Multiplied rows in impala

Question

I am fetching some data from a view with some joined tables through sqoop into an external table in impala. However I saw that the columns from one table multiply the rows. For example

id first_name surname step name       value
1  ted         kast    1   museum     visitor
1  ted         kast    1   shop       buyer
1  ted         kast    2   museum     visitor
1  ted         kast    2   shop       buyer

But I want to be something like that

id first_name surname step name_value
1  ted        kast    1    [(museum visitor), (shop buyer)]
1  ted        kast    2    [(museum visitor), (shop buyer)]

How can I achieve that in impala?

Answer 1

We can use aggregation here along with GROUP_CONCAT:

SELECT
    id,
    first_name,
    surname,
    step,
    CONCAT('[', GROUP_CONCAT(CONCAT('(', CONCAT_WS(' ', name, value), ')'), ', '), ']') AS name_value
FROM yourTable
GROUP BY
    id,
    first_name,
    surname,
    step
ORDER BY id;

Here is a demo for MySQL, where the syntax is almost the same as for Impala.