Re: ORDER BY question

On Dec 8, 4:49 am, baoqi..._at_gmail.com wrote:
> The architecture group of our company has told us to avoid using ORDER
> BY in our queries. Their reasons are:
>
> - In 10G, order by is incredibly inconsistent. They had an example with
> only 2 rows of data that was extremely slow. Even if it looks like it
> works alright, it's not guaranteed to, and we can't predict when
> it'll fail. That instability is one of the main reasons against it.
>
> - ORDER BY a primary key, especially when the primary key is not used
> in the where clause, has the worst performance and is definitely to be
> avoided.
>
> Is this true?

No. It is most likely utter nonsense.
If it is true it has to do with inadequate pga_aggregate_target and/or sort_area_size settings and/or other methods to bring the server on it's knees (like increasing the SGA to 100 percent of RAM).

-- 
Sybrand Bakker
Senior Oracle DBA