W dniu 14.09.2017 o 10:57, George Neuner pisze: > On Thu, 14 Sep 2017 09:45:59 +0200, Rafal Pietrak <rafal@xxxxxxxxx> > wrote: > >> Hello everybody, >> >> Can anybody help me find a way to implement an ID which: >> >> 1. guarantees being unique across multiple tables. >> >> 2. guarantees its uniqueness not only during INSERT, but also during the >> lifetime of the database/application (e.i. during future UPDATES). >> >> 3. guarantees persistence of value across database backup/restore/upgrade. Seeing the answers I feel, I should probably have added: 4. not necessarily guarantee "planetary wide" uniquness. Meaning: backup/restore should instantiate those ID dupplication on the second instance of the database. > > UUID is the obvious choice, but it does take a lot of space. I was hoping for something like a database-scoped "primary key" - which in particular does not need to be anything big.... provided the dataset is small. As far as I can tell, UUID is an ID, that is "simple/fast" to generate, and has "extremally low" probability of collisions. Instead I was looking for a "mechanizms/program-sql-idioms" which don't have to be particularly efficient, but once generated, no matter what, the uniqueness is asurred by the database. Including UPDATEs - e.i. assignment of a completly new ID for a particular ROW. But I understand I may quit searching - there is nothing "so simple". > > Something like this might do the job: > http://rob.conery.io/2014/05/28/a-better-id-generator-for-postgresql/ I'll have a look, but this is not quite the tool I'm looking for. > > > George > > > Thank you all for answers. -R -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
