MySQL 8.0: Persisted Variables

小咪咪 2023-10-18 22:01 98阅读 0赞

###  ###

[14 August, 2018][14 August_ 2018][Jesper Krogh][]

Contents

*  [Persisting Variables][]
 *  [mysqld-auto.cnf and variables\_info][mysqld-auto.cnf and variables_info]
 *  [Backup and Restore][]
 *  [PERSIST\_ONLY Variables][PERSIST_ONLY Variables]

[Tweet][]

MySQL 8.0 introduced a new feature that allows you to persist configuration changes from inside MySQL. Previously you could execute `SET GLOBAL` to change the configuration at runtime, but you needed to update your MySQL configuration file in order to persist the change. In MySQL 8.0 you can skip the second step. This blog discuss how this works and how to backup and restore the configuration.

[![Using SET PERSIST to set a variable and the persisted\_variables table in the Performance Schema to get a list of persisted variables.][Using SET PERSIST to set a variable and the persisted_variables table in the Performance Schema to get a list of persisted variables.]][Using SET PERSIST to set a variable and the persisted_variables table in the Performance Schema to get a list of persisted variables._Using SET PERSIST to set a variable and the persisted_variables table in the Performance Schema to get a list of persisted variables.]

Using SET PERSIST to set a variable and the persisted\_variables table in the Performance Schema to get a list of persisted variables.

#### Persisting Variables ####

You persist changes with either the `SET PERSIST` or `SET PERSIST_ONLY` statement. The different is that `SET PERSIST_ONLY` only updates the configuration whereas `SET PERSIST`essentially combines `SET GLOBAL` and `SET PERSIST_ONLY`.

Information

Some variables such as `innodb_buffer_pool_instances` can only use `PERSIST_ONLY`, i.e. it requires a restart to make the changes take effect. Still others, such as `datadir`, requires *cryptographically signed* `SET` *statements*which are available in MySQL 8.0.14 and later.

#### mysqld-auto.cnf and variables\_info ####

The persisted variables are stored in the file `mysqld-auto.cnf` located in the data directory using the JSON format. It includes more information than just the persisted value. It also includes information such as who made the change and when. An example file is:

<table> 
 <tbody> 
 <tr> 
 <td> <code>shell$ cat mysqld</code><code>-</code><code>auto.cnf </code> <code>{ </code><code>"Version"</code> <code>: </code><code>1</code> <code>, </code><code>"mysql_server"</code> <code>: { </code><code>"sort_buffer_size"</code> <code>: { </code><code>"Value"</code> <code>: </code><code>"32768"</code> <code>, </code><code>"Metadata"</code> <code>: { </code><code>"Timestamp"</code> <code>: </code><code>1534230053297668</code> <code>, </code><code>"User"</code> <code>: </code><code>"root"</code> <code>, </code><code>"Host"</code> <code>: </code><code>"localhost"</code> <code>} } , </code><code>"join_buffer_size"</code> <code>: { </code><code>"Value"</code> <code>: </code><code>"131072"</code> <code>, </code><code>"Metadata"</code> <code>: { </code><code>"Timestamp"</code> <code>: </code><code>1534230072956789</code> <code>, </code><code>"User"</code> <code>: </code><code>"root"</code> <code>, </code><code>"Host"</code> <code>: </code><code>"localhost"</code> <code>} } , </code><code>"mysql_server_static_options"</code> <code>: { </code><code>"slave_parallel_type"</code> <code>: { </code><code>"Value"</code> <code>: </code><code>"LOGICAL_CLOCK"</code> <code>, </code><code>"Metadata"</code> <code>: { </code><code>"Timestamp"</code> <code>: </code><code>1534230099583642</code> <code>, </code><code>"User"</code> <code>: </code><code>"root"</code> <code>, </code><code>"Host"</code> <code>: </code><code>"localhost"</code> <code>} } } } }</code> </td> 
 </tr> 
 </tbody> 
</table>

Since it is JSON, it is easy to reformat to make easier to read, for example:

<table> 
 <tbody> 
 <tr> 
 <td> <code>shell$ cat mysqld</code><code>-</code><code>auto.cnf | python </code><code>-</code><code>m json.tool</code> <code>{ </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Version"</code><code>: </code><code>1</code><code>,</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"mysql_server"</code><code>: { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"join_buffer_size"</code><code>: { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Metadata"</code><code>: { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Host"</code><code>: </code><code>"localhost"</code><code>,</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Timestamp"</code><code>: </code><code>1534230072956789</code><code>,</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"User"</code><code>: </code><code>"root"</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>},</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Value"</code><code>: </code><code>"131072"</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>},</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"mysql_server_static_options"</code><code>: { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"slave_parallel_type"</code><code>: { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Metadata"</code><code>: { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Host"</code><code>: </code><code>"localhost"</code><code>,</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Timestamp"</code><code>: </code><code>1534230099583642</code><code>,</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"User"</code><code>: </code><code>"root"</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>},</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Value"</code><code>: </code><code>"LOGICAL_CLOCK"</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>},</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"sort_buffer_size"</code><code>: { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Metadata"</code><code>: { </code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Host"</code><code>: </code><code>"localhost"</code><code>,</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Timestamp"</code><code>: </code><code>1534230053297668</code><code>,</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"User"</code><code>: </code><code>"root"</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>},</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>"Value"</code><code>: </code><code>"32768"</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;</code><code>}</code> <code>}</code> </td> 
 </tr> 
 </tbody> 
</table>

