On Thu, Apr 6, 2017 at 6:14 PM, Bruce Momjian <br...@momjian.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 <https://www.postgresql.org/docs/9.6/static/functions-aggregate.html#FUNCTIONS-ORDEREDSET-TABLE> while the built-in hypothetical-set ones are in Table 9-54 <https://www.postgresql.org/docs/9.6/static/functions-aggregate.html#FUNCTIONS-HYPOTHETICAL-TABLE> . 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.
