char vs. varchar for an indexed column

table folder

    id varchar(30) primary key
    path varchar(500) null

the table represents a hierarchial folder structure, path is like in filesystem - the id's concatenated by "/"

f1

    f1.1

        f1.1.1
f2

id    name     path
1     f1            /1
2     f1.1         /1/2
3     f1.1.1      /1/2/3
4     f2            /4

so what is better for id: char(30) or varchar(30) and what is better for path, char or varchar

i think varchar, because the index is much smaller -> less i/o -> better performance

am i right? Received on Fri Feb 08 2002 - 07:07:55 CST