John,
I don't understand what you are seeing. Here is what I am seeing (and
hopefully you can tell what I am missing).
First the input is:
$ cat x.json
{"b":1, "a":[] }
{"a":[1,2], "b":3}
And then with this input, I get this:
0: jdbc:drill:> select * from dfs.tdunning.`x.json`;
+----+------------+
| b | a |
+----+------------+
| 1 | [] |
| 3 | ["1","2"] |
+----+------------+
2 rows selected (0.443 seconds)
0: jdbc:drill:> select a,b from dfs.tdunning.`x.json`;
+------------+----+
| a | b |
+------------+----+
| [] | 1 |
| ["1","2"] | 3 |
+------------+----+
2 rows selected (0.473 seconds)
0: jdbc:drill:> select flatten(a),b from dfs.tdunning.`x.json`;
+---------+----+
| EXPR$0 | b |
+---------+----+
| 1 | 3 |
| 2 | 3 |
+---------+----+
2 rows selected (0.499 seconds)
On Mon, Oct 19, 2015 at 7:03 AM, John Omernik <[email protected]> wrote:
> In https://drill.apache.org/docs/json-data-model/ there is a section that
> goes as laid out below. This is actually not occurring for me. I have a
> json dump from Mongo that has a field called tags where many records have
> "tags":[] and it's outputting that without error. (It just shows [] as the
> output).
>
> So, my question is this... based on the documentation, what I am seeing is
> NOT expected, is it a miss on the docs, or something that is fixed in the
> 1.2 release that I have?
>
> If it is fixed so we can have empty arrays in a field like tags, is it
> possible there are some functions I can use to determine if that field is
> empty? i.e. if isemptyarray(tags) returns true if empty or perhaps get me
> the length said array? These functions would be very valuable in queries
> (if the empty arrays thing is not a weird quirk I am seeing).
>
> Empty array
>
> Drill cannot read an empty array, shown in the following example, and
> attempting to do so causes an error.
>
> { "a":[] }
>
> Workaround: Remove empty arrays.
>
