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help / color / mirror / Atom feedFrom: Anthony Ananich <anton.ananich@gmail.com>
To: pgsql-sql@postgresql.org <pgsql-sql@postgresql.org>
Cc: David G. Johnston <david.g.johnston@gmail.com>
Cc: Steve Midgley <science@misuse.org>
Subject: Re: Custom sort order with jsonb key
Date: Thu, 23 Jun 2016 22:40:55 +0300
Message-ID: <DA35C915-50AB-4611-87D1-438BA68EF117@gmail.com> (raw)
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> On Jun 23, 2016, at 22:14, Steve Midgley <science@misuse.org> wrote:
>
>
>
> On Thu, Jun 23, 2016 at 12:03 PM, David G. Johnston <david.g.johnston@gmail.com <mailto:david.g.johnston@gmail.com>> wrote:
> On Thu, Jun 23, 2016 at 2:38 PM, Anton Ananich <anton.ananich@gmail.com <mailto:anton.ananich@gmail.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
>
>
In my case the array may be much longer and contain not just numbers, but also strings.
It may be easier to patch RDBMS sources. Where is this sort performed?
Regards,
Anthony Ananich
http://ananich.pro <http://ananich.pro/;
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To: pgsql-sql@postgresql.org
Cc: anton.ananich@gmail.com, david.g.johnston@gmail.com, science@misuse.org
Subject: Re: Custom sort order with jsonb key
In-Reply-To: <DA35C915-50AB-4611-87D1-438BA68EF117@gmail.com>
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