Re: Bug in either collation docs or code

> IIRC this was an intentional decision, made on the grounds that we
> can't tell whether the function/operator actually cares about having
> a determinate collation or not, so we have to leave it to execution of
> that function/operator to complain or not.
>
>
In this case, why treat implicit and explicit collation conflicts
differently? A conflicting explicit collation will produce an error during
planning, whereas a conflicting implicit collation will not produce an
error until execution.

create table foo(a text COLLATE "es_ES");
create table bar(b text COLLATE "de_DE");
insert into foo values('a'), ('b'), ('c'), ('d');
insert into bar values('b'), ('c'), ('g'), ('h');

SELECT * FROM foo WHERE a > (SELECT b FROM bar LIMIT 1); -- error during
execution
EXPLAIN SELECT * FROM foo WHERE a > (SELECT b FROM bar LIMIT 1); -- but no
error during planning
EXPLAIN SELECT 'c' COLLATE "de_DE" > 'ç' COLLATE "es_ES"; -- error during
planning

It seems like this would not allow the function/operator to decide if it
cares about a determinate collation during execution, since it would
already have errored out during planning.

--
Melanie Plageman