Currently displaying complex types is not supported in Impala. There is a workaround to see the unnested content of the collections but there is no such functionality to display one complex type in one result column formatted to Json. Note, Hive does have support for the same.
The scope of this Jira is to have an umbrella for the following tasks:
- Support all complex types (Struct, Array, Map) in the SELECT list and display them as Json.
- Display complex type columns in Json for a "SELECT *" query
- Allow returning complex types in a sub-select
- Have the display support for Parquet and ORC
Note, I made the sub-tasks as small as possible so that this granularity allows to parallelise the work.