Order By Clause, Slows Query Performance?

Eg. SELECT col1, col2, col3,....col10 FROM table1;

For above query If I didn't mention ORDER BY clause, then I want to know
selected data will appear in which order by a query planner?

Because I have huge size table, and when I applied ORDER BY col1, col2..in
query the
performance is soo bad that I can't offred.
What should I do ? Because my requirement is data with ordered column.



--
View this message in context:
http://postgresql.1045698.n5.nabble.com/Order-By-Clause-Slows-Query-Performance-tp5777633.html
Sent from the PostgreSQL - performance mailing list archive at Nabble.com.