Drop Down MenusCSS Drop Down MenuPure CSS Dropdown Menu

Adding a Cascaded Replication

In a standard Slony-I configuration all slaves(replicas) communicate directly with the master (origin). Sometimes it is more
desirable to have some of your slaves(replicas) feed off of another replica. This is called a cascaded replica and is supported by
Slony-I For example you might have a Slony-I cluster with 1 replication set (set id=1) and three nodes. The master (origin) for
set 1 (node id=1), a node in a different data center that reads directly from the master (node id=2) and a third node in the same
data center as the slave (node id=3). To the subscription sets in this configuration you need to make sure that paths exist between
nodes 2 and nodes 3. Then to perform the subscription you could use the following slonik commands.
#Setup path between node 1==>2
store path(server=1,client=2,conninfo=’host=masterhost,dbname=masterdb,user=slony,password=  -
store path(server=2,client=1,conninfo=’host=slave2host,dbname=slave2db,user=slony,password=  -
#Setup path between node 2==>3
store path(server=3,client=2,conninfo=’host=slave3host,dbname=slave3db,user=slony,password=  -
store path(server=2,client=3,conninfo=’host=slave2host,dbname=slave2db,user=slony,password=  -
subscribe set(set id=1, provider=1, receiver=2,forward=yes);
subscribe set (set id=1,provider=2, receiver=3,forward=yes);
wait for event(origin=1, confirmed=all, wait on=1);
In the above example we define paths from 1==>2 and from 2==>3 but do not define a path between nodes 1===>3. If a path
between node 1 and 3 was defined the data data for set 1 would still flow through node 2 because node 2 is the origin for set 1.
However if node 2 were to fail nodes 1 and 3 would be unable to talk to each other unless a path between nodes 1 and nodes 3
had been defined.
Slony-I requires that all sets from a given origin cascade to each receiver in the same manner. If node 1 was also the origin for
set 2 then set 2 would also need to go directly to node 2 and be cascaded from node 2 to node 3. Node 3 can not receive set 2
from node 1 directly if it is already receiving set 1 via node 2.


Popular posts from this blog

rman interview and scenario based questions and answer and also rman(backup and recovery) discussions panel

How to Get Table Size, Database Size, Indexes Size, schema Size, Tablespace Size, column Size in PostgreSQL Database

How to find the server is whether standby (slave) or primary(master) in Postgresql replication ?

7 Steps to configure BDR replication in postgresql

PostgreSQL pgBadger