MySQL 8.4 Release Notes
When the server is started with
--innodb-dedicated-server,
InnoDB automatically calculates values for and
sets the following system variables:
Note
innodb_redo_log_capacity supersedes both
innodb_log_file_size and
innodb_log_files_in_group,
which were set by --innodb-dedicated-server in
older versions of MySQL, but which have since been deprecated.
You should expect innodb_log_file_size and
innodb_log_files_in_group to be removed in a
future version of MySQL.
In MySQL 8.0,
innodb_flush_method was also
set automatically by this option, but in MySQL 8.4, this is no
longer the case.
You should consider using
--innodb-dedicated-server only if the MySQL
instance resides on a dedicated server where it can use all
available system resources—for example, if you run MySQL
Server in a Docker container or dedicated VM that runs MySQL only.
using --innodb-dedicated-server is not
recommended if the MySQL instance shares system resources with
other applications.
The value for each affected variable is determined and applied by
--innodb-dedicated-server as described in the
following list:
Buffer pool size is calculated according to the amount of memory detected on the server, as shown in the following table:
Table 17.8 Automatically Configured Buffer Pool Size
Detected Server Memory Buffer Pool Size Less than 1GB 128MB (the default value) 1GB to 4GB detected server memory* 0.5Greater than 4GB detected server memory* 0.75Redo log capacity is calculated according to the number of logical processors available on the server. The formula is (number of available logical processors / 2) GB, with a maximum dynamic default value of 16 GB.
innodb_log_file_size(deprecated)Log file size is set according to the automatically configured buffer pool size, as shown in the following table:
Table 17.9 Automatically Configured Log File Size
Buffer Pool Size Log File Size Less than 8GB 512MB 8GB to 128GB 1024MB Greater than 128GB 2048MB innodb_log_files_in_group(deprecated)The number of log files is determined according to the automatically configured buffer pool size, as shown in the following table:
Table 17.10 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
NoteThe minimum value for
innodb_log_files_in_groupvalue is2; this lower limit is enforced if the rounded buffer pool size value is less than this number.
If one of the variables listed previously is set explicitly in an
option file or elsewhere, this explicit value is used, and a
startup warning similar to this one is printed to
stderr:
[Warning] [000000] InnoDB: Option innodb_dedicated_server is ignored for innodb_buffer_pool_size because innodb_buffer_pool_size=134217728 is specified explicitly.
Setting one variable explicitly does not prevent the automatic configuration of other options.
If the server is started with
--innodb-dedicated-server and
innodb_buffer_pool_size is set
explicitly, variable settings based on buffer pool size use the
buffer pool size value calculated according to the amount of
memory detected on the server rather than the explicitly defined
buffer pool size value.
Note
Automatic configuration settings are applied by
--innodb-dedicated-server
only when the MySQL server is started. If
you later set any of the affected variables explicitly, this
overrides its predetermined value, and the value that was
explicitly set is applied. Setting one of these variables to
DEFAULT causes it to be set to the actual
default value as shown in the variable's description in the
Manual, and does not cause it to revert to
the value set by --innodb-dedicated-server. The
corresponding system variable
innodb_dedicated_server is changed only by
starting the server with
--innodb-dedicated-server (or with
--innodb-dedicated-server=ON or
--innodb-dedicated-server=OFF); it is otherwise
read-only.