create table T
(
C1 varchar(10) not null,
C2 as C1+'1', --persisted,
index IX_T_C2 nonclustered (C2)
);
go
set ansi_warnings off;
select count(*)
from T with (index(IX_T_C2))
where C2 = ''
--option (querytraceon 176);
set ansi_warnings on;
select count(*)
from T
where C2 = '';
