char(xx) problem

Hi
we have two servers with installed Linux and PostGreSQL. They are quite
same. One is for development (Linux 2.2.9; 128 MB RAM; very overloaded with
processes), another for real HTTP serving in Internet (Linux 2.2.9; 64 MB
RAM; only http and pgsql)

In one of projects we had two tables:

create table a(
x char(2)
);

create table b(
y char(3)
);

When we try to execute SQL like this:

select * from a, b
where a.x = b.y;

one of servers selects 5-6 records (e.g. all mached records)
another selects empty table.

The database is one and same.

Why happen this?

PgSQL version 6.4, do i need to reinstall PgSQL, reinstall `db space' , or
how to fix it???

(I fix them with making chars with one and same length, and this is right
solution, but i want to have an idea why this difference exists)

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