On Fri, Aug 23, 2013 at 3:10 AM, Fabien COELHO <coe...@cri.ensmp.fr> wrote: > >> After someone in IRC asked if there was an equivalent to MySQL's >> server_id, it was noted that we do have a system identifier but it's not >> very accessible. >> >> The attached patch implements a pg_system_identifier() function that >> exposes it. > > > Would it make sense for such identifiers be standard UUID > (http://en.wikipedia.org/wiki/UUID)? > > Should there be a UUID per cluster? and/or per database, possibly deduce > from the cluster one? Should it be configurable, say from "postgresql.conf"? > > get_pg_uuid() > get_pg_uuid('template0') > > Note that there is a set of uuid functions provided as a module that may > help.
There is sense to this, sure. I'd think that constructing a Type 5 (SHA-1) UUID based on some local information would make a lot of sense. In effect, based on constructing SHA-1 on a string looking like: "Database system identifier: 5651554613500795646 Maximum data alignment: 8 Database block size: 8192 WAL block size: 8192 Maximum length of identifiers: 64 Date/time type storage: 64-bit integers Version: PostgreSQL 9.1.1 on x86_64-unknown-linux-gnu, compiled by gcc (Debian 4.6.1-4) 4.6.1, 64-bit" ==> SHA-1 of b1b012cc85149d2fe4bf0fc18c38dcf1218e95a5 (Note that I didn't put anything into that which is mutable such as port numbers, MAC addresses, or IP addresses - seems to introduce risk of false-negatives to me...) -- When confronted by a difficult problem, solve it by reducing it to the question, "How would the Lone Ranger handle this?" -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
