Solution to the problem that MySQL database innodb fails to start and cannot be restarted_MySQL

Problem introduction

The computer crashed during use. After restarting, I found that mysql did not start successfully. Looking at the error log, I found that there was a problem with innodb that caused mysql to fail to start.

Error log

$ mysql.server start
Starting MySQL
. ERROR! The server quit without updating PID file (/usr/local/var/mysql/fdipzonedeMacBook-Air.local.pid).

22:08:37 mysqld_safe Starting mysqld daemon with databases from /usr/local/var/mysql
2016-04-23 22:08:38 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2016-04-23 22:08:38 0 [Note] /usr/local/Cellar/mysql/5.6.24/bin/mysqld (mysqld 5.6.24) starting as process 3604 ...
2016-04-23 22:08:38 3604 [Warning] Setting lower_case_table_names=2 because file system for /usr/local/var/mysql/ is case insensitive
2016-04-23 22:08:38 3604 [Note] Plugin 'FEDERATED' is disabled.
2016-04-23 22:08:38 3604 [Note] InnoDB: Using atomics to ref count buffer pool pages
2016-04-23 22:08:38 3604 [Note] InnoDB: The InnoDB memory heap is disabled
2016-04-23 22:08:38 3604 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2016-04-23 22:08:38 3604 [Note] InnoDB: Memory barrier is not used
2016-04-23 22:08:38 3604 [Note] InnoDB: Compressed tables use zlib 1.2.3
2016-04-23 22:08:38 3604 [Note] InnoDB: Using CPU crc32 instructions
2016-04-23 22:08:38 3604 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2016-04-23 22:08:38 3604 [Note] InnoDB: Completed initialization of buffer pool
2016-04-23 22:08:38 3604 [Note] InnoDB: Highest supported file format is Barracuda.
2016-04-23 22:08:38 3604 [Note] InnoDB: Log scan progressed past the checkpoint lsn 68929933440
2016-04-23 22:08:38 3604 [Note] InnoDB: Database was not shutdown normally!
2016-04-23 22:08:38 3604 [Note] InnoDB: Starting crash recovery.
2016-04-23 22:08:38 3604 [Note] InnoDB: Reading tablespace information from the .ibd files...
2016-04-23 22:08:38 3604 [ERROR] InnoDB: checksum mismatch in tablespace ./test_user/user_recommend_code#P#pmax.ibd (table test_user/user_recommend_code#P#pmax)
2016-04-23 22:08:38 3604 [Note] InnoDB: Page size:1024 Pages to analyze:64
2016-04-23 22:08:38 3604 [Note] InnoDB: Page size: 1024, Possible space_id count:0
2016-04-23 22:08:38 3604 [Note] InnoDB: Page size:2048 Pages to analyze:48
2016-04-23 22:08:38 3604 [Note] InnoDB: Page size: 2048, Possible space_id count:0
2016-04-23 22:08:38 3604 [Note] InnoDB: Page size:4096 Pages to analyze:24
2016-04-23 22:08:38 3604 [Note] InnoDB: Page size: 4096, Possible space_id count:0
2016-04-23 22:08:38 3604 [Note] InnoDB: Page size:8192 Pages to analyze:12
2016-04-23 22:08:38 3604 [Note] InnoDB: Page size: 8192, Possible space_id count:0
2016-04-23 22:08:38 3604 [Note] InnoDB: Page size:16384 Pages to analyze:6
2016-04-23 22:08:38 3604 [Note] InnoDB: VALID: space:2947354 page_no:3 page_size:16384
2016-04-23 22:08:38 3604 [Note] InnoDB: Page size: 16384, Possible space_id count:1
2016-04-23 22:08:38 3604 [Note] InnoDB: space_id:2947354, Number of pages matched: 1/1 (16384)
2016-04-23 22:08:38 3604 [Note] InnoDB: Chosen space:2947354

2016-04-23 22:08:38 3604 [Note] InnoDB: Restoring page 0 of tablespace 2947354
2016-04-23 22:08:38 3604 [Warning] InnoDB: Doublewrite does not have page_no=0 of space: 2947354
2016-04-23 22:08:38 7fff79b9e300 InnoDB: Operating system error number 2 in a file operation.
InnoDB: The error means the system cannot find the path specified.
InnoDB: If you are installing InnoDB, remember that you must create
InnoDB: directories yourself, InnoDB does not create them.
InnoDB: Error: could not open single-table tablespace file ./test_user/user_recommend_code#P#pmax.ibd
InnoDB: We do not continue the crash recovery, because the table may become
InnoDB: corrupt if we cannot apply the log records in the InnoDB log to it.
InnoDB: To fix the problem and start mysqld:
InnoDB: 1) If there is a permission problem in the file and mysqld cannot
InnoDB: open the file, you should modify the permissions.
InnoDB: 2) If the table is not needed, or you can restore it from a backup,
InnoDB: then you can remove the .ibd file, and InnoDB will do a normal
InnoDB: crash recovery and ignore that table.
InnoDB: 3) If the file system or the disk is broken, and you cannot remove
InnoDB: the .ibd file, you can set innodb_force_recovery > 0 in my.cnf
InnoDB: and force InnoDB to continue crash recovery here.

Solution

1. If the data is not important or there is already a backup, you only need to restore mysql startup

Enter the mysql directory, usually: /usr/local/var/mysql/

Delete ib_logfile*

Delete ibdata*

Delete all database physical directories (for example, if the database is test_db, execute rm -rf test_db)

Restart mysql

Rebuild the database or overwrite it with a backup

2. If the data is important and there is no backup

You can use the innodb_force_recovery parameter to make mysqld skip the recovery step, start mysqld, export the data and rebuild the database.

innodb_force_recovery can be set to 1-6, the larger number includes the impact of all previous numbers

1. (SRV_FORCE_IGNORE_CORRUPT): Ignore the detected corrupt page.

2. (SRV_FORCE_NO_BACKGROUND): Prevent the main thread from running. If the main thread needs to perform a full purge operation, it will cause a crash.

3. (SRV_FORCE_NO_TRX_UNDO): Do not perform transaction rollback operation.

4. (SRV_FORCE_NO_IBUF_MERGE): Do not perform the merge operation of insert buffers.

5. (SRV_FORCE_NO_UNDO_LOG_SCAN): Without checking the redo log, the InnoDB storage engine will treat uncommitted transactions as committed.

6. (SRV_FORCE_NO_LOG_REDO): Do not perform roll forward operation.

Add
to my.cnf (windows is my.ini)

innodb_force_recovery = 6 
innodb_purge_thread = 0

Restart mysql

At this time, only select, create, and drop operations can be performed, but insert, update, and delete operations cannot be performed

Execute logical export. After completion, set innodb_force_recovery=0, innodb_purge_threads=1, then rebuild the database, and finally re-import the exported data

Summary

The above is the entire content of this article. I hope it will be helpful to everyone when learning or using mysql. If you have any questions, you can leave a message to communicate. Thank you for your support.