> If you think that trailing spaces are significant data, you should > probably be using VARCHAR not CHAR datatype. I have existing database where there are only CHAR columns, no any VARCHAR column. I'm not sure will my appl work if I change all char columns to varchar columns . Is it reasonable to change all occurences of CHAR to VARCHAR in database ? Are the following clauses exactly same for fields of type CHAR(10): WHERE r1.c1::VARCHAR(10) || r1.c2::VARCHAR(10) || r1.c3::VARCHAR(10) >= r2.c1::VARCHAR(10) || r2.c2::VARCHAR(10) || r2.c3::VARCHAR(10) and WHERE r1.c1>=r2.c1 and r1.c2>=r2.c2 and r1.c3>=r2.c3 and WHERE (r1.c1, r1.c2,r1.c3) >= (r2.c1, r2.c2,r2.c3) Andrus.