Oracle 5.0, Reference Manual

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InnoDB
Startup Options and System Variables
1251
replication master server unless you have an unusual setup where only one thread is able to change
data.
For a server that is accepting data changes from only one thread, it is safe and recommended to
turn off this option to improve performance for
InnoDB
tables. For example, you can turn it off on
replication slaves where only the replication SQL thread is changing data.
You can also turn off this option if you do not need it for safe binary logging or replication, and you
also do not use an external XA transaction manager.
This variable was added in MySQL 5.0.3.
•
innodb_sync_spin_loops
Version Introduced 5.0.3
Command-Line Format
--innodb_sync_spin_loops=#
Option-File Format
innodb_sync_spin_loops
Option Sets Variable Yes,
innodb_sync_spin_loops
[1251]
Variable Name
innodb_sync_spin_loops
Variable Scope Global
Dynamic Variable Yes
The number of times a thread waits for an
InnoDB
mutex to be freed before the thread is
suspended. The default value is 20. This variable was added in MySQL 5.0.3.
•
innodb_table_locks
Command-Line Format
--innodb_table_locks
Option-File Format
innodb_table_locks
Option Sets Variable Yes,
innodb_table_locks
[1251]
Variable Name
innodb_table_locks
Variable Scope Global, Session
Dynamic Variable Yes
Permitted Values
Type
boolean
Default
TRUE
If
autocommit = 0
[436] ,
InnoDB
honors
LOCK TABLES
; MySQL does not return from
LOCK
TABLES ... WRITE
until all other threads have released all their locks to the table. The default
value of
innodb_table_locks
[1251] is 1, which means that
LOCK TABLES
causes InnoDB to
lock a table internally if
autocommit = 0
[436] .
•
innodb_thread_concurrency
Command-Line Format
--innodb_thread_concurrency=#
Option-File Format
innodb_thread_concurrency
Option Sets Variable Yes,
innodb_thread_concurrency
[1251]
Variable Name
innodb_thread_concurrency
Variable Scope Global
Dynamic Variable Yes
Permitted Values (>= 5.0.9)