Yes, you are right, when you define a primary key an index is created.

If you does the query in the same order, the primary's key index is used. By
example:
- username, title ---> uses the primary's key index
- title, start_date ---> don't use the primarys key index, because it
has not a "username" column
- title, start_date, username ---> don't use the primary's key index
because the column "username" is not the first column.

Greetings.

Walter.

On Sun, Sep 11, 2011 at 2:17 PM, firebirdsql <firebirdsql@...> wrote:

> **
>
>
> If I a tables primary key is (username, title, start_date)...I'm guessing
> it
> will create an index on (username, title, start_date).
>
> If I'm querying by username, start_date, will it still use the index OR do
> I
> need to add an extra index for username, start_date)?
>
>
>


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