Hi Marco - this is in fact the way I update files on very busy systems - we are getting say 30 hits per second and for logging with unique keys I have in the past used the date():system(12):endbit where endbit is incremented after doing a readvu to check if it exists or not. (as per your example), and system(12) is time in milleseconds
If you do not need to have absolute order then the @userno is a useful extra to the key and will give guaranteed uniqueness. Symeon. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Marco Manyevere Sent: 24 April 2008 10:55 To: u2-users@listserver.u2ug.org Subject: [U2] Guaranteed unique sequential keys What is the most reliable way to generate unique sequential keys without having to resort to a record on disk updated through readu/write? The keys don't have to be contiguous but only be sortable in the order in which they were generated by several phantom processes running concurrently. I'm currently approximating this using a concatenation of date and time with millisecondsB but I'm worried about the possibility of two phantoms generating exactly the same key. B Although no collision has been detected so far, I have added an extra check where after generating the key I first test if a record with that key exists. If so IB increment and append aB serial number and repeat the test until aB unique key is found. ItB seems to be working well but I still think there is a better way to do this. B Thanks for any help. B Marco. __________________________________________________________ Sent from Yahoo! Mail. A Smarter Email http://uk.docs.yahoo.com/nowyoucan.html ------- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/ ------- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/
