memory out of exception while executing query

Dear All,

i have windows service which push data from one database to another, i have a query which is

select * from tab1; e.g

if its result goes beyond 15000 rows it will give exception of memory out of exception and i am using sqlcommand object and i have set command timeout to 0, but every time it throws the exception.

if i limit it to selective column i.e select cola from tab1 .. will it works?
coz i dont have a live enviornment.

Best Regards

Nisar