| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | tuomas(dot)leikola(at)gmail(dot)com, pgsql-docs(at)lists(dot)postgresql(dot)org |
| Subject: | Re: uniqueness and null could benefit from a hint for dba |
| Date: | 2019-09-27 16:37:47 |
| Message-ID: | 20190927163747.GE31412@momjian.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-docs |
On Wed, Sep 4, 2019 at 01:12:35PM +0000, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
>
> Page: https://www.postgresql.org/docs/11/indexes-unique.html
> Description:
>
> Sometimes it is convenient to create an unique index that considers NULL
> values equal. Designating a "zero" value for those rows might not be
> feasible, for example due to a foreign key.
>
> The documentation currently only states that unique indexes do not consider
> NULLs equal. It might be good to offer workarounds, like indexing a coalesce
> function, if scans are not the reason for the index, but the uniqueness
> constraint.
I did write a blog entry about this:
https://momjian.us/main/blogs/pgblog/2017.html#April_3_2017
Does that help?
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Bruce Momjian | 2019-09-27 17:13:32 | Re: Please add example |
| Previous Message | Bruce Momjian | 2019-09-27 16:33:01 | Re: Release notes on "reserved OIDs" |