[jira] [Created] (FLINK-8951) Support OVER windows PARTITION BY (rounded) timestamp

["Fabian Hueske (JIRA)" <ji...@apache.org>]

Fabian Hueske created FLINK-8951:
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             Summary: Support OVER windows PARTITION BY (rounded) timestamp
                 Key: FLINK-8951
                 URL: https://issues.apache.org/jira/browse/FLINK-8951
             Project: Flink
          Issue Type: New Feature
          Components: Table API & SQL
            Reporter: Fabian Hueske


There are a few interesting use cases that can be addressed by queries that follow the following pattern

{code:sql}
SELECT sensorId COUNT(*) OVER (PARTITION BY CEIL(rowtime TO HOUR) ORDER BY temp ROWS BETWEEN UNBOUNDED preceding AND CURRENT ROW) FROM sensors
{code}

Such queries can be used to compute rolling cascading (tumbling) windows with aggregates that are reset in regular intervals. This can be useful for TOP-K per minute/hour/day queries.

Right now, such {{OVER}} windows are not supported, because we require that the {{ORDER BY}} clause is defined on a timestamp (time indicator) attribute. In order to support this kind of queries, we would require that the {{PARTITION BY}} clause contains a timestamp (time indicator) attribute or a function that is defined on it and which is monotonicity preserving. Once the optimizer identifies this case, it could translate the query into a special time-partitioned OVER window operator.



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