Seems empty list is getting the vote for select. For consistency would it then make sense to have flatten produce a single row with an empty list in the result?
—Andries > On Nov 2, 2015, at 12:55 PM, Neeraja Rentachintala > <[email protected]> wrote: > > Empty list sounds like the appropriate thing. > What would be the result of we do flatten on this list? > I think user should get a row back in the results. > > > > On Mon, Nov 2, 2015 at 11:53 AM, Hsuan Yi Chu <[email protected]> wrote: > >> I agree. I think in any context, empty list should appear as [] in the >> result. >> >> Any opposition? >> >> On Mon, Nov 2, 2015 at 11:50 AM, Zelaine Fong <[email protected]> wrote: >> >>> Wouldn't it make more sense to return an empty list in this case? Null >> is >>> not quite the same as an empty list. So, I would think you'd want a >>> distinction between the two. >>> >>> -- Zelaine >>> >>> On Mon, Nov 2, 2015 at 11:41 AM, Hsuan Yi Chu <[email protected]> >> wrote: >>> >>>> There could be inconsistent results: >>>> https://issues.apache.org/jira/browse/DRILL-4007 >>>> >>>> On Mon, Nov 2, 2015 at 8:17 AM, Andries Engelbrecht < >>>> [email protected]> wrote: >>>> >>>>> Currently in 1.2 I observe the following. >>>>> >>>>> 0: jdbc:drill:> select a from dfs.json.`/test.json`; >>>>> +-------+ >>>>> | a | >>>>> +-------+ >>>>> | null | >>>>> +———+ >>>>> >>>>> But then flatten produces an error >>>>> >>>>> 0: jdbc:drill:> select flatten(a) from dfs.json.`/test.json`; >>>>> Error: SYSTEM ERROR: ClassCastException: Cannot cast >>>>> org.apache.drill.exec.vector.NullableIntVector to >>>>> org.apache.drill.exec.vector.complex.RepeatedValueVector >>>>> >>>>> Ideally both should return similar responses, in most cases it may be >>>>> easier to work with a null being returned than no record or an empty >>>>> string. Returning [] might be interpreted as a string data type >> pending >>>>> user experience or tools being used?? >>>>> >>>>> —Andries >>>>> >>>>> >>>>> >>>>>> On Oct 31, 2015, at 4:44 PM, Hsuan Yi Chu <[email protected]> >>> wrote: >>>>>> >>>>>> Hi, >>>>>> For example, say, we are querying a field with empty list: >>>>>> >>>>>> select a from `XXX,json` >>>>>> >>>>>> { >>>>>> a: [] >>>>>> } >>>>>> >>>>>> What is the expected result in the sqlline? Which one of the >>> following >>>>>> should it be? >>>>>> >>>>>> 1. [] >>>>>> 2. null >>>>>> 3. no record >>>>>> >>>>>> Thanks. >>>>> >>>>> >>>> >>> >>
