Window Queries
This page explains how to use windows in queries.
To learn about different types of windows, refer to Window Types
Syntax
If you are using a named window defined with a CREATE statement, then you can use the following syntax:
INSERT INTO <output stream>
SELECT <attribute name>, <attribute name>, ...
FROM <window>
You can also define the window by using the window <window-name> next to the input stream:
INSERT <output event type>? INTO <output stream>
SELECT <attribute name>, <attribute name>, ...
FROM <input stream> WINDOW <window name>(<parameter>, <parameter>, ... );
Filter conditions can be applied both before and/or after the window.
Example 1
CREATE WINDOW FiveMinTempWindow (roomNo int, temp double) time(5 min);
INSERT INTO MaxSensorReadingStream
SELECT max(temp) as maxValue, roomNo
FROM FiveMinTempWindow;
This stream worker calculates the maximum temperature within the last five minutes.
Example 2
Query to find out the maximum temperature out of the last 10 events, using the window of SLIDING_LENGTH 10 and max() aggregation function, from the TempStream stream and insert the results into the MaxTempStream stream.
INSERT INTO MaxTempStream
SELECT max(temp) AS maxTemp
FROM TempStream WINDOW SLIDING_LENGTH(10);
Here, the SLIDING_LENGTH window operates in a sliding manner where the following three event subsets are calculated and outputted when a list of 12 events are received in sequential order.
| Subset | Event Range |
|---|---|
| 1 | 1 - 10 |
| 2 | 2 - 11 |
| 3 | 3 - 12 |
Example 3
Query to find out the maximum temperature out of the every 10 events, using the window of TUMBLING_LENGTH 10 and max() aggregation function, from the TempStream stream and insert the results into the MaxTempStream stream.
INSERT INTO MaxTempStream
SELECT max(temp) AS maxTemp
FROM TempStream WINDOW TUMBLING_LENGTH(10);
Here, the window operates in a batch (tumbling) manner where the following three event subsets are calculated and outputted when a list of 30 events are received in a sequential order.
| Subset | Event Range |
|---|---|
| 1 | 1 - 10 |
| 2 | 11 - 20 |
| 3 | 21 - 30 |
Example 4
Query to find out the maximum temperature out of the events arrived during last 10 minutes, using the window of SLIDING_TIME 10 minutes and max() aggregation function, from the TempStream stream and insert the results into the MaxTempStream stream.
INSERT INTO MaxTempStream
SELECT max(temp) AS maxTemp
FROM TempStream WINDOW SLIDING_TIME(10 min);
Here, the time window operates in a sliding manner with millisecond accuracy, where it will process events in the following three time durations and output aggregated events when a list of events are received in a sequential order.
| Subset | Time Range (in ms) |
|---|---|
| 1 | 1:00:00.001 - 1:10:00.000 |
| 2 | 1:00:01.001 - 1:10:01.000 |
| 3 | 1:00:01.033 - 1:10:01.034 |
Example 5
Query to find out the maximum temperature out of the events arriving every 10 minutes, using the window of TUMBLING_TIME 10 and max() aggregation function, from the TempStream stream and insert the results into the MaxTempStream stream.
INSERT INTO MaxTempStream
SELECT max(temp) AS maxTemp
FROM TempStream WINDOW TUMBLING_TIME(10 min);
Here, the window operates in a batch (tumbling) manner where the window will process events in the following three time durations and output aggregated events when a list of events are received in a sequential order.
| Subset | Time Range (in ms) |
|---|---|
| 1 | 1:00:00.001 - 1:10:00.000 |
| 2 | 1:10:00.001 - 1:20:00.000 |
| 3 | 1:20:00.001 - 1:30:00.000 |