SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 2)
    Function and (children 1)
     ExpressionList (children 2)
      Function greaterOrEquals (children 1)
       ExpressionList (children 2)
        Identifier total_bytes
        Literal UInt64_5000
      Function lessOrEquals (children 1)
       ExpressionList (children 2)
        Identifier total_bytes
        Literal UInt64_15000
    Identifier total_rows
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier system.tables
   Function and (children 1)
    ExpressionList (children 2)
     Function equals (children 1)
      ExpressionList (children 2)
       Identifier name
       Literal \'check_system_tables\'
     Function equals (children 1)
      ExpressionList (children 2)
       Identifier database
       Function currentDatabase (children 1)
        ExpressionList
