UUID Version 7
UUID Version 7 is a modern addition to the UUID specification, designed to offer time-based ordering with improved precision and without the potential privacy concerns of MAC addresses found in Version 1. It incorporates a Unix timestamp with millisecond precision.
Unix Timestamp (Milliseconds)
The first 48 bits of a Version 7 UUID are the Unix timestamp in milliseconds since the epoch (1970-01-01 00:00:00 UTC).
Randomness
The remaining 80 bits are filled with cryptographically secure pseudo-random data. This ensures uniqueness even when generated within the same millisecond.
Version and Variant Bits
The version bits are set to '0111' (hexadecimal '7'), and the variant bits are set to '10' (RFC 4122).
The format of a UUID Version 7 is xxxxxxxx-xxxx-7xxx-xxxx-xxxxxxxxxxxx. The '7' in the third group of hexadecimal digits indicates that it's a Version 7 UUID.
Benefits
UUID Version 7 provides chronological ordering, which is beneficial for database indexing and logging. The inclusion of random bits ensures high uniqueness without relying on potentially identifying hardware addresses.