SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 3)
    Identifier b
    Identifier a
    Function JSONLength (children 1)
     ExpressionList (children 3)
      Identifier grp_aggreg
      Literal UInt64_100
      Literal NULL
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier test_table
   Set
