Re: [HACKERS] replicator - Mailing list pgsql-hackers

On Mon, 3 Jan 2000, Philippe Marchesseault wrote:

> So it could become:
> 
> SQL --IPC--> node-replicator
>                            |   |   |
>       via TCP send statements to each node
>                       replicator (on local node)
>                            |
>          via libpq send data to
>         current (local) backend.
> 
> >  (not exist any master node, all nodes have connection to all nodes)
> 
> Exactly, if the replicator dies only the node dies, everything else keeps
> working.

Hi,
I a little explore replication conception on Oracle and Sybase (in manuals).
(Know anyone some interesting links or publication about it?)
Firstly, I sure, untimely is write replication to PgSQL now, if we
haven't exactly conception for it. It need more suggestion from more
developers. We need firstly answers for next qestion:
1/ How replication concept choose for PG?2/ How manage transaction for nodes? (and we need define any
replicationprotocol for this)3/ How involve replication in current PG transaction code?
 

My idea (dream:-) is replication that allow you use full read-write on all
nodes and replication which use current transaction method in PG - not is
difference between more backends on one host or more backend on more hosts
- it makes "global transaction consistency".

Now is transaction manage via ICP (one host), my dream is alike manage 
this transaction, but between more host via TCP. (And make optimalization 
for this - transfer commited data/commands only.)


Any suggestion?


-------------------
Note:
(transaction oriented replication)
Sybase - I. model (only one node is read-write) 
 primary SQL data (READ-WRITE)               | replication agent (transaction log monitoring)    | primary distribution
server(one or more repl. servers)        |               /  |  \               |            nodes (READ-ONLY)
   |        secondary dist. server                         /  |  \                      nodes (READ-ONLY)
 

      If primary SQL is read-write and the other nodes *read-only*       => system good work if connection is disable
(dataare save to         replication-log and if connection is available log is write   to node).   
 

Sybase - II. model (all nodes read-write)
            SQL data 1 --->--+                        NODE I.               |            |               ^            |
      |     replication agent 1 (transaction log monitoring)               V        |    |        V               |
  |        replication server 1               |    ^               V               |        replication server 2
               NODE II.               |         |               ^         +-<-->--- SQL data 2               |
         |                                    replcation agent 2 -<--
 



Sorry, I not sure if I re-draw previous picture total good..
                            Karel