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long-running back-end operations, such as a transform step in a data warehouse that waits for other large insert or update operations to finish. 

innodb_lock_wait_timeout  applies to InnoDB  row locks. A MySQL table lock does not happen inside InnoDB  and this timeout does not apply to waits for table locks. 

The lock wait timeout value does not apply to deadlocks when innodb_deadlock_detect is enabled (the default) because InnoDB  detects deadlocks immediately and rolls back one of the deadlocked transactions. When innodb_deadlock_detect  is disabled, InnoDB  relies on innodb_lock_wait_timeout  for transaction rollback when a deadlock occurs. See Section 15.7.5.2, “Deadlock Detection” . 

innodb_lock_wait_timeout  can be set at runtime with the SET GLOBAL  or SET SESSION statement. Changing the GLOBAL  setting requires privileges sufficient to set global system variables (see Section 5.1.9.1, “System Variable Privileges” ) and affects the operation of all clients that subsequently connect. Any client can change the SESSION  setting for innodb_lock_wait_timeout , which affects only that client. 

• innodb_log_buffer_size 

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The size in bytes of the buffer that InnoDB  uses to write to the log files on disk. The default is 16MB. A large log buffer enables large transactions to run without the need to write the log to disk before the transactions commit. Thus, if you have transactions that update, insert, or delete many rows, making the log buffer larger saves disk I/O. For related information, see Memory Configuration, and Section 8.5.4, “Optimizing InnoDB Redo Logging” . For general I/O tuning advice, see Section 8.5.8, “Optimizing InnoDB Disk I/O” . 

• innodb_log_checkpoint_fuzzy_now 

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