Re: Failed to autoconvert '1' to text. - Mailing list pgsql-general

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');

--
   Richard Huxton
   Archonet Ltd