate data. All aggregation requests take the following form:

POST /<index_name>/<type_name>/_search
{  
  "aggs": {                                 
    ... type of aggregation ...
          },
  "query": {  ... type of query ... },              //optional query part
  "size": 0                                         //size typically set to 0
}

The aggs element should contain the actual aggregation query. The body depends on the type of aggregation that...