"Sandro Santilli" <strk(at)keybit(dot)net> writes:
> SELECT a, b, ST_RelateMatch(a,b) FROM
> ( SELECT '101202FFF' as a, 'TTTTTTFFF' as b) as f;
> Results in:
> ERROR: failed to find conversion function from unknown to text
Cast those unknown literals to text explicitly, ie
SELECT a, b, ST_RelateMatch(a,b) FROM
( SELECT '101202FFF'::text as a, 'TTTTTTFFF'::text as b) as f;
We don't support doing it the other way because retroactively deciding
at the top level that the sub-select's outputs should have been text
might change the semantics of the sub-select (consider cases involving
DISTINCT for example).
regards, tom lane