Wed Sep 1 20:25:05 PDT 2004
- Previous message: [Slony1-general] Slony don't wont to replicate anything
- Next message: [Slony1-general] The Kinda Dead "store listen" AutoGen Project
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
I have been mulling over the notion of setting up the Slonik STORE LISTEN(ORIGIN=a, RECEIVER=b, PROVIDER=c) configuration. The "features" of this idea: This involves having a table (view?) containing the intended parentage for each node, that is, which nodes point to which parents. This would allow the following good things: - Can't drop a node that has children, probably with other possible data checks - Can calculate the full "listener matrix" within pl/pgsql instead of doing it in Perl (take a look at init_cluster.pl, subroutine generate_listen_paths()). My preliminary thinking about it was pointing to there being a pretty elegant way to do this using SQL queries that might be more readable than the dynamic programming formulation embedded in that subroutine. (I didn't write out the Bellman equations, but took a look back at my old optimization texts ;-).) The primary problem that this solves is to create those STORE LISTEN() definitions, which get pretty involved to generate by hand if you get more than three nodes. In doing some further thinking, I noticed a couple of conspicuous challenges: 1. There can be no fixed association with sets, as the sl_listen table does not contain set fields, and different sets can use differently shaped subscription trees. (I think users would be doing something pretty stupid to have _wildly_ different arrangements for different sets, but I still have to support it...) 2. The tree cannot be based on subscriptions because it needs to exist before any subscriptions are established In effect, I have no fixed place where I can get the information at the point at which I most need it. Once all nodes are subscribed, I could use subscription information to weight the cost functions, but I need the data BEFORE we do anything. I'm going to drop some notes into the ToDo file, and leave it for now. - Maybe a better "seeding" idea will emerge later. - An idle thought: Maybe we do some manifest "defaulting." - In the beginning, all listens go to node #1 - Every time a subscription is established, the listeners get reevaluated based on what subscriptions exist. The idea's not dead; just dormant... -- (reverse (concatenate 'string "ofni.sailifa.ac" "@" "enworbbc")) <http://dev6.int.libertyrms.com/> Christopher Browne (416) 673-4124 (land)
- Previous message: [Slony1-general] Slony don't wont to replicate anything
- Next message: [Slony1-general] The Kinda Dead "store listen" AutoGen Project
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
More information about the Slony1-general mailing list