innodb_log_buffer_size
Command-Line Format
System Variable Name innodb_log_buffer_size
Variable Scope Global
Dynamic Variable No
Permitted Values Type integer
Default 8388608
Min Value 262144
Max Value 4294967295
The size in bytes of the buffer that InnoDB uses to write to the log files on disk.
The default value is 8MB. A large log buffer enables large transactions to run without a 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 general I/O tuning advice, see Section 8.5.8, “Optimizing InnoDB Disk I/O”.
buffer 大小單位bytes,InnoDB 用於寫log files 到磁盤,默認值是8M,
一個大的log buffer 讓一個大的事務運行不需要寫日志到磁盤在事務提交前,因此,如果你有事務比如update,insert或者delete 很多的記錄, 讓log buffer 足夠大來節約磁盤I/O.
對於常規的I/O 調優建議,see Section 8.5.8, “Optimizing InnoDB Disk I/O”.
The size in bytes of the buffer pool, the memory area where InnoDB caches table and index data. The default value is 128MB.
The maximum value depends on the CPU architecture; the maximum is 4294967295 (232-1) on 32-bit systems and 18446744073709551615 (264-1) on 64-bit systems.
On 32-bit systems, the CPU architecture and operating system may impose a lower practical maximum size than the stated maximum.
buffer pool 的大小單位字節, InnoDB 的內存區域用於cached 表和索引數據,默認是128MB。
最大值依賴CPU 結構, maximum是 4294967295 (232-1) 在32位系統上 在64位系統上是 18446744073709551615 (264-1)
在32位系統上,CPU 結構和操作系統可能施加較低的實際的最大值 相比規定的最大值
When the size of the buffer pool is greater than 1GB, setting innodb_buffer_pool_instances to a value greater than 1 can improve the scalability on a busy server.
The larger you set this value, the less disk I/O is needed to access the same data in tables more than once. On a dedicated database server,
you might set this to up to 80% of the machine physical memory size. Be prepared to scale back this value if these other issues occur:
Competition for physical memory might cause paging in the operating system.
當 buffer pool 大小大於1GB,設置innodb_buffer_pool_instances 大於1來改善 可擴展性在一個繁忙的server上
值你設置的越大,越少的disk I/O 訪問相同的數據, 在一個專用的database server.
你可以設置最多到80%的機器物理內存大小，物理內存的競爭可能導致操作系統中的交換
InnoDB reserves additional memory for buffers and control structures, so that the total allocated space is approximately 10% greater than the specified size.
The address space must be contiguous, which can be an issue on Windows systems with DLLs that load at specific addresses.
The time to initialize the buffer pool is roughly proportional to its size. On large installations, this initialization time might be significant.
For example, on a modern Linux x86_64 server, initialization of a 10GB buffer pool takes approximately 6 seconds. See Section 8.10.1, “The InnoDB Buffer Pool”.
InnoDB儲備額外的內存用於緩沖區和控制結構, 因此總共分配的空間是大約10%大於指定值。
地址空間必須是連續的, 在Windows上可能是一個問題用DLLs來加載特定的地址
