Re: Range type adaptation implemented

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От Karsten Hilbert
Тема Re: Range type adaptation implemented
Дата
Msg-id 20120924094541.GA3823@hermes.hilbert.loc
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Ответ на Range type adaptation implemented  (Daniele Varrazzo <daniele.varrazzo@gmail.com>)
Ответы Re: Range type adaptation implemented  (Karsten Hilbert <Karsten.Hilbert@gmx.net>)
Re: Range type adaptation implemented  (Daniele Varrazzo <daniele.varrazzo@gmail.com>)
Список psycopg
On Mon, Sep 24, 2012 at 09:56:14AM +0100, Daniele Varrazzo wrote:

> The funniest surprise I've had during the development
> was an error creating the object TextRange('#', '$') in the database.
> It should be possible as
>
>     >>> ord('#'), ord('$')
>     (35, 36)
>
> but PG insisted that "range lower bound must be less than or equal to
> range upper bound". Well, turns out that:
>
>     postgres=# select ascii('#') < ascii('$'), '#' < '$';
>      ?column? | ?column?
>     ----------+----------
>      t        | f
>     (1 row)

This does not seem intuitive but is probably quite logical:

While

    ascii('#') < ascii('$')

eventually compares numerical values (35 and 36) the comparison

    '#' < '$'

operates on characters the sorting order (<) of which
depends on the lcoale in use.

Karsten
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