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About UUID v4

关于 UUID v4

UUID v4 uses 122 bits of randomness (6 bits are fixed for version and variant). The chance of a collision in 1 billion UUIDs is roughly 1 in 10⁻¹⁷. For almost all practical purposes, v4 UUIDs are unique. They are ideal for database primary keys, request IDs, and filenames where you do not want sequential enumeration.

UUID v4 使用 122 位随机数（其中 6 位固定用于版本和变体标识）。在生成 10 亿个 UUID 之后，冲突概率约为 10⁻¹⁷。实际应用中 v4 UUID 可以视为唯一。它们非常适合用作数据库主键、请求 ID 和不希望被顺序枚举的文件名。