UUID Version 6
UUID Version 6 is a more recent addition to the UUID family, designed to improve time-based UUIDs for indexing in databases. It reorders the timestamp components of a Version 1 UUID to place the most significant parts of the timestamp first, resulting in better chronological ordering.
Reordered Timestamp
The 60-bit timestamp is constructed from the Unix epoch timestamp (seconds and microseconds) and is placed at the beginning of the UUID. The most significant bits are in the first 32 bits, followed by the next 16, and then the remaining 12.
Clock Sequence and Node Identifier
These components are the same 14-bit clock sequence and 48-bit node identifier as in UUID Version 1.
Version and Variant Bits
The version bits are set to '0110' (hexadecimal '6'), and the variant bits are set to '10' (RFC 4122).
The format of a UUID Version 6 is xxxxxxxx-xxxx-6xxx-xxxx-xxxxxxxxxxxx. The '6' in the third group of hexadecimal digits signifies that it's a Version 6 UUID.
Benefits for Indexing: By placing the timestamp at the beginning and in a more granular order, UUID Version 6 values are chronologically sortable, which can significantly improve database indexing performance, especially for time-series data.
Privacy Considerations
Similar to Version 1, Version 6 can potentially reveal the identity of the generating device through the node identifier (MAC address). Consider privacy implications in your application.