Hi Jingsong,
thanks for writing down this FLIP. Big +1 from my side to finally get
rid of PlannerExpressions and have consistent and well-defined behavior
for Table API and SQL updated to FLIP-37.
We might need to discuss some of the behavior of particular functions
but this should not affect the actual FLIP-51.
Regards,
Timo
Am 13.08.19 um 12:55 schrieb JingsongLee:
Hi everyone,
We would like to start a discussion thread on "FLIP-51: Rework of the
Expression Design"(Design doc: [1], FLIP: [2]), where we describe how
to improve the new java Expressions to work with type inference and
convert expression to the calcite RexNode. This is a follow-up plan
for FLIP-32[3] and FLIP-37[4]. This FLIP is mostly based on FLIP-37.
This FLIP addresses several shortcomings of current:
- New Expressions still use PlannerExpressions to type inference and
to RexNode. Flnk-planner and blink-planner have a lot of repetitive code
and logic.
- Let TableApi and Cacite definitions consistent.
- Reduce the complexity of Function development.
- Powerful Function for user.
Key changes can be summarized as follows:
- Improve the interface of FunctionDefinition.
- Introduce type inference for built-in functions.
- Introduce ExpressionConverter to convert Expression to calcite
RexNode.
- Remove repetitive code and logic in planners.
I also listed type inference and behavior of all built-in functions [5], to
verify that the interface is satisfied. After introduce type inference to
table-common module, planners should have a unified function behavior.
And this gives the community also the chance to quickly discuss types
and behavior of functions a last time before they are declared stable.
Looking forward to your feedbacks. Thank you.
[1]
https://docs.google.com/document/d/1yFDyquMo_-VZ59vyhaMshpPtg7p87b9IYdAtMXv5XmM/edit?usp=sharing
[2]
https://cwiki.apache.org/confluence/display/FLINK/FLIP-51%3A+Rework+of+the+Expression+Design
[3]
https://cwiki.apache.org/confluence/display/FLINK/FLIP-32%3A+Restructure+flink-table+for+future+contributions
[4]
https://cwiki.apache.org/confluence/display/FLINK/FLIP-37%3A+Rework+of+the+Table+API+Type+System
[5]
https://docs.google.com/document/d/1fyVmdGgbO1XmIyQ1BaoG_h5BcNcF3q9UJ1Bj1euO240/edit?usp=sharing
Best,
Jingsong Lee
