It appears that casting to a char() causes spaces to be stripped (ignored) from the string:
mls=# select length('123 '::char(8));
length
--------
3
(1 row)
mls=# select length('123 '::char(8)::varchar(8));
length
--------
3
(1 row)
but:
mls=# select length('123 '::varchar(8));
length
--------
6
(1 row)
I'm not sure about anyone else, but I would personaly consider that a bug? Should the length function return the correct length of a fixed length string, or the length of significant characters? What does the SQL standard say on this one? I googled it a bit, but didn't come up with much.
Alex Turner
NetEconomist
On 10/20/05, Marc G. Fournier <scrappy@postgresql.org> wrote: On Thu, 20 Oct 2005, Doug Quale wrote:
> "Guy Rouillier" <guyr@masergy.com> writes:
>
>> Doug Quale wrote:
>>>
>>> # select 'a'::char(8) = 'a '::char(8);
>>> ?column?
>>> ----------
>>> t
>>> (1 row)
>>>
>>> Trailing blanks aren't significant in fixed-length strings, so the
>>> question is whether Postgresql treats comparison of varchars right.
>>
>> This result is being misinterpreted.
>>
>> select length('a'::char(8)) ==> 1
>> select length('a '::char(8)) ==> 1
>>
>> So it isn't that the two different strings are comparing equal. The
>> process of casting them to char(8) is trimming the blanks, so by the
>> time they become fixed length strings, they are indeed equal.
>
> Huh??? What version of PG are you using? On 7.4.9 ,
>
>
> test=# select length('a'::char(8));
> length
> --------
> 8
> (1 row)
>
> test=# select length('a '::char(8));
> length
> --------
> 8
> (1 row)
>
> The truncation you describe would simply be wrong.
ams=# select length('a '::char(8));
length
--------
1
(1 row)
ams=# select version();
version
----------------------------------------------------------------------
PostgreSQL 8.0.2 on i386-portbld-freebsd4.11, compiled by GCC 2.95.4
(1 row)
ams=#
----
Marc G. Fournier Hub.Org Networking Services (http://www.hub.org)
Email: scrappy@hub.org Yahoo!: yscrappy ICQ: 7615664
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