[FLINK-5804] Add [non-partitioned] processing time OVER RANGE BETWEEN UNBOUNDED PRECEDING aggregation to SQL

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Implemented
• Fix Version/s: 1.3.0
• Component/s: Table SQL / API
• Assignee: sunjincheng
• Reporter: sunjincheng
• Created: 15/Feb/17 06:08
• Updated: 09/Mar/17 18:13
• Resolved: 09/Mar/17 18:13

Description

The goal of this issue is to add support for OVER RANGE aggregations on processing time streams to the SQL interface.

Queries similar to the following should be supported:

SELECT 
  a, 
  SUM(b) OVER (ORDER BY procTime() RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS sumB,
  MIN(b) OVER (ORDER BY procTime() RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS minB
FROM myStream

The following restrictions should initially apply:

• All OVER clauses in the same SELECT clause must be exactly the same.
• Since no PARTITION BY clause is specified, the execution will be single threaded.
• The ORDER BY clause may only have procTime() as parameter. procTime() is a parameterless scalar function that just indicates processing time mode.
• bounded PRECEDING is not supported (see FLINK-5654)
• 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).

Issue Links

• depends upon: FLINK-4460 Side Outputs in Flink
• links to: GitHub Pull Request #3491