Re: n00b question re: indexes and constraints
| От | David G. Johnston |
|---|---|
| Тема | Re: n00b question re: indexes and constraints |
| Дата | |
| Msg-id | CAKFQuwaf8TDx5D5e8Jjj0TLbSWL=GWMZFggPAe27X6AjW1u_2A@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: n00b question re: indexes and constraints (Wells Oliver <wells.oliver@gmail.com>) |
| Список | pgsql-admin |
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.oliver@gmail.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.g.johnston@gmail.com> wrote:On Wed, Apr 22, 2020 at 11:26 AM Wells Oliver <wells.oliver@gmail.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.oliver@gmail.com
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