This guaranteed uniqueness comes at the cost of anonymity. In that case, the chance of collision changes from impossible to very very small because of the random bits. This means you are guaranteed to get a completely unique ID, unless you generate it from the same computer, and at the exact same time. In addition to this, it also introduces another random component just to be sure of its uniqueness. UUID v1 is generated by using a combination the host computers MAC address and the current date and time. We’ll talk about v5 later V1 : Uniqueness # UUIDs are just 128 bit pieces of data, that is displayed as (128/4) = 32 hexadecimal digits, like this : ba6eb330-4f7f-11eb-a2fb-67c34e9ac07cĪt first glance UUID v1 and v4 look the same, but try regenerating them and the difference will be more apparent. This is a tradeoff between uniqueness and randomness, and something that the different UUID versions solve in different ways. How do you ensure that there is just one copy of the identifier you made, and no more? And even then, how do you make sure that there is no correlation between any two identifiers? However, ensuring uniqueness is a challenge in itself. UUIDs address the problem of generating a unique ID - either randomly, or using some data as a seed. The “Universally unique identifier”, or UUID, was designed to provide a consistent format for any unique ID we use for our data. Having a unique identifier is an important requirement in many applications today. We will go through their implementation and differences, and when you should use them. This post will describe UUID v1, v4, and v5, with examples.
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