I have already this mail to PATCHES mailing list and nobody replied me !!!.,
Hope the hackers and the developers send their ideas.
Qustion: is this approach is suitable for solving the need for locale per column in PostgreSQL ?
There is a function I attached to this mail. this function is similar to nls_sort. this function is written by Karel Zak, I dont know if he had tried to submit this code or not.
In this distribution you will find file nls_string.c. It contains the definition of function nls_string(text, text) which takes a string parameter and a locale name and returns string describing the ordering. So you can run
select * from table order by nls_string(name, 'en_US.UTF-8')
or
select * from table order by nls_string(name, 'cs_CZ.UTF-8')
or
select * from table order by nls_string(name, 'C')