Event Types

Query output depends on the current and expired event types it produces based on its internal processing state. By default all queries produce current events upon event arrival to the query. The queries containing windows additionally produce expired events when events expire from the windows.

Purpose

Event type helps to specify when a query should output events to the stream, such as output upon current events, expired events or upon both current and expired events.

Syntax

Syntax for event types varies on what keywords you are using.

INSERT INTO

Event type should be defined in between INSERT and INTO keywords for insert queries as follows.

INSERT <event type> INTO <output stream>
SELECT <attribute name>, <attribute name>, ...
FROM <input stream> WINDOW <window name>(<parameter>, <parameter>, ... )

DELETE

Event type should be defined next to the FOR keyword for delete queries as follows.

DELETE <table> (for <event type>)?
    ON <condition>
SELECT <attribute name>, <attribute name>, ...
FROM <input stream> WINDOW <window name>(<parameter>, <parameter>, ... )

UPDATE

Event type should be defined next to the FOR keyword for update queries as follows.

UPDATE <table> (for <event type>)?
    SET <table>.<attribute name> = (<attribute name>|<expression>)?, <table>.<attribute name> = (<attribute name>|<expression>)?, ...
    ON <condition>
SELECT <attribute name>, <attribute name>, ...
FROM <input stream> WINDOW <window name>(<parameter>, <parameter>, ... )

UPDATE OR INSERT

Event type should be defined next to the FOR keyword for update or insert queries as follows.

UPDATE OR INSERT INTO <table> (for <event type>)?
    SET <table>.<attribute name> = <expression>, <table>.<attribute name> = <expression>, ...
    ON <condition>
SELECT <attribute name>, <attribute name>, ...
FROM <input stream> WINDOW <window name>(<parameter>, <parameter>, ... )

note

Controlling query output based on the event types neither alters query execution nor its accuracy.

Parameters

The event types can be defined using the following keywords to manipulate query output.

Event Types	Description
current events	Outputs events only when incoming events arrive to be processed by the query. This is default behavior when no specific event type is specified.
expired events	Outputs events only when events expires from the window.
all events	Outputs events when incoming events arrive to be processed by the query as well as when events expire from the window.

Example

Query to output only the expired events from a one-minute time window to DelayedTempStream. This can be used for delaying the events by a minute.

INSERT expired events INTO DelayedTempStream
SELECT *
FROM TempStream WINDOW SLIDING_TIME(1)

note

This is just to illustrate how expired events work. Use the DELAY window for use cases where we need to delay events by a given time period.