"Guy Rouillier" <guyr@xxxxxxxxxxx> 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.
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
