Re: Query optimization

On 10.01.2014 17:33, Mark wrote:
> On Fri, 10 Jan 2014 14:44:46 GMT, "Ken" <ktsahl_at_yoohoo.com> wrote:

> The query is as simple as this:
>
> SELECT column FROM table WHERE x = 'a' AND y = 'b' AND z = 1;
>
> There is an index on x, y and z.

Do you mean "there is a covering index on (x, y, z)" or do you mean "there is an index on x, an index on y and an index on z"? If the latter, try the covering index with the most selective column first.

> Anyway my client has solved the problem by setting the statistics to
> NULL.
Other queries aren't hurt?

Cheers

        robert Received on Sat Jan 11 2014 - 11:55:54 CET