CreateQuery test_tolowcardinality_nullable (children 3)
 Identifier test_tolowcardinality_nullable
 Columns definition (children 1)
  ExpressionList (children 2)
   ColumnDeclaration id (children 1)
    DataType UInt32
   ColumnDeclaration str (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType String
 Storage definition (children 4)
  Function MergeTree (children 1)
   ExpressionList
  Function toLowCardinality (children 1)
   ExpressionList (children 1)
    Identifier str
  Identifier id
  Set
