[feature request] named window expressions?

[yitao-li]

Is there a way in dbplyr to generate SQL of the form

SELECT
  SUM(`col1`) OVER `wnd` AS `s1`,
  SUM(`col2`) OVER `wnd` AS `s2`,
  SUM(`col3`) OVER `wnd` AS `s3`
FROM `my_table`
  WINDOW `wnd` AS (PARTITION BY `col4` ORDER BY `col5`)

?

(i.e., avoid spelling out the same window-spec repeatedly within the same query, and refer to it by a name instead) ?

The benefit of having this is the generated query would be shorter and easier to debug (as it's immediately clear that the same window spec is applied to multiple aggregations).

[hadley]

Not currently, and I suspect it wouldn't be worth the effort to implement it because it involving somehow hoisting data about individual expressions up to the query level. Not impossible, but I'd need to spend a decent amount of time thinking about it, and investigating support for WINDOW across databases.