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From Hsuan Yi Chu <hyi...@maprtech.com>
Subject Re: Query a field with empty list
Date Mon, 02 Nov 2015 19:53:24 GMT
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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