About Replication - Why is Read-only Slave Possible?

[Sandy]

The redis.io documents say that redis slave is read-only by default. I am curious why it's possible, because:

First, the master will send its commands(write) using also redis protocol. So the slave has to distinguish which commands are from the master and be read-only  just to clients?

Second, the slave might also be other slaves' master, so read-only possible...?

[Josiah Carlson]

It is easy to distinguish which is the master connection and which are
client connections (of any kind).

If a slave is a slave (even if it is also a master), and it is set as
read-only, then it will be read only from every client, except the
upstream master.

Regards,
- Josiah

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[Aaron Blohowiak]

Another way to think of it is that the slave is a *client* to the master, but a *server* to your app.  This means the connections are very different!

[fuyou]

this is logic.as  your application to Guarantee 

2012/7/29 Aaron Blohowiak <aaron.b...@gmail.com>

Another way to think of it is that the slave is a *client* to the master, but a *server* to your app.  This means the connections are very different!

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                                                                             fuyou001

Best Regards

         

[Josiah Carlson]

The same way you find out if data is updated on the master:
1. You check (pull)
2. You subscribe to a channel or channel pattern, and any writes also
publish to the channel (push)

Regards,
- Josiah

On Thu, Sep 6, 2012 at 1:36 AM, Santosh <mcompu...@gmail.com> wrote:
> When data is updated on the slave, how the clients would come to know that
> the data is updated on the slave. Is there a way to know that?

> https://groups.google.com/d/msg/redis-db/-/eHqWqE6RZmUJ.