Re: pgsql: doc: add examples of creative use of unique expression indexes

On Fri, Apr 10, 2020 at 11:30:34AM -0400, Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > doc: add examples of creative use of unique expression indexes
> > https://git.postgresql.org/pg/commitdiff/a9760d0f3cb523336b5fdd9d6c5985e39a8588a1
>
> We had a complaint [1] that this dropped an example into the middle of
> two related paragraphs. I agree with that objection, and also notice
> that the extra example broke subsequent references to the "first example"
> and "second example". I'm also unhappy that the other addition that this
> commit made was dropped inside Example 11.3; if we're going to use
> <example> markup at all, each one ought to be a coherent entity.
>
> On top of that, I don't find that either example actually adds anything
> to the discussion, as the same points are being made in the existing
> text. Therefore, I don't think it's worth trying to fix these problems,
> and propose just reverting this patch.
>
> regards, tom lane
>
> [1] https://www.postgresql.org/message-id/158648685043.655.3074746555320970574%40wrigleys.postgresql.org

I agree with your analysis. I still want to have some mention that
partial indexes can be used to create single-NULL columns, which might
be required for compatibility with other databases. Attached is an
updated patch which removes the previous commit but adds a mention of
this.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EnterpriseDB https://enterprisedb.com

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