Explain EXPLAIN (children 2)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 1)
     Identifier json.a
    TablesInSelectQuery (children 2)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier test
     TablesInSelectQueryElement (children 1)
      ArrayJoin (children 1)
       ExpressionList (children 1)
        Identifier json.b
    Function and (children 1)
     ExpressionList (children 2)
      Function has (children 1)
       ExpressionList (children 2)
        Identifier json.a
        Literal UInt64_2
      Function less (children 1)
       ExpressionList (children 2)
        Identifier json.c
        Literal UInt64_5
