kslack (Stream Processor)
Stream processor performs reordering of out-of-order events using K-Slack algorithm.
Syntax
reorder:kslack(<LONG> timestamp)
reorder:kslack(<LONG> timestamp, <LONG> timeout)
reorder:kslack(<LONG> timestamp, <BOOL> discard.late.arrival)
reorder:kslack(<LONG> timestamp, <LONG> timeout, <LONG> max.k)
reorder:kslack(<LONG> timestamp, <LONG> timeout, <BOOL> discard.late.arrival)
reorder:kslack(<LONG> timestamp, <LONG> timeout, <LONG> max.k, <BOOL> discard.late.arrival)
Query Parameters
| Name | Description | Default Value | Possible Data Types | Optional | Dynamic |
|---|---|---|---|---|---|
| timestamp | The event timestamp on which the events should be ordered. | LONG | No | Yes | |
| timeout | A timeout value in milliseconds, where the buffered events who are older than the given timeout period get flushed every second. | -1 (timeout is infinite) | LONG | Yes | No |
| max.k | The maximum K-Slack window threshold (K parameter). | 9,223,372,036,854,775,807 (The maximum Long value) | LONG | Yes | No |
| discard.late.arrival | If set to true the processor would discarded the out-of-order events arriving later than the K-Slack window, and in otherwise it allows the late arrivals to proceed. | false | BOOL | Yes | No |
Example 1
CREATE STREAM StockStream (eventTime long, symbol string, volume long);
@info(name = 'query1')
insert into OutputStream
select eventTime, symbol, volume
from StockStream#reorder:kslack(eventTime, 5000);
The query reorders events based on the eventTime attribute value, and it forcefully flushes all the events who have arrived older than the given timeout value (5000 milliseconds) every second.