I read the recent post on Primary Key Best Practices. The general take away for me was that using a text field for the primary key will be slower than using a number field. Especially for a large number of records or use over a LAN. My understanding of Multi-keys is that they must be text fields so that they can hold a delimited list. Based on this, I was wondering when it would be a good practice to use Multi-key fields and would it not be good practice. Please advise?