Re: [PROPOSAL] new diagnostic items for the dynamic sql

Hi

I tested the last patch, and I think I found unwanted behavior.

The value of PG_SQL_TEXT is not empty only when the error is related to the
parser stage. When the error is raised in the query evaluation stage, then
the value is empty.
I think this is too confusing. PL/pgSQL is a high level language, and the
behaviour should be consistent independent of internal implementation. I am
afraid this feature requires much more work.

postgres=# DO $$
DECLARE
err_sql_stmt TEXT;
err_sql_pos INT;
BEGIN
EXECUTE 'SELECT 1/0';
EXCEPTION
WHEN OTHERS THEN
GET STACKED DIAGNOSTICS
err_sql_stmt = PG_SQL_TEXT,
err_sql_pos = PG_ERROR_LOCATION;
RAISE NOTICE 'exception sql "%"', err_sql_stmt;
RAISE NOTICE 'exception sql position %', err_sql_pos;
END;
$$;
NOTICE: exception sql ""
NOTICE: exception sql position 0
DO

For this case, the empty result is not acceptable in this language. It is
too confusing. The implemented behaviour is well described in regress
tests, but I don't think it is user (developer) friendly. The location
field is not important, and can be 0 some times. But query text should be
not empty in all possible cases related to any query evaluation. I think
this can be a nice and useful feature, but the behavior should be
consistent.

Second, but minor, objection to this patch is zero formatting in a regress
test.

Regards

Pavel