Persistence of redis

RDB        

              advantage ： For disaster recovery , Commonly used to back up files （ Multithreaded representation ） Allow the use of big data Faster restart , The file is relatively small , Improve redis performance

                shortcoming ： Caused by emergencies redis Stopping will lose data , The last persistent data may be lost , Memory consumption

               save “”  Means closing rdb

How to trigger a snapshot   

                 perform flushall command , There will be dump.rdb file , But it's empty , meaningless

                 Be careful not to manually operate in the production environment save Taking pictures

Restore data     

                 Will back up files (dump.rdb) Move to redis Install the directory and start the service

                CONFIG GET dir Get directory

AOF                 

                principle ： Log every write operation in the form of a log , take Redis All written instructions executed are recorded ( Reading operation does not record ), Only files can be added but not rewritten ,redis At the beginning of startup, it will read the file and rebuild the data , In other words ,redis In case of restart, execute the write instruction from the front to the back according to the contents of the log file to complete the data recovery

Aof What is kept is appendonly.aof file

        appendonly The default is no   yes Open for indication aof Persistence         

advantage ： Higher data integrity , append mode , File rewriting is possible   You can open it directly to watch

shortcoming ： Larger files , Performance may lead to poor , The data may have bug, Maybe the data will be different

How to choose

1. Cache only （RDB）
2. Do user login and save session conversation （RDB+AOF）
3. The ultimate pursuit of performance （ close RDB, Open copy ）
4. Ultimate pursuit of safety （RDB+AOF (appendfsync always)）