Weird "could not determine which collation to use for string comparison" with LEAST/GREATEST on PG11 procedure

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Weird "could not determine which collation to use for string comparison" with LEAST/GREATEST on PG11 procedure

Voillequin, Jean-Marc

Hello,

 

When I run the following script on a PG 11 psql:

 

select version();

show lc_collate;

create or replace function same_values_func(a text, b text) returns void as $body$

begin

                assert a = b;

end;$body$ language plpgsql;

select same_values_func(least('a','b'),'a');

create or replace procedure same_values_proc(a text, b text) as $body$

begin

                assert a = b;

end;$body$ language plpgsql;

call same_values_proc(least('a','b'),'a');

 

 

 

I get the following output and error at the end:

 

SIMPLE=> select version();

                                                version

--------------------------------------------------------------------------------------------------------

PostgreSQL 11.0 on x86_64-pc-mingw64, compiled by gcc.exe (Rev5, Built by MSYS2 project) 4.9.2, 64-bit

(1 row)

 

 

SIMPLE=>

SIMPLE=> show lc_collate;

lc_collate

------------

C

(1 row)

 

 

SIMPLE=>

SIMPLE=> create or replace function same_values_func(a text, b text) returns void as $body$

SIMPLE$> begin

SIMPLE$>        assert a = b;

SIMPLE$> end;$body$ language plpgsql;

CREATE FUNCTION

SIMPLE=>

SIMPLE=> select same_values_func(least('a','b'),'a');

same_values_func

------------------

 

(1 row)

 

 

SIMPLE=>

SIMPLE=> create or replace procedure same_values_proc(a text, b text) as $body$

SIMPLE$> begin

SIMPLE$>        assert a = b;

SIMPLE$> end;$body$ language plpgsql;

CREATE PROCEDURE

SIMPLE=>

SIMPLE=> call same_values_proc(least('a','b'),'a');

ERROR:  could not determine which collation to use for string comparison

HINT:  Use the COLLATE clause to set the collation explicitly.

SIMPLE=>

 

I tried to convert all void functions we have on a PG10 DB to procedures and I get this strange error.

The same error occurs with GREATEST.

Any idea?

Regards.

 

 

 

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Re: Weird "could not determine which collation to use for string comparison" with LEAST/GREATEST on PG11 procedure

Tom Lane-2
"Voillequin, Jean-Marc" <[hidden email]> writes:
> SIMPLE=> create or replace procedure same_values_proc(a text, b text) as $body$
> SIMPLE$> begin
> SIMPLE$>        assert a = b;
> SIMPLE$> end;$body$ language plpgsql;
> CREATE PROCEDURE
> SIMPLE=>
> SIMPLE=> call same_values_proc(least('a','b'),'a');
> ERROR:  could not determine which collation to use for string comparison
> HINT:  Use the COLLATE clause to set the collation explicitly.

Yeah, same here.  I think somebody forgot to run assign_expr_collations()
on CALL arguments.

                        regards, tom lane

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Re: Weird "could not determine which collation to use for string comparison" with LEAST/GREATEST on PG11 procedure

Tom Lane-2
Peter Eisentraut <[hidden email]> writes:
> On 21/11/2018 19:19, Tom Lane wrote:
>> Yeah, same here.  I think somebody forgot to run assign_expr_collations()
>> on CALL arguments.

> This appears to fix it.

I think this should be fine as a band-aid patch.  As I mentioned
previously, I'm not really happy with our generally-unprincipled
approach to where collation assignment is called from ... but a
bug-fix patch should probably not be tasked with making that
better.  Especially not with less than a week till 11.2.

                        regards, tom lane