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In addition to MySQL master-slave, you have another choice, Galera

Most Internet companies , All use MySQL Of InnoDB The engine stores data .

To ensure high availability of database , In order to ensure the expansion of performance , Most companies will use Master slave synchronization , Read / write separation Of MySQL Cluster architecture .

Traditional master-slave synchronization , Read / write separation MySQL The cluster architecture is shown in the figure above :

(1) Main library : The first instance on the left , Provide an instance of the write service ;

(2) Slave Library : Two instances on the right , Provide an instance of the read service ;

How does data replication work at this time ?

Still as shown in the figure above :

(1) The client submits the write operation to the main library ;

(2)Replication: The main library serializes the operation , adopt binlog To the slave library ;

(3) Perform the same sequence of operations from the library , For replica redundancy ;

Traditional master-slave synchronization , Read write separation redundancy mode , What are the problems with database clusters ?

(1) Users should pay attention to cluster details , Implement read-write separation ;

(2) Write library is still single point , Performance cannot be linearly scaled ;

(3) There is a delay in reading the library , Data inconsistency ;

(4) The writing library hung up , From the top of the library , There may be data loss ;

(5) If middleware is introduced ,SQL Ability will be affected ;

(6) O & M complexity ;

(7)…

Since there are so many pain points , Is there a technology , It can solve everyone's problems ?

Galera colony (Galera Cluster) Give birth to .

What is? Galera colony ?

Galera The cluster is based on MySQL InnoDB Synchronous replication :

(1) Sync ;

(2) Multimaster ;

(3) Database cluster ;

Voice over : It can support, for example MariaDB Wait for other databases , This article focuses on MySQL.

As shown in the figure above :

(1)Galera The cluster consists of a set of MySQL The cluster consists of ;

(2)Replication: This group MySQL Server usage Replication plug in To manage database replication ;

(3) The client can read and write to any node in the cluster ;

Galera The official website of the cluster is known as , It and its disadvantages :

(1) Real multi master (True Multi_Master), Any data changes will be copied to other nodes ;

(2) There is no such thing as slave latency (slave lag), Synchronous replication ;

(3) Strong consistency , All nodes are in a consistent state ;

(4) Hot standby , High availability , There is no need to deal with the so-called master-slave failover , There is no need to be empty IP;

(5) No read / write separation is required , You can read and write to any node at any time ;

(6) Support InnoDB;

(7) Transparent to the application ;

(8)…

 

All in all , In the description on the official website ,Galera Cluster is a highly available , High performance , To ensure data consistency and integrity :

(1) in the light of MySQL Of ;

(2) Based on synchronous authentication (synchronous certification-based);

(3) Multiple copies (replication);

Solution .

 

online Galera There seems to be less information , Asked some former friends , It doesn't seem to be used much in Internet companies , Ready to write in depth Galera colony , After all, MySQL Another choice after master-slave .

 

On the official website Galera, What technical points are you interested in ? Guess how it works ? Do you think it is necessary to write further ,or Change the subject ?

The comments told me .

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https://cdmana.com/2021/09/20210909130210377c.html

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