What is the function of innodb_fast_shutdown parameter in mysql
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When mysql is turned off, the parameter innodb_fast_shutdown affects the behavior that the storage engine of the table is innodb. The parameter is 0, 1, 2, and 3 values.
0, which means that when MYSQL shuts down, Innodb needs to complete all full purge and merge insert buffer operations, which takes time to complete. If you do an Innodb plugin upgrade, you usually need to set this parameter to 0, and then shut down the database
1, which is the default value of the parameter, there is no need to complete full purge and merge insert buffer operations, but some dirty pages in the buffer pool will still be flushed to disk.
2 means that full purge and merge insert buffer operations do not need to be completed, and dirty pages of data in the buffer pool are not written back to disk. Instead, the logs are written to the log file. Nothing will be lost this way, but mysql will perform a restore operation (recovery) the next time it starts
If it was in the case of innodb_fast_shutdown=2 or mysql crash the last time innodb was closed, it uses redo log to redo transactions that have already been committed.
The next operation process is:
(1)。 Rollback uncompleted transitions cancels transactions that are not committed
(2)。 Purge all clears useless undo pages
(3)。 Merge insert buffer merge insert buffer
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