Re: [DOCS] Window function docs
| От | David G. Johnston |
|---|---|
| Тема | Re: [DOCS] Window function docs |
| Дата | |
| Msg-id | CAKFQuwbaRiEZwi5qSVu8vx6xXW0VHCjgfTTSv-Vmd7nEPxwZLA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: [DOCS] Window function docs (Bruce Momjian <bruce@momjian.us>) |
| Ответы |
Re: [DOCS] Window function docs
|
| Список | pgsql-docs |
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).
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.
David J.
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