Fabian Hueske created FLINK-5653:
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Summary: Add processing time OVER ROWS BETWEEN x PRECEDING
aggregation to SQL
Key: FLINK-5653
URL: https://issues.apache.org/jira/browse/FLINK-5653
Project: Flink
Issue Type: Sub-task
Components: Table API & SQL
Reporter: Fabian Hueske
The goal of this issue is to add support for OVER ROW aggregations on
processing time streams to the SQL interface.
Queries similar to the following should be supported:
{code}
SELECT
a,
SUM(b) OVER (PARTITION BY c ROW BETWEEN 2 PRECEDING AND CURRENT ROW) AS sumB,
MIN(b) OVER (PARTITION BY c ROW BETWEEN 2 PRECEDING AND CURRENT ROW) AS minB
FROM myStream
{code}
The following restrictions should initially apply:
- All OVER clauses in the same SELECT clause must be exactly the same.
- The PARTITION BY clause is optional (no partitioning results in single
threaded execution).
- The ORDER BY clause may not be used (this distinguishes processing time from
event time which requires an ORDER BY clause on a special field).
- UNBOUNDED PRECEDING is not supported
- FOLLOWING is not supported.
The restrictions will be resolved in follow up issues. If we find that some of
the restrictions are trivial to address, we can add the functionality in this
issue as well.
This issue includes:
- Design of the DataStream operator to compute OVER ROW aggregates
- Translation from Calcite's RelNode representation (LogicalProject with
RexOver expression).
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