The following bug has been logged on the website:
Bug reference: 16207
Logged by: toha.bakanovsky
Email address: im-scooter(at)yandex(dot)ru
PostgreSQL version: 12.0
Operating system: Ubuntu 16.04.11 64-bit
Description:
Localization functions upper() and lower() does not work for text returned
by convert_from() for cyrillic symbols.
select upper(convert_from(convert_to('абв', 'utf8'), 'utf8')) =
upper('абв'); -- return false
select upper(convert_from('абв'::bytea, 'utf8')), upper('абв'); -- return
false
hexdecimal presentation of text is identical
select convert_to(convert_from('абв'::bytea, 'utf8'), 'utf8') =
convert_to('абв', 'utf-8'); -- returns true
SHOW lc_ctype; -- -- "en_US.UTF-8"
On Postgresql 10.0 it works fine.