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How to analyze MySQL Group Replication, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain for you in detail, people with this need can come to learn, I hope you can gain something.

Recently, I took a look at the content of MySQL Group Replication, because it hasn't been released for a long time, so it can be regarded as a new thing, and because of its unique meaning, this feature is even more meaningful.

I have been in contact with Oracle for a long time, so most of the time I like to look at it with a contrastive perspective. When I try to use this feature alone, I feel that I suddenly found the feeling when I was learning Oracle 10g RAC. There are still some minor problems, and there are still a lot of problems. I am eager to report errors, but the log is very limited. I can't find some relevant information. So sometimes I feel like an island of information.

I have read the information on the official website several times, and I have simulated it no less than 10 times in the computer environment, and each time I feel bad, and there are some places that people are not satisfied with. I think the effort in this aspect is really no less than that of Oracle, and I also know that it will take some time for this new feature to reach maturity and popularity. The process is always unforgettable and difficult.

First of all, this feature makes the volume of MySQL and Oracle closer. Look at the downloaded binary package, which makes people shake in their hands. The package is more than 600m, but it has almost 2.6G after decompression.

# du-sh. / *

2.6G. / mysql-5.7.17-linux-glibc2.5-x86_64

625M. / mysql-5.7.17-linux-glibc2.5-x86_64.tar.gz

If you look down carefully, you will find that the group replication part of it does take up a lot of space.

I think the following picture, if you want to see group replication, you have to say the last paragraph, which is naturally quoted in all kinds of blogs, originally from the interpretation of the official website.

From the native Replication to plug-in semi-synchronous, and then to Group Replication, is really a great progress, high availability solutions with the maturity of this technology will gradually become a trend, from Galera to the back of Percona packaging PXC, looking back from the Group replication point of view, unexpectedly found to be so similar. The authors of Galera are a group of veterans with more than 20 years of practical experience, and they are certainly not inferior to the official in terms of technological maturity. So choosing which or which is more mature will be a difficult choice for MySQL DBA.

And then another picture. Structure diagram of the MySQL plug-in.

This highly available solution of MySQL is a share nothing architecture, which makes the whole architecture a highly consistent design approach, which naturally uses multicast.

Building RAC in Oracle requires a cluster software. In the early days, it was an optional third party, and later it was unified for Oracle, that is, Grid Infrastrue, which is later called Grid Infrastrue. Not only the integration of cluster software, but also the part of ASM has been integrated, which feels like a forced demolition. At present, the mode of MGR is recommended in the form of single master, that is, the separation of read and write, and can also be multi-owner.

This part of MySQL Group Replication is implemented by Corosync. The origin of corosync comes from an Openais project, which can realize the transmission function of HA heartbeat information. It is one of the many HA cluster software. In the early laboratory version of MGR, we also need to pay special attention to this part of the information. The special configuration and configuration make the cluster environment run steadily, and MGR also includes the interface to bind corosync. This interface is actually an implicit mapping from corosync to client API.

From this, I also see several good solutions.

Corosync+pacemaker+mysql+drbd implements the high availability of mysql, and an idealistic practice of building Group Replication is to configure gtid first, and then switch to group replication to make the process smoother.

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