>-----Original Message----- >From: vegiv...@gmail.com [mailto:vegiv...@gmail.com] On Behalf Of Johan De >Meersman >Sent: Friday, January 21, 2011 1:22 AM >To: Anthony Pace >Cc: Michael Dykman; mysql. >Subject: Re: best way to have a unique key > >I have to say, something similar was my first thought, too - you never >mention uuid in your original post. As already stated, uuid() should be a >Universal Unique IDentifier. It's afaik a random 128-bit number; given the >space to choose from it should be rather unique. I have to admit that I'm >not entirely confident about that myself, either, though: as Pratchett put >it, one-in-a-million chances tend to pop up nine times out of ten. > [JS] A UUID (what Microsoft calls a GUID) is based in part on the MAC address of the generating device. Since MAC addresses are supposed to be unique across the known universe, so should a UUID.
Regards, Jerry Schwartz Global Information Incorporated 195 Farmington Ave. Farmington, CT 06032 860.674.8796 / FAX: 860.674.8341 E-mail: je...@gii.co.jp Web site: www.the-infoshop.com >The code should have bits for handling duplicate primaries regardless of the >method used to generate it, tough, so there's no reason to not do it. Having >two subsequent UUID() calls generate pre-existing numbers seems to me to be >likely in the same way as having Bush return his dirty oil dollars to Irak. > >On Thu, Jan 20, 2011 at 8:10 PM, Anthony Pace ><anthony.p...@utoronto.ca>wrote: > >> Dude, come on. I know that all primary keys have to be unique; however, I >> was obviously referring to the use of uuid over auto incrementation. >> >> On 1/20/2011 1:36 PM, Michael Dykman wrote: >> >>> It is axiomatic in the relational model that a primary must be unique. >>> This is not a quirk put forth by your current employer. Neither >>> MySQL nor any other RDBMS will allow you to establish a primary key >>> that is not unique. >>> >>> - michael dykman >>> >>> On Thu, Jan 20, 2011 at 1:32 PM, Anthony Pace<anthony.p...@utoronto.ca> >>> wrote: >>> >>>> Due to certain reasons, the company I am doing business with has decided >>>> that the primary key, for an orders table, be a unique key; however, I >>>> don't >>>> like the possibility of it conflicting if moved to another machine. >>>> >>>> What are some pitfalls of using a unique key, that is generated by a >>>> server >>>> side script, rather than by mysql? >>>> What are the best ways to do this? >>>> >>>> Please keep in mind this variable will also be displayed on the >>>> customer's >>>> Receipt, but again, since it's random, it doesn't have to mean anything. >>>> >>>> -- >>>> MySQL General Mailing List >>>> For list archives: http://lists.mysql.com/mysql >>>> To unsubscribe: http://lists.mysql.com/mysql?unsub=mdyk...@gmail.com >>>> >>>> >>>> >>> >>> >> >> -- >> MySQL General Mailing List >> For list archives: http://lists.mysql.com/mysql >> To unsubscribe: http://lists.mysql.com/mysql?unsub=vegiv...@tuxera.be >> >> > > >-- >Bier met grenadyn >Is als mosterd by den wyn >Sy die't drinkt, is eene kwezel >Hy die't drinkt, is ras een ezel -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
