Group statistics - aggregate clause

Syntax of an aggregate clause:

group_key:field, range:number1~number2, agg_fun:func1#func2, max_group:number2, 
agg_filter:filter_clause, max_group:number

Parameters:

• An aggregate clause is optional.

• The fields that are referenced in the preceding parameters must be configured as attribute fields when you define the application schema.

• The result of an aggregate clause is returned to the facet node, which is a node that is used for searches. The functions, such as sum() and count(), that are specified by the agg_fun parameter display the statistics.

• You can specify multiple group_key parameters in an aggregate clause to collect statistics for different fields at the same time. Separate calculations for the fields with semicolons (;).

Example:

group_key:field1,agg_fun:func1;group_key:field2,agg_fun:func2

• The result of the aggregate clause is returned to the facet node. To display statistics in the return result, you must set the format of the config clause to full JSON.

• The distinct_count feature is supported only in an exclusive cluster. To use this feature, you must add the enable_accurate_statistics parameter into a kvpairs clause and set this parameter to true. When this feature is used, the system returns only the statistics in the facet node for a query.

• The count(), max(), min(), and sum() functions are supported in an exclusive cluster. To use these functions, you must add the enable_accurate_statistics parameter into a kvpairs clause and set this parameter to true.

• The system can return accurate statistics of up to 100,000 documents. If the number of documents that match the specified conditions exceeds 100,000, the statistics that are returned may be inaccurate due to the limits on engine performance. For an exclusive cluster, you can add the enable_accurate_statistics parameter into a kvpairs clause and set this parameter to true. This way, the system can return more accurate statistics.

1. Use the following query clause to obtain the statistics of documents that contain "Zhejiang University". Statistics are calculated based on the group_id and company_id fields. For the group_id fields, the statistics include the value sum and maximum value of the price field. For the company_id field, the statistics include the number of times each company occurs.

   query=default:'Zhejiang University'&&aggregate=group_key:group_id,agg_fun:sum(price)#max(price);group_key:company_id,agg_fun:count()

   Sample return result:

   {
   　　status: "OK",
   　　result: {
   　　　　searchtime: 0.015634,
   　　　　total: 5,
   　　　　num: 1,
   　　　　viewtotal: 5,
   　　　　items: [        // The return result.
   　　　　　　{ ... }
   　　　　],
   　　　　facet: [
   　　　　　　{
   　　　　　　　　key: "group_id",
   　　　　　　　　items: [
   　　　　　　　　　　{
   　　　　　　　　　　　　value: 43,
   　　　　　　　　　　　　sum: 81,
   　　　　　　　　　　　　max: 20,
   　　　　　　　　　　},
   　　　　　　　　　　{
   　　　　　　　　　　　　value: 63,
   　　　　　　　　　　　　sum: 91,
   　　　　　　　　　　　　max: 50,
   　　　　　　　　　　},
   　　　　　　　　],
   　　　　　　},
   　　　　　　{
   　　　　　　　　key: "company_id",
   　　　　　　　　items: [
   　　　　　　　　　　{
   　　　　　　　　　　　　value: 13,
   　　　　　　　　　　　　count: 4,
   　　　　　　　　　　},
   　　　　　　　　　　{
   　　　　　　　　　　　　value: 10,
   　　　　　　　　　　　　count: 1,
   　　　　　　　　　　},
   　　　　　　　　],
   　　　　　　},
   　　　　],
   　　},
   　　errors: [ ],
   　　tracer: "",
   },

2. Use the following query clause to obtain the statistics of documents that contain "Zhejiang University" based on the group_id field. The value sum of the price field is calculated. Documents whose ranks are lower than 10,000 are sampled. The sampling step size is set to 5.

   query=default:'Zhejiang University'&&aggregate=group_key:group_id,agg_fun:sum(price), agg_sampler_threshold:10000, agg_sampler_step:5

3. Use the following query clause to obtain the statistics of documents that contain "Zhejiang University" based on the group_id field. The aggregate clause counts the number of documents whose values of the group_id field are in the range from 10 to 50.

   query=default:'Zhejiang University'&&aggregate=group_key:group_id,agg_fun:count(),range:10~50

4. Use the following query clause to obtain the statistics of documents that contain "Zhejiang University" based on the group_id field. The maximum value sum of the hits and replies fields is calculated among documents whose values of the create_timestamp field are greater than 1423456781.

   query=default:'Zhejiang University'&&aggregate=group_key:group_id,agg_fun:max(hits+replies),agg_filter:create_timestamp>1423456781