Single index or composite indexes?

[Charlie Siu]

Hi all,

I designed a table to handle generic form submition:

The field includes userid, formname, fieldname, fieldvalue. In userid, formname, fieldname, they are neither one is unique, but three of them joining together is unique.

The performance is critical to me as in each form, each field will occupy 1 record. so each person submitted a form may generally created around > 30 record.

which one do you think the performance is better? Or any suggestion to me to improve the performance? Thanks in advance!!!

Case 1
----------------
userid primary key
formname primary key
fieldname primary key
fieldvalue


Case 2
-----------------
id primary key
userid
formname
fieldname
fieldvalue