Обсуждение: Question about indexes

Поиск
Список
Период
Сортировка

Question about indexes

От
"Stefano Bonnin"
Дата:
Only a simple question
 
I have a table with
 
    primarykey(field1,field2,field3)
 
and I want to execure a query like
 
        select * from my_table where field1 = some_value
 
if I define an index on field1, I increase the query performace or not?
 
Thanks

Re: Question about indexes

От
Dawid Kuroczko
Дата:
On Mon, 15 Nov 2004 11:38:29 +0100, Stefano Bonnin
<stefano.bonnin@comai.to> wrote:
>
> Only a simple question
>
> I have a table with
>
>     primarykey(field1,field2,field3)
>
> and I want to execure a query like
>
>         select * from my_table where field1 = some_value
>
> if I define an index on field1, I increase the query performace or not?

You increase it a bit.  Anyway its not worth the hassle, as increase is
rather marginal, and having two indexes lessens the chance that
they'll be served from cache.

If you're not sure yet, just make some tests. :)

   Regards,
       Dawid