for sqlite, multiple union sub-queries are emitted grouped (parens) which sqlite can not handle

[bughit]

https://github.com/brianhempel/active_record_union/pull/4#issuecomment-198833562

using gem 'active_record_union', github: 'odedniv/active_record_union' with sqlite

Post.where(id: 1).union(Post.where(id: 2), Post.where(id: 3), Post.where(id: 4)).to_sql

produces

SELECT "posts".* FROM (
  (
    (
      SELECT "posts".* FROM "posts" WHERE "posts"."user_id" = 1
      UNION
      SELECT "posts".* FROM "posts" WHERE "posts"."id" = 2
    )
    UNION
    SELECT "posts".* FROM "posts" WHERE "posts"."id" = 3
  )
  UNION
  SELECT "posts".* FROM "posts" WHERE "posts"."id" = 4
) "posts"

[matthewd]

Per #523, Arel development is moving to rails/rails.

If this issue is still relevant, please consider reopening it over there. (Note that the Rails repository does not accept feature request issues, and requires reproduction steps that rely on Active Record's documented API.)

[kbrock]

Fix has been merged into Rails