So the order of the columns matter in the where clause filter. Doesn't the optimizer automatically rearrange the filter columns etc?
--- In [email protected], W O <sistemas2000profesional@...> wrote: > > 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)? > > > > > > > > > [Non-text portions of this message have been removed] >
