Universally Unique Identifiers (UUIDs) are 128-bit numbers used to uniquely identify information in computer systems. Various versions of UUIDs serve different purposes and use different algorithms to ensure uniqueness and order. This document provides an overview of UUID version 7 (UUIDv7) and compares it with other commonly used UUID versions.

UUIDv7: Time-Based UUID with a Random Component

Overview

UUID version 7 (UUIDv7) is a proposed standard that introduces a time-based UUID with a random component. The primary goal of UUIDv7 is to provide a time-sortable UUID format while still retaining a high degree of uniqueness and randomness.

Structure

  • Timestamp: 48 bits representing the current time in milliseconds since Unix epoch.
  • Random Component: 64 bits of random or pseudo-random data.
  • Variant and Version: 16 bits to indicate the UUID variant and version.

Uses

  • Time-Based Sorting: UUIDv7 allows for chronological sorting of UUIDs, which is useful in applications that require ordered entries based on creation time.
  • High Uniqueness: By combining a timestamp with random bits, UUIDv7 provides a high probability of uniqueness and minimizes collisions.
  • Database Indexing: Useful in database systems where ordered keys are beneficial for performance.

Comparison with Other UUID Versions

UUIDv1: Time-Based UUID

  • Structure: Combines a timestamp with a node identifier (usually a MAC address) and a sequence number.
  • Uses: Generating unique identifiers based on time and hardware address.
  • Limitations: Privacy concerns due to inclusion of MAC address; potential for collisions if the system clock is not properly synchronized.

UUIDv2: DCE Security UUID

  • Structure: Similar to UUIDv1 but includes a POSIX UID/GID and some bits reserved for security and domain information.
  • Uses: Mostly for security-related applications and some legacy systems.
  • Limitations: Less commonly used; primarily seen in specific legacy systems.

UUIDv3: Name-Based UUID (MD5 Hash)

  • Structure: Generated by hashing a namespace identifier and a name using MD5.
  • Uses: Creating UUIDs based on a namespace and name, ensuring deterministic results.
  • Limitations: Uses MD5, which is cryptographically broken and less secure.

UUIDv4: Random UUID

  • Structure: Generated using random or pseudo-random numbers.
  • Uses: Broadly used where high randomness and uniqueness are desired.
  • Limitations: No inherent time-based or sequential information.

UUIDv5: Name-Based UUID (SHA-1 Hash)

  • Structure: Similar to UUIDv3 but uses SHA-1 hashing algorithm instead of MD5.
  • Uses: Deterministic UUIDs based on a namespace and name with improved security over UUIDv3.
  • Limitations: SHA-1 is deprecated and considered less secure than newer hashing algorithms.

Summary

  • UUIDv1: Good for time-based uniqueness but has privacy and collision issues.
  • UUIDv2: Specialized use cases with security context but not widely adopted.
  • UUIDv3: Deterministic and based on MD5, which is less secure.
  • UUIDv4: Highly random and widely used; lacks time-based sorting.
  • UUIDv5: Improved security over UUIDv3 with SHA-1, though SHA-1 is no longer considered secure.
  • UUIDv7: Provides a time-sortable UUID with randomness, combining benefits of time-based and random UUIDs.

UUIDv7 offers a compelling alternative by blending chronological sorting with randomness, making it suitable for scenarios requiring both time-based ordering and uniqueness.

Lepilo Web Tools