How to design a database for User Defined Fields?

Question

My requirements are:

• Need to be able to dynamically add User-Defined fields of any data type
• Need to be able to query UDFs quickly
• Need to be

Answer 1

If you're using SQL Server, don't overlook the sqlvariant type. It's pretty fast and should do your job. Other databases might have something similar.

XML datatypes are not so good for performance reasons. If youre doing calculations on the server then you're constantly having to deserialize these.

Option 1 sounds bad and looks cruddy, but performance-wise can be your best bet. I have created tables with columns named Field00-Field99 before because you just can't beat the performance. You might need to consider your INSERT performance too, in which case this is also the one to go for. You can always create Views on this table if you want it to look neat!