Re: disused indexes and performance?

On Wed, Oct 19, 2011 at 9:24 AM, Elisa <elisa(dot)derickson(at)shoutlet(dot)com> wrote:
> I recently ran a query against our production database and saw several
> disused indexes.  Is there a performance harm in having disused
> indexes out there?

Sure there is, they'll slow down writes and use more disk space.

> Of course, I will be checking our code base and with developers to
> ensure that these indexes aren't being used programmatically to
> prevent redundant inserts and the like. ..

Unique indexes are usually a small set compared to extra non-unique
indexes. Also, some indexes may be seldomly used by make a very big
difference on the rare occasion they are used, for instance partial or
functional or full test indexes.