SQL Server case insensitive collation

Question

What are the benefits/drawbacks of using a case insensitive collation in SQL Server (in terms of query performance)?

I have a database that is currently using a case-ins

Answer 1

If you change the collation on the database, you also have to change it on each column individually - they maintain the collation setting that was in force when their table was created.

create database CollTest COLLATE Latin1_General_CI_AI
go
use CollTest
go
create table T1 (
    ID int not null,
    Val1 varchar(50) not null
)
go
select name,collation_name from sys.columns where name='Val1'
go
alter database CollTest COLLATE Latin1_General_CS_AS
go
select name,collation_name from sys.columns where name='Val1'
go

Result:

name collation_name
---- --------------
Val1 Latin1_General_CI_AI

name collation_name
---- --------------
Val1 Latin1_General_CI_AI