List:General Discussion« Previous MessageNext Message »
From:Victoria Reznichenko Date:June 10 2003 9:19am
Subject:Re: Fw: 2 questions about indexing and testing speed
View as plain text  
"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
This email is sponsored by
   __  ___     ___ ____  __
  /  |/  /_ __/ __/ __ \/ /    Victoria Reznichenko
 / /|_/ / // /\ \/ /_/ / /__   Victoria.Reznichenko@stripped
/_/  /_/\_, /___/\___\_\___/   MySQL AB /

Fw: 2 questions about indexing and testing speedMojtaba Faridzad9 Jun
  • arrangement of fields in a tableMojtaba Faridzad9 Jun
    • Re: arrangement of fields in a tableJeremy Zawodny9 Jun
    • Re: arrangement of fields in a tableNils Valentin10 Jun
  • Re: Fw: 2 questions about indexing and testing speedVictoria Reznichenko10 Jun
Re: Fw: 2 questions about indexing and testing speedrich johnson10 Jun
  • INT typeMojtaba Faridzad10 Jun
    • Re: INT typeDan Nelson10 Jun
RE: INT typeMike Hillyer10 Jun
  • Re: INT typeMojtaba Faridzad10 Jun
    • Re: INT typePaul DuBois10 Jun
    • Re: INT typeDan Nelson10 Jun