TimestampRepair

This function is used for timestamp repair. According to the given standard time interval, the method of minimizing the repair cost is adopted. By fine-tuning the timestamps, the original data with unstable timestamp interval is repaired to strictly equispaced data. If no standard time interval is given, this function will use the median, mode or cluster of the time interval to estimate the standard time interval.

Name: TIMESTAMPREPAIR

Input Series: Only support a single input series. The data type is INT32 / INT64 / FLOAT / DOUBLE.

Parameters:

• interval: The standard time interval whose unit is millisecond. It is a positive integer. By default, it will be estimated according to the given method.
• method: The method to estimate the standard time interval, which is 'median', 'mode' or 'cluster'. This parameter is only valid when interval is not given. By default, median will be used.

Output Series: Output a single series. The type is the same as the input. This series is the input after repairing.

Examples

Manually Specify the Standard Time Interval

When interval is given, this function repairs according to the given standard time interval.

Input series:

+-----------------------------+---------------+
|                         Time|root.test.d2.s1|
+-----------------------------+---------------+
|2021-07-01T12:00:00.000+08:00|            1.0|
|2021-07-01T12:00:10.000+08:00|            2.0|
|2021-07-01T12:00:19.000+08:00|            3.0|
|2021-07-01T12:00:30.000+08:00|            4.0|
|2021-07-01T12:00:40.000+08:00|            5.0|
|2021-07-01T12:00:50.000+08:00|            6.0|
|2021-07-01T12:01:01.000+08:00|            7.0|
|2021-07-01T12:01:11.000+08:00|            8.0|
|2021-07-01T12:01:21.000+08:00|            9.0|
|2021-07-01T12:01:31.000+08:00|           10.0|
+-----------------------------+---------------+

SQL for query:

select timestamprepair(s1,'interval'='10000') from root.test.d2

Output series:

+-----------------------------+----------------------------------------------------+
|                         Time|timestamprepair(root.test.d2.s1, "interval"="10000")|
+-----------------------------+----------------------------------------------------+
|2021-07-01T12:00:00.000+08:00|                                                 1.0|
|2021-07-01T12:00:10.000+08:00|                                                 2.0|
|2021-07-01T12:00:20.000+08:00|                                                 3.0|
|2021-07-01T12:00:30.000+08:00|                                                 4.0|
|2021-07-01T12:00:40.000+08:00|                                                 5.0|
|2021-07-01T12:00:50.000+08:00|                                                 6.0|
|2021-07-01T12:01:00.000+08:00|                                                 7.0|
|2021-07-01T12:01:10.000+08:00|                                                 8.0|
|2021-07-01T12:01:20.000+08:00|                                                 9.0|
|2021-07-01T12:01:30.000+08:00|                                                10.0|
+-----------------------------+----------------------------------------------------+

Automatically Estimate the Standard Time Interval

When interval is default, this function estimates the standard time interval.

Input series is the same as above, the SQL for query is shown below:

select timestamprepair(s1) from root.test.d2

Output series:

+-----------------------------+--------------------------------+
|                         Time|timestamprepair(root.test.d2.s1)|
+-----------------------------+--------------------------------+
|2021-07-01T12:00:00.000+08:00|                             1.0|
|2021-07-01T12:00:10.000+08:00|                             2.0|
|2021-07-01T12:00:20.000+08:00|                             3.0|
|2021-07-01T12:00:30.000+08:00|                             4.0|
|2021-07-01T12:00:40.000+08:00|                             5.0|
|2021-07-01T12:00:50.000+08:00|                             6.0|
|2021-07-01T12:01:00.000+08:00|                             7.0|
|2021-07-01T12:01:10.000+08:00|                             8.0|
|2021-07-01T12:01:20.000+08:00|                             9.0|
|2021-07-01T12:01:30.000+08:00|                            10.0|
+-----------------------------+--------------------------------+