Code:
dmitri=# CREATE TEMP TABLE q(i text);
CREATE TABLE
dmitri=# insert into q values('z');
INSERT 14116749 1
dmitri=# insert into q values('.z');
INSERT 14116750 1
dmitri=# insert into q values('.q');
INSERT 14116751 1
dmitri=# insert into q values('q');
INSERT 14116752 1
dmitri=# insert into q values('.');
INSERT 14116753 1
dmitri=# select * from q order by i;
 i
----
 .
 q
 .q
 z
 .z
(5 rows)
Why this going on?