Re: Window function docs

On Thu, Apr 6, 2017 at 06:43:38PM -0700, David G. Johnston wrote:
> On Thu, Apr 6, 2017 at 6:14 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
> On Thu, Apr  6, 2017 at 03:53:24PM -0700, David G. Johnston wrote:
>
> > hypothetical-set aggregates as being distinct from ordered-set aggregates
> yet
> > the tables and the docs here do.
>
> Do you have any suggested text for that?
>
>
> - ​The built-in ordered-set aggregate functions are listed in Table 9-53 and
> Table 9-54.
> + The built-in ordered-set aggregate functions are listed in Table 9-53 while
> the built-in hypothetical-set ones are in Table 9-54.
>
> That's a direct translation.  Reading some more, though, I think that:
>
> + The built-in within-group aggregate functions are listed in Table 9-53
> (ordered-set) and Table 9-54 (hypothetical-set).

I went with this, for simplicity:

The built-in within-group ordered-set aggregate functions
are listed in <xref linkend="functions-orderedset-table">
while the built-in within-group hypothetical-set ones are in <xref
linkend="functions-hypothetical-table">.

> So now we'd have:
>
> grouping-aggregates:
> normal aggregates (no suffix modifiers, though can embed ORDER BY in the
> aggregate function argument area)
>
> within-group aggregates (requires WITHIN GROUP suffix modifier)
> ordered-set aggregates -> given parameters determine a record value, possibly
> imputed (within the defined group)
> hypothetical-set aggregates -> given a (virtual) record determine a parameter
> (within the defined group)
>
> non-grouping aggregates:
> window aggregates (requires OVER suffix modifier)
>
> The CREATE AGGREGATE only names those three specific types in the notes
> section.

Yes, very complicated.

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

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