Re: group by default order

hkongogo_at_gmail.com wrote:
> given a table
>
> create table product
> (
> product_id integer primary key,
> category varchar2(100),
> sale_count integer
> )
>
> what would be the order of
>
> select category, sum(sale_count) from product group by category;
>
> seems the order in 8i and 9i are different
>

There are many ways for a DBMS to do grouping, only some of which will result in a complete order.
Imagine the table being range partitioned on sale_count. The DBMS can run local group by-s without ever getting a total order. Other options involve hashing..

Cheers
Serge

-- 
Serge Rielau
DB2 SQL Compiler Development
IBM Toronto Lab