Solution to the problem that MySQL database innodb cannot start and cannot restart

Problem Introduction

The computer froze during use, and after restarting, it was found that mysql did not start successfully. Checking the error log found that innodb issues 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 the mysql startup

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

Delete ib_logfile*

Delete ibdata*

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

Restart mysql

Re-establish the database or use the backup to overwrite

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

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

innodb_force_recovery can be set to1-6, large numbers include the influence of all the numbers before them

　　　　 1, (SRV_FORCE_IGNORE_CORRUPT): Ignore the corrupt pages detected.

　　　　 2, (SRV_FORCE_NO_BACKGROUND): Prevent the main thread from running, such as when the main thread needs to execute full purge operation, it will cause crash.

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

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

　　　　 5, (SRV_FORCE_NO_UNDO_LOG_SCAN): Do not view the redo log, InnoDB storage engine will treat uncommitted transactions as committed.

　　　　 6, (SRV_FORCE_NO_LOG_REDO): Do not perform the rollforward operation.

Add to my.cnf (on Windows it is my.ini)

innodb_force_recovery = 6 
innodb_purge_thread = 0

Restart mysql

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

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

That is all the content of this article, I hope it can help everyone in learning or using mysql. If you have any questions, you can leave a message for communication, thank you for your support of the Yana Tutorial.