nvarchar compared to varchar - Any Performance Difference? 1

[JohnBates]

Hi experts,

I've read that the nvarchar (unicode) datatype performs more slowly than varchar.

But I can't make a valid argument to that without more information.

These people insist on leaving the datatype as nvarchar because that's the default when they upsize Access databases --> SQL Server 2000. They also love to overuse 'nullablility'.

Can anyone tell me how 1) nvarchar and 2)nullable columns
affect performance in general?

Thanks !
John

 

[nigelrivett]

Neither will have anywhere near as much affect as bad code. Anyone upsizing from access and not reviewing what happens (in fact relying on the upsize wiard) is unlikely to write efficient t-sql.

The most effect you will find is in wasted space - which is probably not a problem if you are upsizing an access system.
You may also find problems with products that don't support unicode.

Innapropriate use of nullability points to poor database design which will cause problems in maintaining integrity via the database structure.

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