Has anyone ever had a UUID collision?

Has anyone ever had a UUID collision?

It’s extremely unlikely there have been any collisions for properly generated UUID’s so far. (But buggy code has certainly generated collisions. )

Should I worry about UUID collisions?

You should certainly detect if a collision occurs, and your application should throw an exception if it does happen. E.g. if the UUID is used as primary key in the database, then the database should throw an error when inserting a colliding ID.

Is it possible for UUID to repeat?

Thus if n ≫ r, it is almost certain that there will be no duplicates. But if r does approach n, a UUID might repeat. A sample of 3.26*10¹⁶ UUIDs has a 99.99\% chance of not having any duplicates. Generating that many UUIDs, at a rate of one per second, would take a billion years.

Can two UUIDs be the same?

It may not be likely that any two UUIDs will be the same, but they can be. In this case, the code assigning UUIDs to devices may check a new UUID against any existing UUIDs already assigned to devices and throw away duplicates, guaranteeing uniqueness that way.

Is UUID collision likely?

A collision is possible but the total number of unique keys generated is so large that the possibility of a collision is almost zero. As per Wikipedia, the number of UUIDs generated to have atleast 1 collision is 2.71 quintillion. This is equivalent to generating around 1 billion UUIDs per second for about 85 years.

Can SHA256 collide?

The probability of just two hashes accidentally colliding is approximately: 1.47*10-29. SHA256: The slowest, usually 60\% slower than md5, and the longest generated hash (32 bytes). The probability of just two hashes accidentally colliding is approximately: 4.3*10-60.

How likely is a UUID collision?

Can 2 devices have the same UUID?

No, UUID’s should be unique among clients (or users) and should not be re-used.

Is UUID really globally unique?

A universally unique identifier (UUID) is a 128-bit label used for information in computer systems. The term globally unique identifier (GUID) is also used, often in software created by Microsoft. When generated according to the standard methods, UUIDs are, for practical purposes, unique.

Can you UUID v4 duplicate?

While the probability that a UUID will be duplicated is not zero, it is close enough to zero to be negligible. Thus, anyone can create a UUID and use it to identify something with near certainty that the identifier does not duplicate one that has already been, or will be, created to identify something else.

What is UUID in Python?

UUID, Universal Unique Identifier, is a python library which helps in generating random objects of 128 bits as ids. It provides the uniqueness as it generates ids on the basis of time, Computer hardware (MAC etc.).

Is SHA256 collision free?

The best one could do would be a brute-force birthday attack on this function, which would require on average 40³⁸ hashes. Since executing a brute-force attack of this size is considered computationally infeasible, SHA-256 can be considered collision-resistant, for now at least.

How many UUIDs does it take to generate a collision?

Amount of UUIDs that may be generated. A “random” UUID has 122 random bits. Assuming perfect randomness, you can expect the first collision at around 2^61 generated UUIDs (that’s the square root of 2^122).

How many UUIDs are generated in a year?

A “random” UUID has 122 random bits. Assuming perfect randomness, you can expect the first collision at around 2^61 generated UUIDs (that’s the square root of 2^122). If everyone on this earth were to generate a UUID per second, that’s 10,000,000,000*365*24*60*60 = 315360000000000000 UUIDs per year, which is quite close to 2^58.

What is the chance of two random UUIDs colliding with each other?

Assuming that the RNG is properly seeded the chance of a collision is quite low. UUIDs have 122 bits of entropy so the chance of two random UUIDs colliding is about 10^-37. If you generate 2^46 UUIDs (approximately 1 petabyte of entropy) the chance of getting a collision is 1 in 50 billion. [1]

Are GUID collisions possible?

Down vote because, in principle (in it’s rawest form), you are wrong saying “no” to the question “Are GUID collisions possible?”. It’s very possible. The likelihood of which is tiny, but it’s possible. I hate to sound pedantic – but SO is all about being concise and accurate.