"Mojtaba Faridzad" <mfaridzad@stripped> wrote:
> I'm learning MySQL and I got two question:
>
> 1) As I know, MySQL has a buffer to keep the last records which have been retreived.
> So if I run a query two times, the second time will be faster. How can I temporarly stop
> this service? because I want to run different queries and compare their speed and find the
> best solution for a problem.
>
> 2) A table has 2 fields, Active CHAR(1), and Company CHAR(40). Sometimes I want to
> search a company name and sometimes I want to search an active company. For faster
> searching, do I need to create two index like these:
> CREATE INDEX active ON customer (CONCAT(active, company));
> CREATE INDEX company ON customer (company);
>
> If I create just the first index, do I still have a fast searching on company name (
> without mentioning Active )? like this:
> SELECT * FROM customer WHERE company = 'my test company';
Nope. If you have index only on (active, company), it will not be used in the above query.
--
For technical support contracts, goto https://order.mysql.com/?ref=ensita
This email is sponsored by Ensita.net http://www.ensita.net/
__ ___ ___ ____ __
/ |/ /_ __/ __/ __ \/ / Victoria Reznichenko
/ /|_/ / // /\ \/ /_/ / /__ Victoria.Reznichenko@stripped
/_/ /_/\_, /___/\___\_\___/ MySQL AB / Ensita.net
<___/ www.mysql.com
