ydb/yql/essentials/tests/s-expressions/suites/EquiJoin/ExtractRenameFromFlatMapOverJoin.yqls

(
(let mr_source (DataSource 'yt 'plato))
(let list1 (AsList 
  (AsStruct '('key1 (Int32 '1)) '('value1 (String 'A))) 
  (AsStruct '('key1 (Int32 '7)) '('value1 (String 'B)))
  (AsStruct '('key1 (Int32 '4)) '('value1 (String 'C)))
  (AsStruct '('key1 (Int32 '4)) '('value1 (String 'D)))
))

(let list2 (AsList 
  (AsStruct '('key2 (Int32 '9)) '('value2 (String 'Z))) 
  (AsStruct '('key2 (Int32 '4)) '('value2 (String 'Y))) 
  (AsStruct '('key2 (Int32 '3)) '('value2 (String 'X))) 
  (AsStruct '('key2 (Int32 '4)) '('value2 (String 'W)))
  (AsStruct '('key2 (Int32 '8)) '('value2 (String 'V)))
))

(let joinInner (EquiJoin '(list1 'a) '(list2 'b) '('Inner 'a 'b '('a 'key1) '('b 'key2) '()) '()))
(let list (Map joinInner (lambda '(x) (block '(
  (return (AsStruct
     '('"a.key1" (Member x '"a.key1"))
     '('"q" (Member x '"a.value1"))
     '('"f.value2" (Member x '"b.value2"))
  ))
)))))

(let res_sink (DataSink 'result))
(let world (Write! world res_sink (Key) list '('('type))))

(let joinInner2 (EquiJoin '(list1 'a) '(list2 'b) '('Inner 'a 'b '('a 'key1) '('b 'key2) '())
  '('('rename '"a.key1" 'z) '('rename '"b.key2" '""))))
(let list2 (Map joinInner2 (lambda '(x) (block '(
  (return (AsStruct
     '('"yy" (Member x '"z"))
     '('"q" (Member x '"b.value2"))
  ))
)))))

(let world (Write! world res_sink (Key) list2 '('('type))))
(let world (Commit! world res_sink))
(return world)
)