JOIN query with functions in SELECT field is not supported

[chloe-zh]

JOIN queries with aggregations in SELECT field are supported, but it is not supported if placed with basic functions (math functions, string operators etc.)

Example:

select substring(a.firstname), d.dog_name from people2 a join dogs2 d on a.firstname = d.holdersName where (a.age > 10 or a.balance > 2000) and d.age > 1

Result:

{
  "error": {
    "reason": "There was internal problem at backend",
    "details": "Error happened during execution",
    "type": "IllegalStateException"
  },
  "status": 500
}

And the log recorded: No field found for [a.firstname] in mapping with types []

Result from MySql:

substring(firstname, 1, 2)    dog_name
Da    rex
Ha    snoopy