Complete Guide to UUID v7: The Future of Unique Identifiers
UUID v7 is the newest UUID version, standardized in RFC 9562 (published in 2024). It represents a significant evolution in how we generate unique identifiers, combining the best aspects of time-based and random UUIDs.
What Makes UUID v7 Special?
UUID v7 uses a Unix timestamp (milliseconds since epoch) in the first 48 bits, followed by version and variant bits, then random data. This structure means UUID v7s are naturally sortable by creation time while maintaining uniqueness guarantees.
Structure of UUID v7
The 128 bits are organized as: 48 bits for Unix timestamp (milliseconds), 4 bits for version (always 0111 for v7), 12 bits for random data, 2 bits for variant, and 62 bits for additional random data.
Database Performance Benefits
Because UUID v7s are time-ordered, they maintain excellent B-tree index locality. New records always append near each other rather than scattering across the index, dramatically reducing index fragmentation and improving write performance.
Implementation in Popular Languages
Most modern UUID libraries now support v7. In PHP, use ramsey/uuid. In JavaScript, use uuid package v9+. In Python, use uuid6 package. In Go, use google/uuid v1.4+.
Conclusion
UUID v7 is the recommended choice for new applications that need globally unique identifiers. It provides the perfect balance between uniqueness, sortability, and database performance.
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