merge (Aggregate Function)

Collects multiple lists to merge as a single list.

Syntax

<OBJECT> list:merge(<OBJECT> list)
<OBJECT> list:merge(<OBJECT> list, <BOOL> is.distinct)

Query Parameters

Name	Description	Default Value	Possible Data Types	Optional	Dynamic
list	List to be merged		OBJECT	No	Yes
is.distinct	Whether to return list with distinct values	false	BOOL	Yes	Yes

Example 1

INSERT INTO OutputStream
SELECT list:merge(list) AS stockSymbols
FROM StockStream WINDOW TUMBLING_LENGTH(2);

In this query, the StockStream contains events with an attribute list of type ARRAY<string>. The query processes events using a tumbling window of length 2, which means that it groups events in non-overlapping sets of two.

For each set of two events within the tumbling window, the list:merge(list) function is applied. This function takes the list attributes from both events and merges their elements into a single, combined list.

The merged list is then aliased as stockSymbols and inserted into the OutputStream. As a result, the OutputStream will contain events with combined lists from every pair of consecutive events in the StockStream.

Example 2

CREATE STREAM StockStream (list OBJECT);
CREATE SINK STREAM OutputStream (stockSymbols OBJECT);

@info(name = 'MergeList')
INSERT INTO OutputStream
SELECT list:merge(list) AS stockSymbols
FROM StockStream WINDOW TUMBLING_LENGTH(2);

In this stream worker, an input stream StockStream is defined, which contains a list of stock symbols. The function list:merge(list) operates on a tumbling window of length 2 on the StockStream. This function processes the list attribute from every two events and merges them into a single list. The merged list is then aliased as stockSymbols and inserted into the OutputStream. Consequently, OutputStream contains combined lists from every pair of consecutive events in the StockStream.