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 <br...@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
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