Re: Custom sort order with jsonb key

On Thu, Jun 23, 2016 at 12:03 PM, David G. Johnston <
david(dot)g(dot)johnston(at)gmail(dot)com> wrote:

> On Thu, Jun 23, 2016 at 2:38 PM, Anton Ananich <anton(dot)ananich(at)gmail(dot)com>
> wrote:
>
>> Dear colleagues,
>>
>> I have a table in PostgreSQL with some data:
>>
>> create table FOO (
>> key jsonb
>> );
>>
>> insert into FOO(key) values ('[2014]');
>> insert into FOO(key) values ('[2015]');
>> insert into FOO(key) values ('[2016]');
>> insert into FOO(key) values ('[2014, 2]');
>> insert into FOO(key) values ('[2014, 2, 3]');
>> insert into FOO(key) values ('[2014, 3]');
>> insert into FOO(key) values ('[2014,2,4]');
>> insert into FOO(key) values ('[2014, 2,4]');
>> insert into FOO(key) values ('[2014,3,13]');
>> insert into FOO(key) values ('[2014, 2, 15]');
>>
>> And I try to sort these rows like that:
>>
>> SELECT key FROM FOO order by key;
>>
>> The result is:
>>
>> [2014]
>> [2015] <==
>> [2016] <==
>> [2014, 2]
>> [2014, 3] <==
>> [2014, 2, 3]
>> [2014, 2, 4]
>> [2014, 2, 4]
>> [2014, 2, 15]
>> [2014, 3, 13]
>>
>> But what I need is
>>
>> [2014]
>> [2014, 2]
>> [2014, 2, 3]
>> [2014, 2, 4]
>> [2014, 2, 4]
>> [2014, 2, 15]
>> [2014, 3] <==
>> [2014, 3, 13]
>> [2015] <==
>> [2016] <==
>>
>> is there a way to achieve it?
>>
>
> ​Maybe try:
>
> ORDER BY key->>1::int​, key->>2::int, key->>3::int
>
> There is no easy way, presently, to convert from a json array to a
> PostgreSQL array. If you do that I believe that those sort based upon the
> values and not lexically.
>
> SELECT *
> FROM ( VALUES (ARRAY[2014]::int[], ARRAY[2014,2]::int[],
> ARRAY[2015]::int[]) ) vals (v)
> ORDER BY v;
>
> David J.
>
> I spent a couple minutes goofing off on this question - this isn't exactly
right and is UGLY, but maybe helps a bit with some ideas (the virtual table
is needless, but my sql is rusty):

SELECT key, to_number(key#>>'{0}','9999') as order1,
to_number(key#>>'{1}','9') as order2 FROM FOO
order by order1, order2

"[2014, 2, 4]";2014;2
"[2014, 2, 15]";2014;2
"[2014, 2, 4]";2014;2
"[2014, 2]";2014;2
"[2014, 2, 3]";2014;2
"[2014, 3]";2014;3
"[2014, 3, 13]";2014;3
"[2014]";2014;
"[2015]";2015;
"[2016]";2016;

2014 is coming after all the elements that have a value associated with
2014 - probably you could solve this with a coalesce, but I'm out of time
messing with it. I hope it's helpful!

Steve