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https://issues.apache.org/jira/browse/DRILL-3562?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15357603#comment-15357603
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F Méthot commented on DRILL-3562:
---------------------------------
Really would like to see this one fixed!
Here is a workaround we are doing to get to our data:
This will extract data without the null arrays:
select t.a.b.c as c from dfs.`flat.json` t where t.a.b.c[0]['d'] is not null
(d is an value name expected to be found within the array)
but flatten still won't work:
To get flatten working:
create table TEMP_JSON_DATA as (select t.a.b.c as c from dfs..`flat.json`
t where t.a.b.c[0]['d'] is not null);
then
select flatten(c) from TEMP_JSON_DATA;
(using parquet format for temp table)
For interactive analysis of data, is a pretty lame workaround, but for
scripting environment that worked out fine, if you automate dropping of the
temp table.
> Query fails when using flatten on JSON data where some documents have an
> empty array
> ------------------------------------------------------------------------------------
>
> Key: DRILL-3562
> URL: https://issues.apache.org/jira/browse/DRILL-3562
> Project: Apache Drill
> Issue Type: Bug
> Components: Storage - JSON
> Affects Versions: 1.1.0
> Reporter: Philip Deegan
> Fix For: Future
>
>
> Drill query fails when using flatten when some records contain an empty array
> {noformat}
> SELECT COUNT(*) FROM (SELECT FLATTEN(t.a.b.c) AS c FROM dfs.`flat.json` t)
> flat WHERE flat.c.d.e = 'f' limit 1;
> {noformat}
> Succeeds on
> { "a": { "b": { "c": [ { "d": { "e": "f" } } ] } } }
> Fails on
> { "a": { "b": { "c": [] } } }
> Error
> {noformat}
> Error: SYSTEM ERROR: ClassCastException: Cannot cast
> org.apache.drill.exec.vector.NullableIntVector to
> org.apache.drill.exec.vector.complex.RepeatedValueVector
> {noformat}
> Is it possible to ignore the empty arrays, or do they need to be populated
> with dummy data?
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