Re: n00b question re: indexes and constraints

For a single column unique definitely. For a multi-column separate indexes
to get subsets or different column order might be worthwhile.

David J.

On Wed, Apr 22, 2020 at 11:40 AM Wells Oliver <wells(dot)oliver(at)gmail(dot)com>
wrote:

> Thanks, I should have been more specific, these are unique constraints I
> am concerned about: so yeah, creating an index on a set of columns where
> there's a unique constraint is redundant, correct?
>
> On Wed, Apr 22, 2020 at 11:31 AM David G. Johnston <
> david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
>
>> On Wed, Apr 22, 2020 at 11:26 AM Wells Oliver <wells(dot)oliver(at)gmail(dot)com>
>> wrote:
>>
>>> Are constraints also indexes, or would you want an additional index on
>>> top of a constraint if you wanted that column/combo indexed?
>>>
>>
>> No, having a constraint does not imply that an index exists. However,
>> the enforcement of a "unique" constraint is implemented by auto-creating a
>> unique index.
>>
>> David J.
>>
>>
>
> --
> Wells Oliver
> wells(dot)oliver(at)gmail(dot)com <wellsoliver(at)gmail(dot)com>
>