Hi,
Since user_id is a primary key. It should work either with any of the column
and with both the column.
Any suggestion.
Thanks
On Thu, May 15, 2008 at 1:22 AM, Rob Wultsch <wultsch@stripped> wrote:
> On Tue, May 13, 2008 at 1:30 AM, Krishna Chandra Prajapati
> <prajapatikc@stripped> wrote:
> > Hi all,
> >
> > Below is the user_delivery table structure.
> >
> > CREATE TABLE `user_delivery` (
> > `user_id` decimal(22,0) NOT NULL default '0',
> > `delivery_id` decimal(22,0) NOT NULL default '0',
> > `send_to_regulator` char(1) default NULL,
> > PRIMARY KEY (`user_id`),
> > KEY `user_delivery_comp1` (`user_id`,`delivery_id`),
> > CONSTRAINT `fk_user_delivery` FOREIGN KEY (`user_id`) REFERENCES
> > `user_info` (`user_id`) ON DELETE NO ACTION ON UPDATE NO ACTION
> > ) ENGINE=InnoDB DEFAULT CHARSET=latin1;
> >
> > According to me user_delivery_comp1 index can be dropped and new index
> can
> > be created on delivery_id column. I would to know that the changes will
> work
> > or not. Yours suggestion regarding this table structure.
> >
> > Thanks,
> > --
> > Krishna Chandra Prajapati
> >
>
> Define work.
>
> The effect should be something like:
> Queries that have where clauses for delivery_id but not user_id would
> be able to use an index.
> Queries that have where clauses for delivery_id and user_id might not
> be able to use as much of an index. Depending on your version of mysql
> merge index may apply, but I am not knowledge enough to comment of the
> performance differences between the two. I would assume a composite
> index when available would generally be more ideal.
>
>
> --
> Rob Wultsch
> wultsch@stripped
> wultsch (aim)
>
--
Krishna Chandra Prajapati
MySQL DBA,
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Email-id: prajapatikc@stripped
