Re: unexpected (to me) sorting order

[Glyn Astill <glynastill@xxxxxxxxxxx>]

> From: Scott Marlowe <scott.marlowe@xxxxxxxxx>

> To: Glyn Astill <glynastill@xxxxxxxxxxx>
> Cc: Björn Lundin <b.f.lundin@xxxxxxxxx>; "pgsql-general@xxxxxxxxxxxxxx" <pgsql-general@xxxxxxxxxxxxxx>
> Sent: Thursday, 9 April 2015, 13:23
> Subject: Re: unexpected (to me) sorting order
>
> On Wed, Apr 8, 2015 at 3:33 AM, Glyn Astill <glynastill@xxxxxxxxxxx>
> wrote:
>
>>
>>> From: Björn Lundin <b.f.lundin@xxxxxxxxx>
>>> To: pgsql-general@xxxxxxxxxxxxxx
>>> Sent: Wednesday, 8 April 2015, 10:09
>>> Subject: [GENERAL] unexpected (to me) sorting order
>>>
>>> select * from T_SORT order by NAME ;
>>>
>>> rollback;
>>> id |        name
>>> ----+--------------------
>>>   1 | FINISH_110_150_1
>>>   2 | FINISH_110_200_1
>>>   3 | FINISH_1.10_20.0_3
>>>   4 | FINISH_1.10_20.0_4
>>>   5 | FINISH_1.10_30.0_3
>>>   6 | FINISH_1.10_30.0_4
>>>   7 | FINISH_120_150_1
>>>   8 | FINISH_120_200_1
>>> (8 rows)
>>>
>>> why is FINISH_1.10_20.0_3 between
>>> FINISH_110_200_1 and
>>> FINISH_120_150_1
>>> ?
>>>
>>> That is why is '.' between 1 and 2 as in 110/120 ?
>>>
>>>
>>> pg_admin III reports the database is created like
>>> CREATE DATABASE bnl
>>>   WITH OWNER = bnl
>>>       ENCODING = 'UTF8'
>>>       TABLESPACE = pg_default
>>>       LC_COLLATE = 'en_US.UTF-8'
>>>       LC_CTYPE = 'en_US.UTF-8'
>>>       CONNECTION LIMIT = -1;
>>>
>>>
>>
>>
>>
>> The collation of your "bnl" database is utf8, so the
> "." punctuation character is seen as a "variable element"
> and given a lower weighting in the sort to the rest of the characters. 
> That's just how the collate algorithm works in UTF8.
>
> utf8 is an encoding method, not a collation. The collation is en_US,
> encoded in utf8. You can use C collation with utf8 encoding just fine.
> So just replace UTF8 with en_US in your sentence and you've got it
> right.

>

Yes, thanks for the correction there, and we're talking about the wider unicode collate algorithm.