InnoDB automatically configures the
Only consider enabling
innodb_dedicated_server if the
MySQL instance resides on a dedicated server where it can use all
available system resources. For example, consider enabling if you
run MySQL Server in a Docker container or dedicated VM that only
runs MySQL. Enabling
innodb_dedicated_server is not
recommended if the MySQL instance shares system resources with
The information that follows describes how each variable is automatically configured.
Buffer pool size is configured according to the amount of memory detected on the server.
Table 15.8 Automatically Configured Buffer Pool Size
Detected Server Memory Buffer Pool Size Less than 1GB 128MiB (the default value) 1GB to 4GB
detected server memory* 0.5
Greater than 4GB
detected server memory* 0.75
As of MySQL 8.0.14, log file size is configured according to the automatically configured buffer pool size.
Table 15.9 Automatically Configured Log File Size
Buffer Pool Size Log File Size Less than 8GB 512MiB 8GB to 128GB 1024MiB Greater than 128GB 2048MiB
Prior to MySQL 8.0.14, the
innodb_log_file_sizevariable was automatically configured according to the amount of memory detected on the server, as shown below:
Table 15.10 Automatically Configured Log File Size (MySQL 8.0.13 and Earlier)
Detected Server Memory Log File Size < 1GB 48MiB (the default value) <= 4GB 128MiB <= 8GB 512MiB <= 16GB 1024MiB > 16GB 2048MiB
The number of log files is configured according to the automatically configured buffer pool size (in gigabytes). Automatic configuration of the
innodb_log_files_in_groupvariable was added in MySQL 8.0.14.
Table 15.11 Automatically Configured Number of Log Files
Buffer Pool Size Number of Log Files Less than 8GB ROUND(
buffer pool size)
8GB to 128GB ROUND(
buffer pool size* 0.75)
Greater than 128GB 64
innodb_log_files_in_groupvalue of 2 is enforced if the rounded buffer pool size value is less than 2GB.
O_DIRECTduring flushing I/O, but skips the
fsync()system call after each write operation.Warning
Prior to MySQL 8.0.14, this setting is not suitable for file systems such as XFS and EXT4, which require an
fsync()system call to synchronize file system metadata changes.
As of MySQL 8.0.14,
fsync()is called after creating a new file, after increasing file size, and after closing a file, to ensure that file system metadata changes are synchronized. The
fsync()system call is still skipped after each write operation.
Data loss is possible if redo log files and data files reside on different storage devices, and an unexpected exit occurs before data file writes are flushed from a device cache that is not battery-backed. If you use or intend to use different storage devices for redo log files and data files, and your data files reside on a device with a cache that is not battery-backed, use
If an automatically configured option is configured explicitly in
an option file or elsewhere, the explicitly specified setting is
used, and a startup warning similar to this is printed to
[Warning]  InnoDB: Option innodb_dedicated_server is ignored for innodb_buffer_pool_size because innodb_buffer_pool_size=134217728 is specified explicitly.
Explicit configuration of one option does not prevent the automatic configuration of other options.
configured explicitly in an option file,
still automatically configured based on a buffer pool size value
calculated according to the amount of memory detected on the
server, even though that value is not used to configure the size
of the buffer pool.
Automatically configured settings are evaluated and reconfigured if necessary each time the MySQL server is started.