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Posted to notifications@iotdb.apache.org by "Yuan Tian (Jira)" <ji...@apache.org> on 2022/11/21 02:16:00 UTC

[jira] [Created] (IOTDB-5000) Implement a new built-in function DIFFERENCE

Yuan Tian created IOTDB-5000:
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             Summary: Implement a new built-in function DIFFERENCE
                 Key: IOTDB-5000
                 URL: https://issues.apache.org/jira/browse/IOTDB-5000
             Project: Apache IoTDB
          Issue Type: New Feature
            Reporter: Yuan Tian
            Assignee: 李伟豪


Returns the result of subtraction between subsequent column values;

You can refer to influxDB ([https://docs.influxdata.com/influxdb/v2.5/query-data/influxql/functions/transformations/#difference)]

Actually, this function is a substitution for window function lag and lead.

We should decide to how to deal with null value, so before starting, you should figure out how other dbs deal with that like InfluxDB, TimescaleDB(using lag and lead windows function to mimic).



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