If I do a query with a

where mvfield in ('a', 'b') group by mvfield

, and

mvfield

is a multi-valued field, I get a result with groups for values from

mvfield

that aren’t in my where clause. I assume I’m getting groups for every value found in

mvfield

from rows where

mvfield

contains a match for my filter, but it seems wrong…am I missing something?

You need the

value_in

udf. Let me find an example

Thanks for the hint, found an example in the code. Should be

select VALUEIN(mvfield, 'a', 'b') as groups from table group by groups

Yeah, there you go

Where should I add documentation for this UDF?

Seems the doc exists: https://docs.pinot.apache.org/users/user-guide-query/supported-transformations#multi-value-column-functions

OK - I was looking in documentation about grouping. So maybe a note there about when grouping on a multi-valued field that’s also been used for filtering?

yeah, makes sense