What datasize is suitable for storing an RFID column in SQL server?

Question

I'm new to the whole RFID arena.

I need to store an RFID pr asset in the database. No decision has yet been made on what system will feed that particular field (or fields?) so I just want to set aside some space right now.

Oracle has this whole "Identity" package that handles, amongst other things, the different versions and types of RFID, but I havn't seen anything for SQL server.

Perhaps I'm overcomplicating things, but I've searched wide but found no reference to how big such a tag is, or even if it is suitable for being stored in one field, or if you need multiple.

So, what columns should I have, and what should their sizes be? Would nvarchar(10) suffice? nvarchar(20)?

Answer 1

There is no fixed data size for RFID tags. In fact they can store from a few bytes to a few kilobytes. They can even be used to hack into an unprotected system by storing code within them. Thus you should treat any data that you receive from them with the same suspicion that you would do from elsewhere.

As for an identifier that is uniques then if you allocate on the basis of it being no larger than a UUID then you should be OK.

Answer 2

AFAIK the generation 1 RFID tags are generally 128 bits, where 96 bits are the unique ID and the rest is checksum. But I strongly suspect that newer generations are at least 256 bits and it will continue to grow. I'm by no means an expert, so you may want to wait for another answer:)

So I'd go with a char or varchar of sufficient size, which should be easy to scale later.

Answer 3

Unfortunately, the standards in the RFID world at the moment specify all sorts of useful things, but not the tag size (these standards tend to be industry-specific and the ability to track cows may not map that well to what you have planned).

My advice would be to allocate something to hold enough for test data (nvarchar(10) should be fine) and then size it properly when you choose an actual implementation, at which point the vendor will be able to give you that information.

Answer 4

There is no set size for RFID tags, but I believe as it currently stands (Jan 2011) 2KB is the maximum size in HF specification, this includes the tag ID, user data and data set by the manufacturer required for the tag to function. In the UHF specification, instead of unique IDs you have an EPC which is editable by a reader if the tag is unlocked, unlike unique IDs in HF which are set and locked by the manufacturer. End of the day, you need to read the data layout for the memory of the tag your using. Manufactures will provide the technical document you need that explains the memory addresses available, and thus the max size you need.