>>>HI,
>>>
>>>>
>>>>GUIDs are useful if users are not permanently connected. GUIDs are supposed to give unique values (based, in part, on the fact that each network card has a unique serial number). However, GUIDs are fairly long - 16 bytes.
>>>
>>>I prefer char type surrogated key. So, if I make it like an GUID in a char format, it will be 32 chars. I am worry that will affects performance in the long run....
>>
>>Of course it will affect performance. Why not use the 16-char GUID, and then have a function that converts to a readable form when you need it?
>>
>>Also, do you really need GUIDs? If all users are connected at the same time, a 4-byte Integer should also work. But you may still consider GUIDs if you plan to upsize your system later (to include disconnected users).
>
>Strictly speaking, I don't really need GUID, just as Sergey Berezniker has pointed out what a GUID key should be. In my case, I just need a non-sequential char type surrogated key, so I think I am cutting down the length, probably 8 to 12 chars since there are tables that I expect will grow huge in term of #records.

And why must it be of type Character? A type Integer uses only 4 bytes, but numbers can go all the way to 2e9 (2000 million). I don't see any advantage in using Character.