select unnest(), unnest()

Hi, we have some queries that use unnest() function.

create table configuration (

id int,

advisor text,

branch text,

primary key(id)

);

insert into configuration values

(1,'a','00,01'),

(2,'a','00'),

(3,'b','02,03'),

(4,'c','05'),

(5,'d,e','00,01');

select id, unnest(string_to_array(advisor,',')), unnest
(string_to_array(branch,','))

from configuration;


PG9.6:

id | unnest | unnest

----+--------+--------

  1 | a      | 00

  1 | a      | 01

  2 | a      | 00

  3 | b      | 02

  3 | b      | 03

  4 | c      | 05

  5 | d      | 00

  5 | e      | 01

PG10:

id | unnest | unnest

----+--------+--------

  1 | a      | 00

  1 |        | 01

  2 | a      | 00

  3 | b      | 02

  3 |        | 03

  4 | c      | 05

  5 | d      | 00

  5 | e      | 01


- Is this wanted in PG10 or a bug?
- Is there a way to change the behaviour of pgsql to produce output like
9.6?
- A smooth sql-workaround?

Thank you very much!

Regards, Jasmin