[FLINK-19076] Import rule to deal Temporal Join condition

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Resolved
• Component/s: Table SQL / Planner
• Assignee: Leonard Xu
• Reporter: Leonard Xu
• Created: 28/Aug/20 03:40
• Updated: 16/Oct/20 15:50
• Resolved: 16/Oct/20 15:50

Description

Temporal join is a correlate, the right of correlate is a Snapshot, the period of snapshot comes from left table's time attribute column. 

the time attribute column may be pruned if the downstream `RelNode` did not reference it any more, so I need to keep the necessary  condition(e.g., left time attribute, right primary key) for temporal join node in join condition.

Given an example:

SELECT o.order_id, o.currency, o.amount, r.rate,r.rowtime 
 FROM orders_proctime AS o JOIN 
 versioned_currency 
 FOR SYSTEM_TIME AS OF o.rowtime as r 
 ON o.currency = r.currency

The select clause did not use `o.rowtime` and thus the column `o.rowtime` will be removed later, but we need the `o.rowtime` in temporal join node, so I keep the `o.rowtime` in temporal join condition just like[1].

[1] https://github.com/apache/flink/blob/c601cfd662c2839f8ebc81b80879ecce55a8cbaf/flink-table/flink-table-planner-blink/src/main/scala/org/apache/flink/table/planner/plan/utils/TemporalJoinUtil.scala 

 

Issue Links

• links to: https://github.com/apache/flink/pull/13299