group (Aggregate Function)
This function aggregates the JSON elements and returns a JSON object by adding enclosing.element if it is provided. If enclosing.element is not provided, then it aggregate the JSON elements returns a JSON array.
Syntax
<OBJECT> json:group(<STRING|OBJECT> json)
<OBJECT> json:group(<STRING|OBJECT> json, <BOOL> distinct)
<OBJECT> json:group(<STRING|OBJECT> json, <STRING> enclosing.element)
<OBJECT> json:group(<STRING|OBJECT> json, <STRING> enclosing.element, <BOOL> distinct)
Query Parameters
| Name | Description | Default Value | Possible Data Types | Optional | Dynamic |
|---|---|---|---|---|---|
| json | The JSON element that needs to be aggregated. | STRING OBJECT | No | Yes | |
| enclosing.element | The JSON element used to enclose the aggregated JSON elements. | EMPTY_STRING | STRING | Yes | Yes |
| distinct | This is used to only have distinct JSON elements in the concatenated JSON object/array that is returned. | false | BOOL | Yes | Yes |
Example 1
@info(name = 'query1')
SELECT json:group("json") AS groupedJSONArray
FROM InputStream WINDOW SLIDING_LENGTH(5)
INPUT OutputStream;
The given query uses the json:group function to aggregate the JSON objects from the InputStream within a sliding window of five events. Given the input events:
{"date":"2013-11-19","time":"10:30"}{"date":"2013-11-19","time":"12:20"}
The output groupedJSONArray contains:
[{"date":"2013-11-19","time":"10:30"}, {"date":"2013-11-19","time":"12:20"}]
This aggregated result is sent to the OutputStream.
Example 2
@info(name = 'query1')
SELECT json:group("json", true) AS groupedJSONArray
FROM InputStream WINDOW SLIDING_LENGTH(5)
INPUT OutputStream;
The given query uses the json:group function with true as the second parameter to aggregate the unique JSON objects from the InputStream within a sliding window of five events. Given the input events:
{"date":"2013-11-19","time":"10:30"}{"date":"2013-11-19","time":"10:30"}
The output groupedJSONArray contains:
[{"date":"2013-11-19","time":"10:30"}]
This aggregated result is sent to the OutputStream.
Example 3
@info(name = 'query1')
SELECT json:group("json", "result") AS groupedJSONArray
FROM InputStream WINDOW SLIDING_LENGTH(5)
INPUT OutputStream;
The given query uses the json:group function with "result" as the second parameter to aggregate the JSON objects from the InputStream within a sliding window of five events and creates a JSON object with a key named "result". Given the input events:
{"date":"2013-11-19","time":"10:30"}{"date":"2013-11-19","time":"12:20"}
The output groupedJSONArray contains:
{"result":[{"date":"2013-11-19","time":"10:30"},{"date":"2013-11-19","time":"12:20"}}
This aggregated result is sent to the OutputStream.
Example 4
@info(name = 'query1')
SELECT json:group("json", "result", true) AS groupedJSONArray
FROM InputStream WINDOW SLIDING_LENGTH(5)
INPUT OutputStream;
The given query uses the json:group function with the parameters "result" and true to aggregate unique JSON objects from the InputStream within a sliding window of five events and creates a JSON object with a key named "result". Given the input events:
{"date":"2013-11-19","time":"10:30"}{"date":"2013-11-19","time":"10:30"}
The output groupedJSONArray contains:
{"result":[{"date":"2013-11-19","time":"10:30"}]}
Since the true parameter is used, only unique JSON objects are included in the result. This aggregated result is sent to the OutputStream.