1. What is Snowflake algorithm
Snowflake algorithm is an algorithm for generating globally unique IDs, developed by Twitter. It can generate globally unique IDs in distributed systems and solve problems such as data merging and sharding in distributed systems.
The ID generated by the snowflake algorithm is a 64-bit long integer number, consisting of the following parts:
- ##1 bit: sign bit, always 0.
- 41 bits: timestamp, accurate to millisecond level, can be used for 69 years.
- 10 bits: working machine ID, can be deployed on 1024 nodes.
- 12 bits: sequence number, each node can generate up to 4096 IDs per millisecond.
The process of generating ID by Snowflake algorithm is very simple. First record a start time, and then calculate the time difference between the current time and the start time each time the ID is generated, and combine the timestamp with the working machine. The ID and serial number are combined into a 64-bit long integer number and returned to the caller.
Snowflake algorithm is an efficient and reliable globally unique ID generation algorithm, which has been widely used in distributed systems.
2. Advantages and Disadvantages of Snowflake Algorithm
Advantages:
- Globally Unique: The ID generated by Snowflake Algorithm is globally unique and can be used for distribution Data fragmentation and data merging in the system avoid the problem of ID conflicts.
- Time ordering: The ID generated by the Snowflake algorithm contains timestamp information. The generation time can be calculated based on the size of the ID, which facilitates data sorting and query.
- High performance: The Snowflake algorithm generates IDs very quickly and can meet the needs of high-concurrency scenarios.
- Scalability: The data structure of the snowflake algorithm is relatively simple and easy to expand and modify.
Disadvantages:
- Depends on the system clock: The snowflake algorithm relies on the system clock during ID generation. If the system clock is dialed back, This may cause duplicate IDs to be generated.
- Fixed length: The length of the ID generated by the snowflake algorithm is fixed at 64 bits, which may result in higher storage and transmission costs.
- Does not support distributed computing: The process of generating IDs by the Snowflake algorithm is single-threaded and cannot support distributed computing.
Snowflake algorithm is an efficient and reliable globally unique ID generation algorithm, but you need to pay attention to shortcomings such as clock back and fixed length. When choosing an ID generation algorithm, you need to comprehensively consider the application scenarios and requirements to select a suitable algorithm.
3. Use snowflake algorithm in spring boot project
1. Introduce snowflake algorithm dependency
<dependency>
<groupId>com.github.beyondfengyu</groupId>
<artifactId>snowflake-spring-boot-starter</artifactId>
<version>1.0.0</version>
</dependency>
2. Configure snowflake algorithm parameters in the configuration file
Configure the parameters of the Snowflake algorithm in application.yml or application.properties:
snowflake:
data-center-id: 1 # 数据中心ID，可以使用机器IP地址最后一段数字，范围为0-31
machine-id: 1 # 机器ID，可以使用服务器编号，范围为0-31
3. Inject the Snowflake algorithm object
In the class that needs to generate a unique ID, use the @Autowired annotation to inject SnowflakeIdWorker Object:
@Service
public class UserService {
@Autowired
private SnowflakeIdWorker snowflakeIdWorker;
public Long generateUserId() {
return snowflakeIdWorker.nextId();
}
}Use the snowflakeIdWorker.nextId() method to obtain the generated snowflake ID.
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