Once you have learned how to replicate tables and add them to sets, it is time to learn about failover. Basically, we can distinguish between two types of failovers:
Planned failovers
Unplanned failovers and crashes
In this section, you will learn about both scenarios.
Having planned failovers might be more of a luxury scenario. In some cases, you will not be so lucky and you will have to rely on automatic failovers or face unplanned outages.
Basically, a planned failover can be seen as moving a set of tables to some other node. Once that node is in charge of those tables, you can handle things accordingly.
In our example, we want to move all tables from node 1 to node 2. In addition to this, we want to drop the first node. Here is the code required:
#!/bin/sh MASTERDB=db1 SLAVEDB=db2 HOST1=localhost HOST2=localhost DBUSER=hs slonik<<_EOF_ cluster name = first_cluster; node 1 admin conninfo = 'dbname=$MASTERDB host=$HOST1 user=$DBUSER'; node 2 admin...