SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 3)
    Identifier name
    Identifier value
    Identifier type
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier system.settings
   Function equals (children 1)
    ExpressionList (children 2)
     Identifier name
     Literal \'async_insert\'
