Question 1

What is NIL UUID?

Accepted Answer

NIL UUID (also called Null UUID) is a special UUID defined in RFC 4122 consisting entirely of zeros: 00000000-0000-0000-0000-000000000000. It represents an empty, uninitialized, or null UUID value. Unlike regular UUIDs which are unique, the NIL UUID is always the same value and serves as a standardized way to represent 'no UUID' or an empty state.

Question 2

When should I use NIL UUID?

Accepted Answer

Use NIL UUID for default values in database schemas, null checks in UUID comparisons, placeholder values during development, testing scenarios, and initialization of UUID variables. It's particularly useful when you need a valid UUID format but want to indicate an empty or unset state.

Question 3

Is NIL UUID the same as undefined or null?

Accepted Answer

No, NIL UUID is not the same as null or undefined. It's a valid UUID with a specific format (all zeros) that conforms to RFC 4122. While null/undefined means 'no value', NIL UUID is an actual value that explicitly represents emptiness. This is important in systems that require UUID format but need to indicate an empty state.

Question 4

Can I use NIL UUID in production?

Accepted Answer

Yes, NIL UUID is a standardized part of RFC 4122 and safe to use in production for its intended purposes: representing empty states, default values, and null references. However, never use it as an actual identifier for records, as it's not unique. It should only be used for special cases like empty states or validation checks.

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