CODEWITHSUNDEEP
uniqueidentifier
smaili
smaili

Reputation: 1235

How does StackOverflow/StackExchange generate unique integer IDs?

I'm looking for a way to generate unique integer IDs for my customers, very similar to how StackOverflow/StackExchange generates one for each question. The challenge is making this number unique in a distributed system since multiple databases are used, which means that the auto increment feature cannot work.

I have to assume that a huge site like StackOverflow/StackExchange is distributed, so I would very much like to know how it's able to generate a unique integer without any collisions.

From what I've seen, the two kinds of implementations around are Flickr's ticket server approach, but that creates a single point of failure, or Twitter's Snowflake, but that generates a 64 bit number, whereas StackOverflow's seems to be much smaller.

Upvotes: 0

Views: 79

Answers (1)

gnasher729
gnasher729

Reputation: 52602

Your operating system most likely has some way to do this. For example, on iOS or MacOS X you just call a method in NSUUID; others will have something similar. This gives you 122 random bits. If you insist on integers, I'd split this into two 64-bit integers. Uniqueness is practically guaranteed by having 122 random bits.

Upvotes: 0

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