Flink sql join问题

可以试下最新flink 1.9 blink planner的firstRow/lastRow优化[1]能否满足你的需求，目前的限制是只能基于procTime来去重。

• e.g.
• 1. {{{
• SELECT a, b, c FROM (
• SELECT a, b, c, proctime,
• ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime ASC) as row_num
• FROM MyTable
• ) WHERE row_num <= 1
• }}} will be converted to StreamExecDeduplicate which keeps first row.
• 1. {{{
• SELECT a, b, c FROM (
• SELECT a, b, c, proctime,
• ROW_NUMBER() OVER (PARTITION BY a ORDER BY proctime DESC) as row_num
• FROM MyTable
• ) WHERE row_num <= 1
• }}} will be converted to StreamExecDeduplicate which keeps last row.

[1] https://github.com/apache/flink/blob/master/flink-table/flink-table-planner-blink/src/main/scala/org/apache/flink/table/planner/plan/rules/physical/stream/StreamExecDeduplicateRule.scala*来自志愿者整理的flink邮件归档