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From Hsuan Yi Chu <hyi...@maprtech.com>
Subject Re: Query a field with empty list
Date Mon, 02 Nov 2015 19:41:29 GMT
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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