On 2014-06-23 10:09:49 -0400, Robert Haas wrote: > On Wed, Jun 18, 2014 at 12:46 PM, Andres Freund <and...@2ndquadrant.com> > wrote: > > On 2014-06-18 12:36:13 -0400, Robert Haas wrote: > >> > I actually don't think any of the discussions I was involved in had the > >> > externally visible version of replication identifiers limited to 16bits? > >> > If you are referring to my patch, 16bits was just the width of the > >> > *internal* name that should basically never be looked at. User visible > >> > replication identifiers are always identified by an arbitrary string - > >> > whose format is determined by the user of the replication identifier > >> > facility. *BDR* currently stores the system identifer, the database id > >> > and a name in there - but that's nothing core needs to concern itself > >> > with. > >> > >> I don't think you're going to be able to avoid users needing to know > >> about those IDs. The configuration table is going to have to be the > >> same on all nodes, and how are you going to get that set up without > >> those IDs being user-visible? > > > > Why? Users and other systems only ever see the external ID. Everything > > leaving the system is converted to the external form. The short id > > basically is only used in shared memory and in wal records. For both > > using longer strings would be problematic. > > > > In the patch I have the user can actually see them as they're stored in > > pg_replication_identifier, but there should never be a need for that. > > Hmm, so there's no requirement that the short IDs are consistent > across different clusters that are replication to each other?
Nope. That seemed to be a hard requirement in the earlier discussions we had (~2 years ago). > If > that's the case, that might address my concern, but I'd probably want > to go back through the latest patch and think about it a bit more. I'll send out a new version after I'm finished with the newest atomic ops patch. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
