David, Allen, Edward, thanks for the suggestions but I want to be able to sort theB records in the exact physical order in which they occured.B Using the port or pid numbers could potentially give me the wrong sequence should two events occur within the same millisecond (unless it is ruled out that this is not possible). Regards, Marco.
----- Original Message ---- From: Edward Brown <[EMAIL PROTECTED]> To: u2-users@listserver.u2ug.org Sent: Thursday, 24 April, 2008 1:07:13 PM Subject: RE: [U2] Guaranteed unique sequential keys Of course if the port number is added to the end of the key then you can still sort by date/time. In the past I've done an R%5 oconv on both the (internal) date and time before concatenation - this gives you a 10 digit number regardless of the date and time used, so no need for separators... Edward -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of David Murray Sent: 24 April 2008 11:53 To: u2-users@listserver.u2ug.org Subject: RE: [U2] Guaranteed unique sequential keys Marco, I have used similar processes in the past, but also have appended port number to the beginning of the key. Separating the fields with '*' so the date and time can also be used as a time stamp rather than duplicate the same info in the record. Cheers, David Murray *B B B B B B Learn and do *B B B Excel and share http://u2blog.org -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Marco Manyevere Sent: Thursday, April 24, 2008 5:55 AM 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. B B B __________________________________________________________ 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/ ----------------------------------------------------------------------------- -------------- Please remember to recycle wherever possible. Reduce, reuse, recycle, think do you need to print this e-mail? ----------------------------------------------------------------------------- -------------- This e-mail and any attachment(s), is confidential and may be legally privileged. It is intended solely for the addressee. If you are not the addressee, dissemination, copying or use of this e-mail or any of its content is prohibited and may be unlawful. If you are not the intended recipient please inform the sender immediately and destroy the e-mail, any attachment(s) and any copies. All liability for viruses is excluded to the fullest extent permitted by law. It is your responsibility to scan or otherwise check this email and any attachment(s). Unless otherwise stated (i) views expressed in this message are those of the individual sender (ii) no contract may be construed by this e-mail. Emails may be monitored and you are taken to consent to this monitoring.B Civica Services Limited, Company No. 02374268; Civica UK Limited, Company No. 01628868 Both companies are registered in England and Wales and each has its registered office at 2 Burston Road, Putney, London, SW15 6AR. ----------------------------------------------------------------------------- -------------- ------- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/ __________________________________________________________ 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/
