On 6 September 2013 10:33, Richard Huxton <d...@archonet.com> wrote:
> On 06/09/13 09:13, Szymon Guz wrote:
>
>> Hi,
>> why isn't 'aa' always treated as string?
>>
>
> with x as (
>> select
>> '1' a,
>> '2' b
>> )
>> SELECT levenshtein(a, b), length(a)
>> FROM x;
>>
>> ERROR: failed to find conversion function from unknown to text
>>
>
> Why should I cast '1' to '1'::TEXT to satisfy a function (TEXT, TEXT)?
>>
>
> I think it's to do with the CTE. Presumably its types get fixed separately
> from the SELECT levenshtein() call. A quoted literal is type "unknown"
> until it has a context. It could be a date, point, hstore etc.
>
> If you use the literals directly the context lets PostgreSQL figure it out.
> SELECT levenshtein('1','2');
>
>
>
Yep, I can use literals without any problem, as this function is
levenshtein(text, text).
