Comparison of data consistency assurance methods between MySQL and TiDB

Comparison of data consistency guarantee methods between MySQL and TiDB

Introduction:
In the modern Internet era, the scale of big data is growing exponentially, and the demand for concurrent read and write operations of database management systems is increasing day by day. . Ensuring the data consistency of the database has become an important indicator of the database management system. This article will analyze and compare the data consistency guarantee methods of the traditional relational database management system MySQL and the recently emerged distributed database management system TiDB.

1. MySQL data consistency guarantee method
MySQL is a widely used relational database management system. It uses the ACID (atomicity, consistency, isolation, durability) model to ensure data consistency.

1. Atomicity:
   Atomicity means that the operations in the database are an indivisible whole, either all of them are executed successfully or none of them are executed. MySQL uses transactions to achieve atomicity. Transactions include a series of database operations, which must either all be executed successfully or all be rolled back.

The following is a sample code for a MySQL transaction:

BEGIN;
INSERT INTO table1 (column1, column2) VALUES (value1, value2);
UPDATE table2 SET column1 = value1 WHERE column2 = value2;
COMMIT;

2. Consistency:
   Consistency refers to the integrity and constraints of the data before and after the database transaction operation. be consistent. MySQL ensures data consistency by defining and using table foreign keys, primary keys, and unique constraints.

The following is a sample code for a MySQL table:

CREATE TABLE table_name (
column1 datatype constraint,
column2 datatype constraint,
...
);

3. Isolation:
   Isolation refers to the isolation between multiple concurrent transactions in the database. The data seen during the execution of each transaction should be Consistent. MySQL uses locks to achieve isolation and prevent data inconsistencies caused by concurrent operations by locking data rows.

The following is a sample code for MySQL transaction isolation level:

SET SESSION TRANSACTION ISOLATION LEVEL read_committed;

4. Persistence (Durability):
   Persistence means that once the transaction is submitted successfully, the modifications made to the data will be permanently saved in the database. Even if the system fails, the data should not be lost. MySQL achieves durability by persisting data to disk after a transaction commits.

2. TiDB’s data consistency guarantee method
TiDB is an open source distributed database management system that adopts a distributed storage and computing architecture to ensure high availability and horizontal expansion. and has data consistency guarantee methods similar to MySQL.

1. Atomicity:
   The atomicity of TiDB is similar to MySQL. Transactions are used to ensure that a series of database operations either all succeed or are all rolled back. TiDB uses the Raft consensus algorithm to achieve atomicity of distributed transactions.

The following is a sample code for a TiDB transaction:

BEGIN;
INSERT INTO table1 (column1, column2) VALUES (value1, value2);
UPDATE table2 SET column1 = value1 WHERE column2 = value2;
COMMIT;

2. Consistency:
   TiDB also ensures data consistency through foreign keys, primary keys and unique constraints of the table. Consistency, similar to MySQL.

The following is a sample code for a TiDB table:

CREATE TABLE table_name (
column1 datatype constraint,
column2 datatype constraint,
...
);

3. Isolation:
   TiDB has a transaction isolation level similar to MySQL, and uses the MVCC (Multiple Version Concurrency Control) mechanism to achieve isolation. Through data version management, TiDB can isolate concurrent transactions from each other to ensure data consistency.

The following is a sample code for TiDB transaction isolation level:

SET SESSION TRANSACTION ISOLATION LEVEL read_committed;

4. Durability:
   TiDB also achieves durability by persisting data to disk, ensuring that once the transaction is committed successfully, the data will not be lost.

Conclusion:
MySQL and TiDB, as relational database management systems, adopt similar methods to ensure data consistency. They all use transactions for atomicity and consistency, locks for isolation, and disk persistence for durability. At the same time, TiDB, as a distributed database management system, also uses the Raft consistency algorithm and MVCC mechanism to ensure data consistency and isolation. Regarding the guarantee of data consistency, both MySQL and TiDB have their own advantages and applicable scenarios. Choosing an appropriate database management system needs to be decided based on specific business needs.

References:

1. "MySQL Transaction Control". https://www.runoob.com/mysql/mysql-transaction.html
2. "TiDB Fast Getting Started". https://docs.pingcap.com/tidb/stable/getting-started-with-tidb

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