Any one knows about MySQL Replication Relay for Peer-to-Peer Replication for Multi-master replications?

Please share if you know anything with example and syntax for multiple clients with as masters replications in MySQL.

closed as unclear what you're asking by McNets, Erik Darling, mustaccio, RDFozz, LowlyDBA Jan 11 '18 at 16:45

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  • What is your goal? – Rick James Jan 11 '18 at 8:36
  • i need to create one web app with multi master replication database connectivity. – kaushik Jan 11 '18 at 11:04
  • Still unclear -- Why multi-master? Will there be Slaves? You mentioned Relays, but that is not a necessary part of the system. Etc. – Rick James Jan 11 '18 at 14:32
  • a live slaves are also for masters of them slaves. e.g. server-A is a master and Server-B is a slave of Server-A but Server-B is also master of Server-C. – kaushik Jan 16 '18 at 6:51
  • "A -> B -> C" is not considered "multi-master". A is a Master, B is a Relay (acting both as a Master and a Slave), and C is a Slave. There are only a few useful cases for such; can you elaborate on what the goal is of the configuration? Perhaps from that, you could start a new Question. (Getting this question off Hold is hard.) – Rick James Jan 16 '18 at 12:54

(The question is much too broad. So, I will give only a broad explanation of Master, Slave, and Relay.)

A server can be a Master, a Slave, or both.

Dual-Master (a form of multi-master) has both servers being both Master and Slave. By having server_id different for the two servers, Replication is smart enough not to get into a loop.

In a multi-master setup, one can write to any Master. There are many caveats one needs to be aware of.

A "Relay" server acts as a Slave to receive data from a Master, then passes it on to Slave(s).

In a Master-Slave or Master-Relay-Slave setup, one should write only to the Master. Writing to a Relay or Slave is asking for trouble.

Clients can talk to any MySQL server; it does not matter whether they are Master or Slave or both. However, typically one controls which server to talk to -- in order to control load balancing, HA, etc.

Galera and InnoDB Cluster / Group Replication are tools to make Multi-Master configurations more manageable.

  • will you please send me steps for multi master replication creation and how to use? – kaushik Jan 11 '18 at 10:31
  • Do not use Multi-Master, it is fraught with issues of duplicate keys, hung replication, difficulties in recovery, etc. – Rick James Jan 11 '18 at 14:32

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