I can’t speak to any performance differences when using them as indexed key fields for searches … they likely have similar performance, but that’s just a guess.
But here’s one situation where UUID has an advantage. We historically used the Sequence Number (a longint) as the primary key, until we discovered a shortcoming: Merging data from multiple data files leads to duplicated primary keys. With a sequence number, unless you somehow modify it (modifying the automatically-generated Sequence Number with some sort of instance prefix for the datafile) you will run into situations where different datafiles will have the same sequence numbers for various records. That’s not a problem if those files will forever remain separate, but it requires a lot of re-sequencing of those tables and related tables if the files are ever merged or need to communicate with one another while referencing primary keys. With UUID, it is highly unlikely (nearly impossible) that two data files will generate the same UUID for any records; the chances are nearly 100% that all of the UUID’s will be unique, across every instance of your database. So, if you later set up some kind of inter-database communication referencing records by primary key, or have to merge data files, you’re much less likely to run into issues. __ Ron Rosell President StreamLMS > On Aug 4, 2017, at 1:27 AM, stardata.info via 4D_Tech <[email protected]> > wrote: > > Hi All, > > Someone can explain when is better use UUID and when Longint field in primary > key? > > Thanks > Ferdinando > ********************************************************************** > 4D Internet Users Group (4D iNUG) > FAQ: http://lists.4d.com/faqnug.html > Archive: http://lists.4d.com/archives.html > Options: http://lists.4d.com/mailman/options/4d_tech > Unsub: mailto:[email protected] > ********************************************************************** ********************************************************************** 4D Internet Users Group (4D iNUG) FAQ: http://lists.4d.com/faqnug.html Archive: http://lists.4d.com/archives.html Options: http://lists.4d.com/mailman/options/4d_tech Unsub: mailto:[email protected] **********************************************************************
