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From Neeraja Rentachintala <nrentachint...@maprtech.com>
Subject Re: Query a field with empty list
Date Mon, 02 Nov 2015 20:55:01 GMT
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 <hyichu@maprtech.com> 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 <zfong@maprtech.com> 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 <hyichu@maprtech.com>
> 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 <
> > > aengelbrecht@maprtech.com> 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 <hyichu@maprtech.com>
> > 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.
> > > >
> > > >
> > >
> >
>

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