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I have issue with generating global unique request id based on HttpServletRequest. I need to make sure the generated id is unique in Application scope. Java UUID Or Random does not guarantee what I want although the chance for duplicate is very low.

Anyone has any ideas? Thanks,

LHA
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2 Answers2

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If you have to be absolutely sure you don`t make a duplicate you could use an auto increment database id, but given the incredibly low chances of duplicates using UUID i dont think it justifies the cost.

Camilo Diaz
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  • Thanks. I think we can use combination of db sequence and random since I want the id is secured. – LHA Nov 22 '13 at 15:59
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Random definitely doesn't guarantee uniqueness, but UUID definitely does that. So your concern makes no sense. Even if you've hardware capable of serving a billion HTTP requests per second, you'd only after 100 years reach 50% chance on a duplicate.

If you have really really a hard head in this, just check in synchronized block if the application scope contains already such a key and if so, then just generate another one. And so on. This way you can even use Random.

See also:

Community
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BalusC
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  • Thank you for your answer. I will go with Random and checking the ID (Key) if it existing. – LHA Nov 22 '13 at 16:13