‫So the first thing we're going to discuss is master back up replication, sometimes called master stand
‫by replication.
‫And the idea here is you have one leader digging a base node that accepts rights and except grill operations
‫such as create table or alternative database stuff that you change in the database, create a new database
‫right versus right, where you're inserting Neuros in a table or updating in your arrow or deleting
‫rows.
‫These are called DM's.
‫So you do all your rights in one master node and there will be a lot of read only stand by Oracle back
‫up nodes which will receive those rights from the master node.
‫So that's the idea.
‫You don't write to those notes yourself as a client.
‫You always write to the master and the master replicates the data to the standby notes the beautiful.
‫This is like it's very simple to implement because you don't have conflicts is as one node that takes
‫rights and that's at nobody else is going to to have rights as well.
‫Right in the same time.
‫So here's how it looks like.
‫So this is the red one is the master node and the green ones are the stand-by replica nodes.
‫And if I want to insert or update or even create a new table or even to create a database or do anything,
‫I always do it to the master of the red database instance and that the act of doing that will propagate
‫those right to the back and nodes because there is a TCP connection between the replica node and the
‫master node that is like full bidirectional ready with a specific database user as well.
‫And this is the same thing here.
‫So anything you do here, this master node will push it to the child nodes or they call stand by nodes.
‫And and so that's that's beautiful.
‫So you want to have questions like Hosain does.
‫Does the client have to wait for these changes to be pushed to the back end or does it immediately if
‫it's written to the master?
‫Can I just immediately get back at once?
‫It's written to the writer said, look, this is another kind of debate and discussion and people are
‫already doing PhDs.
‫And what is best this is called synchronous versus asynchronous one I'm going to talk about in the other
‫room.
‫So in master backup or application, the beauty of this, if you're doing a read, you can either do
‫a read against the master.
‫You're going to get the fresh Aldo's up to date data, but you can always read against the replicas
‫again, the standby data.
‫That's absolutely fine.
‫You can read against those, but you cannot try to those.
‫The beauty of this is like if this is in a region, a specific region in Asia and this is in a specific
‫region in Europe and this is in America, you can still do that.
‫Yeah, the propagation will take time.
‫But if you if you can take the hit on this consistency, the eventual consistency, and that's what
‫the model is.
‫Yes, relational database is half eventual consistency, not just no sequel.
‫This is a relational database model, yet it has eventual distances.
‫So those clients will see that that might see the updates a little bit later.
‫If you can live with that, that's fine.
‫If you don't, there are ways to solve those, obviously.
‫But that's the idea here.
‫So you can you can scale horizontally.
‫And that's a beautiful this.