处理性能和使用数据类型

Question

I have some web forms that contain approx 100 to 150 text fields. So, in most of the fields a user can enter a great amount of string data. I had previously entered VARCHAR(150) , which will not be large enough.

So, my question is, which is better to use: VARCHAR(MAX) or TEXT ? I am using SQL Server 2008 R2.

There are many related questions available on Stack Overflow, but I am still confused. Assuming web forms with more than 50 fields with the TEXT datatype, will that cause any performance-related issues, or make our DB very large? I thought that VARCHAR(MAX) could store up to 8000 characters maximum, but I have some fields that can have more than 8000 characters.

Please guide...

Answer 1

If you're using SQL Server 2005 or newer use varchar(MAX). Text datatype is deprecated and should not be used for new development work.

see also: http://msdn.microsoft.com/en-us/library/ms187993%28v=sql.90%29.aspx

To answer your extra questions in the comments: 8000 is the maximum you can enter in a default varchar(x) type. This is because you can get maximum 8000 characters in a 'data-page'. But with varchar(max) you can store up to 2^31-1 bytes as @Doug_Ivison allready mentioned. Consequently as soon as the amount of characters is greater than 8000 you'll need multiple pages to contain your data. The same is valid for a 'text' type. It also will need multiple pages for this amount of data. So please don't use text. Besides the fact it's deprecated it doesn't support the things varchar(max) does, like ability to search & index.