ydb/yql/essentials/tests/s-expressions/suites/ManyInputTables/BadUnionButUnusedFieldProject.yql

(
(let world (block '(
  (let x (Read! world (DataSource '"yt" '"plato") (Key '('table (String '"Input1"))) '('"key") '()))
  (let world (Left! x))
  (let table0 (Right! x))
  (let x (Read! world (DataSource '"yt" '"plato") (Key '('table (String '"Input2"))) '('"key") '()))
  (let world (Left! x))
  (let table1 (Right! x))
  (let output (block '(
    (let select (block '(
      (let core (block '(
        (let select (UnionAll (block '(
          (let core table0)
          (let core (FlatMap core (lambda '(row) (block '(
            (let res (Struct))
            (let res (AddMember res '"key" (Member row '"key")))
            (let res (AddMember res '"A" (String '"1")))
            (let res (AsList res))
            (return res)
          )))))
          (return core)
        )) (block '(
          (let core table1)
          (let core (FlatMap core (lambda '(row) (block '(
            (let res (Struct))
            (let res (AddMember res '"key" (Member row '"key")))
            (let res (AddMember res '"A" (Int64 '"1")))
            (let res (AsList res))
            (return res)
          )))))
          (return core)
        ))))
        (return select)
      )))
      (let core (FlatMap core (lambda '(row) (block '(
        (let res (Struct))
        (let res (AddMember res '"key" (Member row '"key")))
        (let res (AddMember res '"column1" ("Concat" (Member row '"key") (String '"AAA"))))
        (let res (AsList res))
        (return res)
      )))))
      (return core)
    )))
    (return select)
  )))
  (let world (block '(
    (let result_sink (DataSink 'result))
    (let world (Write! world result_sink (Key) output '('('type) '('autoref) '('columns '('"key" '"column1")))))
    (return (Commit! world result_sink))
  )))
  (return world)
)))
(let world (block '(
  (let plato_sink (DataSink '"yt" '"plato"))
  (let world (Commit! world plato_sink))
  (return world)
)))
(return world)
)