Handling Missing Values | Teradata Vantage - 17.10 - Handling Missing Values within a Timebucket - Advanced SQL Engine - Teradata Database

Teradata Vantageā„¢ - Time Series Tables and Operations

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Programming Reference
Publication ID
B035-1208-171K
Language
English (United States)

When a missing value is present within a timebucket (for example, the NULL value inserted in the TEMPERATURE column in Table and Data Definition for Time Series Aggregates Examples), the value is ignored and it is not included in the calculation of the aggregate result. This is consistent with the behavior of existing aggregate functions in Vantage.

The example shows the result of an AVERAGE with NULL values:

SELECT $TD_TIMECODE_RANGE, $TD_GROUP_BY_TIME, BUOYID, AVG(TEMPERATURE), COUNT(*)
FROM OCEAN_BUOYS
WHERE TD_TIMECODE BETWEEN TIMESTAMP '2014-01-06 08:00:00' AND TIMESTAMP '2014-01-06 10:30:00'
AND BUOYID = 0
GROUP BY TIME (MINUTES(10) AND BUOYID)
ORDER BY 2,3;

Result:

TIMECODE_RANGE GROUP BY TIME(MINUTES(10)) BUOYID Average(TEMPERATURE) COUNT(*)
('2014-01-06 08:00:00.000000+00:00', '2014-01-06 08:10:00.000000+00:00') 1 0 54 3
('2014-01-06 08:10:00.000000+00:00', '2014-01-06 08:20:00.000000+00:00') 2 0 55 2

The null value was omitted from the result calculation.

If this behavior is not desired there are strategies to clean the series data so the missing values are removed or updated with a value. For more information on these strategies, see: