How to use Redis to achieve data persistence

How to use Redis to achieve data persistence

Introduction
Redis is a fast and efficient in-memory database, but by default its data is stored in in memory. This means that once the server is powered off or restarted, the data in Redis will be lost. In order to solve this problem, Redis provides some mechanisms to achieve data persistence. This article will introduce how to use Redis to achieve data persistence and give specific code examples.

1. RDB persistence
   RDB persistence is the default data persistence method of Redis. It achieves data persistence by dumping Redis data to a binary file (.rdb file) on the hard disk. You can trigger the save operation manually or set it to trigger the save automatically.

The following is a code example for manually triggering save:

SAVE

The following is a code example for setting automatic trigger save:

CONFIG SET save "60 1000"

The above code means that within 60 seconds, If 1000 keys have been modified, the SAVE command is automatically executed.

2. AOF persistence
   In addition to RDB persistence, Redis also provides AOF (Append-Only File) persistence. AOF persistence appends each write operation command to the Redis server to the end of a file (AOF file). When Redis restarts, the commands in the AOF file will be re-executed to restore the data.

The following is a code example to enable AOF persistence:

CONFIG SET appendonly yes

3. Hybrid persistence
   Redis also supports hybrid persistence, that is, using RDB persistence and AOF at the same time Persistence. This approach can take advantage of the advantages of both persistence methods while reducing their disadvantages.

The following is a code example to enable hybrid persistence:

CONFIG SET appendonly yes
CONFIG SET save "60 1000"

The above code enables AOF persistence and sets the RDB auto-save rule to 1000 keys modified within 60 seconds.

4. Persistence Strategy
   When using Redis for data persistence, you also need to consider some persistence strategies to better control the saving and recovery of data.

The following are some common persistence strategy code examples:

• Execute the SAVE command every 5 seconds:

  CONFIG SET save "5 1"

• Execute the BGSAVE command for each write operation to Redis and save the data to the disk:

  CONFIG SET appendfsync always

• Execute the BGSAVE command once per second to save the data to the disk:

  CONFIG SET appendfsync everysec

• Execute the BGSAVE command for every 1MB write command to save the data to disk:

  CONFIG SET appendfsync always
  CONFIG SET appendonly yes
  CONFIG SET auto-aof-rewrite-min-size 1mb
  CONFIG SET auto-aof-rewrite-percentage 100

Conclusion
Redis provides a variety of data For persistence methods, you can choose the appropriate method according to specific needs. This article introduces Redis's RDB persistence, AOF persistence, hybrid persistence and some persistence strategies, and gives corresponding code examples. By rationally using the persistence mechanism of Redis, the persistence and reliability of data can be guaranteed.

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