Comparison of database replication and synchronization mechanisms between MySQL and TiDB

Comparison of database replication and synchronization mechanisms between MySQL and TiDB

With the advent of the big data era, the amount of data continues to grow, and the traditional database replication and synchronization mechanism is facing high concurrency and large data volume scenarios. The next one seems to be unable to do what he wants. In order to solve this problem, a new database system-TiDB has emerged, which is based on a distributed database architecture and can meet the storage and processing needs of massive data. This article will compare the database replication and synchronization mechanisms of MySQL and TiDB to discuss their advantages and disadvantages.

1. MySQL’s database replication and synchronization mechanism

MySQL’s database replication and synchronization mechanism is implemented through the binary log (binlog). It records all changes to the database into the binlog, and then The binlog is transferred to the standby database through the replication process, and the standby database updates data based on the contents of the binlog.

MySQL's database replication and synchronization mechanism has the following characteristics:

1. Master-slave mode: MySQL's replication mechanism is based on the master-slave mode. The master database is responsible for write operations, and The slave library is responsible for read operations.
2. One master and multiple slaves: MySQL's master database can have multiple slave databases, and chain replication can also be performed between slave databases to achieve higher scalability.
3. Asynchronous replication: MySQL replication is asynchronous, and the master library does not need to wait for confirmation from the slave library when passing the binlog to the slave library.

Although MySQL's database replication and synchronization mechanism performs well in some scenarios, there are also some problems:

1. Single point of failure: If the main database crashes, the entire The replication link will be interrupted and the slave database will no longer be able to replicate new data changes.
2. Data loss: Since MySQL replication is asynchronous, if the slave database lags too far behind the master database, data loss will occur.
3. Latency problem: Since replication is asynchronous, data changes in the slave database may be slower than those in the master database, resulting in inconsistent query results.

2. TiDB’s database replication and synchronization mechanism

TiDB’s database replication and synchronization mechanism is implemented based on the Raft protocol. Raft is a distributed consistency algorithm that can ensure Data consistency between multiple nodes. TiDB divides the database into multiple Regions, and each Region is composed of multiple copies, one of which is the Leader and the other copies are Followers.

TiDB’s database replication and synchronization mechanism has the following characteristics:

1. Multiple copy mechanism: Each Region of TiDB has multiple copies. When the Leader goes down, there will be A new Leader is elected from the Followers to ensure that data is not lost.
2. Data consistency: TiDB's database replication and synchronization mechanism is based on the Raft protocol, which can ensure data consistency between multiple nodes and avoid data inconsistency.
3. Transaction consistency: TiDB supports distributed transactions. It uses the two-phase commit (2PC) protocol to ensure transaction consistency and avoid data conflicts and concurrency issues.
4. High scalability: TiDB’s replication and synchronization mechanism supports dynamic expansion, and can increase or decrease the number of replicas according to needs to achieve high scalability.

3. Code examples

The following are code examples for replication and synchronization in MySQL and TiDB:

MySQL replication and synchronization code examples:

# 在主库上开启二进制日志
mysql> SET GLOBAL log_bin = ON;

# 创建复制账户
mysql> CREATE USER 'replication'@'slave_ip' IDENTIFIED BY 'password';
mysql> GRANT REPLICATION SLAVE ON *.* TO 'replication'@'slave_ip';

# 在备库上连接到主库
mysql> CHANGE MASTER TO MASTER_HOST = 'master_ip', MASTER_USER = 'replication', MASTER_PASSWORD = 'password';

# 开启复制进程
mysql> START SLAVE;

TiDB replication and synchronization code examples:

# 创建TiKV集群
pd-ctl> store add  :

# 创建数据库
mysql> CREATE DATABASE ;

# 创建表
mysql> CREATE TABLE  (
     ,
     ,
    ...
);

# 启用Replica读写
mysql> ALTER TABLE  SET TIFLASH REPLICA 3;

# 设置Region副本为3个
pd-ctl> region set  replicas 3;

Through the above code examples, we can see that TiDB replication and synchronization are more concise and flexible than MySQL, and have higher performance and reliability sex.

Conclusion

To sum up, MySQL’s database replication and synchronization mechanism is based on the master-slave mode of binary logs. Although it can meet the needs of some scenarios, there are single points of failure and data loss. and delays. TiDB's database replication and synchronization mechanism is based on the Raft protocol, which can ensure data consistency and transaction consistency, and has higher scalability and performance. Therefore, TiDB is a better choice when facing high concurrency and large data volume scenarios.

We hope that the comparison in this article can help readers better understand the database replication and synchronization mechanisms of MySQL and TiDB, and choose an appropriate database system based on actual needs.

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