Hi all, the related issue:https://issues.apache.org/jira/browse/FLINK-15573
As the title tells, what I do want to do is let the `FieldRefrence` use Unicode as its default charset (or maybe as an optional charset which can be configured). According to the `PlannerExpressionParserImpl`, currently FLINK uses JavaIdentifier as `FieldRefrence`??s default charset. But, from my perspective, it is not enough. Considering that user who uses ElasticSearch as sink??we all know that ES has A field called `@timestamp`, which JavaIdentifier cannot meet. So in my team, we just let `PlannerExpressionParserImpl#FieldRefrence` use Unicode as its default charset so that solves this kind of problem. (Plz refer to the issue I mentioned above ) In my Opinion, the change shall be for general purpose: Firstly, Mysql supports unicode as default field charset, see the field named `@@`, so shall we support unicode also? What?? s more, my team really get a lot of benefits from this change. I also believe that it can give other users more benefits without even any harm! Fortunately, the change supports fully forwards compatibility.Cuz Unicode is the superset of JavaIdentifier. Only a few code change can achieve this goal. Looking forward for any opinion. btw, thanks to tison~ Best Regards ??????Shoi Liu
