drop table if exists test.nested_map; create table test.nested_map (d default today(), k UInt64, payload default rand(), SomeMap Nested(ID UInt32, Num Int64)) engine=SummingMergeTree(d, k, 8192); insert into test.nested_map (k, `SomeMap.ID`, `SomeMap.Num`) values (0,[1],[100]),(1,[1],[100]),(2,[1],[100]),(3,[1,2],[100,150]); insert into test.nested_map (k, `SomeMap.ID`, `SomeMap.Num`) values (0,[2],[150]),(1,[1],[150]),(2,[1,2],[150,150]),(3,[1],[-100]); optimize table test.nested_map; select `SomeMap.ID`, `SomeMap.Num` from test.nested_map; drop table test.nested_map;