Try setting the variable lc_collate, either in an individual session using SET or (to change it for all session) in postgresql.conf.

Craig Ringer wrote:

CK Leung wrote:

I create a new database use UTF-8 and SQL_ASCII, same result found, how
can i fix this problem ?


If I recall correctly, the collation order is set at initdb time, and
isn't bound to the database encoding. If that's right, you'd need to
dump all your databases, re-initdb with the new collation settings, and
re-load your databases.

--
Craig Ringer