Re: DESC index column

["Rob Wultsch" <wultsch@xxxxxxxxx>]

On Tue, May 20, 2008 at 11:20 AM, Bof <bof90@xxxxxxxxx> wrote:
> Hi all -
> Is there a good workaround for mysql's lack of 'DESC'
> functionality when creating an index?
>
> I'm looking at migrating an Oracle RAC database to
> mysql (InnoDB or Cluster - testing both at the
> moment), and the Oracle database uses a lot of
> multi-column indexes with some colums indexed in
> descending order.
>
> If I can't emulate the descending index colums somehow
> it's likely to seriously impact performance and
> possibly derail the prospect of migration - help!
>
> cheers
> Iain

I have not yet run into performance issues with indexes not being
stored ascending.

Running queries with ORDER BY indexed_field ASC appears to me to have
the same or near the same performance characteristics as ORDER BY
indexed_field DESC. What are the circumstances where this crops up as
an issue?

-- 
Rob Wultsch
wultsch@xxxxxxxxx
wultsch (aim)

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