This information is also available from the [performance\_schema.variables\_info][performance_schema.variables_info] table:

<table> 
 <tbody> 
 <tr> 
 <td> <code>mysql&gt; </code><code>SELECT</code> <code>VARIABLE_NAME, VARIABLE_SOURCE, sys.format_path(VARIABLE_PATH) </code><code>AS</code> <code>Path,</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>SET_TIME, SET_USER, SET_HOST</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>FROM</code> <code>performance_schema.variables_info</code> <code>&nbsp;&nbsp;</code><code>WHERE</code> <code>VARIABLE_NAME </code><code>IN</code> <code>(</code><code>'join_buffer_size'</code><code>, </code><code>'slave_parallel_type'</code><code>, </code><code>'sort_buffer_size'</code><code>);</code> <code>+</code><code>---------------------+-----------------+-------------------------------------------+----------------------------+----------+-----------+</code> <code>| VARIABLE_NAME&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | VARIABLE_SOURCE | Path&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | SET_TIME&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | SET_USER | SET_HOST&nbsp; |</code> <code>+</code><code>---------------------+-----------------+-------------------------------------------+----------------------------+----------+-----------+</code> <code>| join_buffer_size&nbsp;&nbsp;&nbsp; | </code><code>DYNAMIC</code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <code>|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | 2018-08-14 17:08:15.526750 | root&nbsp;&nbsp;&nbsp;&nbsp; | localhost |</code> <code>| slave_parallel_type | PERSISTED&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | @@datadir/mysqld-auto.cnf/mysqld-auto.cnf | 2018-08-14 17:01:39.583642 | root&nbsp;&nbsp;&nbsp;&nbsp; | localhost |</code> <code>| sort_buffer_size&nbsp;&nbsp;&nbsp; | PERSISTED&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | @@datadir/mysqld-auto.cnf&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | 2018-08-14 17:00:53.297668 | root&nbsp;&nbsp;&nbsp;&nbsp; | localhost |</code> <code>+</code><code>---------------------+-----------------+-------------------------------------------+----------------------------+----------+-----------+</code> <code>3 </code><code>rows</code> <code>in</code> <code>set</code> <code>(0.36 sec)</code> </td> 
 </tr> 
 </tbody> 
</table>

Notice that the source for `join_buffer_size` is `DYNAMIC` whereas the two other variables have the source set to `PERSISTED`. Why? After all they all three existed in the `mysqld-auto.cnf` file. `DYNAMIC` means that the variable was changes since the last restart either using `SET GLOBAL` or `SET PERSIST`. Another thing to be aware of is that variables changed with `SET PERSIST_ONLY` will not show up in `variables_info` until after the next restart. I will soon get back to show a way to get the variables that have been persisted in one way or another.

#### Backup and Restore ####

As a simple way to back up the configuration is simply copy the `mysqld-auto.cnf` file to a safe location. Similarly, you can restore the configuration by copying it back.

However, what if you want most of the configuration but not everything or you want to edit some of the values? In that case you need another way of exporting the configuration as you should not manually edit `mysqld-auto.cnf`.

Warning

Do not edit the `mysqld-auto.cnf` file manually. It should only be changed with `SET PERSIST` and `SET PERSIST_ONLY`. If there are any errors in the file, MySQL will refuse to start.

Fortunately as it turns out, it is easy to export all persisted variables. The table [performance\_schema.persisted\_variables][performance_schema.persisted_variables] includes all variables that has either been read from `mysqld-auto.cnf` or has been changed with `SET PERSIST` or `SET PERSIST_ONLY`since the last restart. The table include the persisted values. For example:

<table> 
 <tbody> 
 <tr> 
 <td> <code>mysql&gt; </code><code>SELECT</code> <code>* </code><code>FROM</code> <code>performance_schema.persisted_variables;</code> <code>+</code><code>---------------------+----------------+</code> <code>| VARIABLE_NAME&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | VARIABLE_VALUE |</code> <code>+</code><code>---------------------+----------------+</code> <code>| sort_buffer_size&nbsp;&nbsp;&nbsp; | 32768&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code> <code>| join_buffer_size&nbsp;&nbsp;&nbsp; | 131072&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |</code> <code>| slave_parallel_type | LOGICAL_CLOCK&nbsp; |</code> <code>+</code><code>---------------------+----------------+</code> <code>3 </code><code>rows</code> <code>in</code> <code>set</code> <code>(0.01 sec)</code> </td> 
 </tr> 
 </tbody> 
</table>

This can be used to create `SET` statements that can be used to recreate the configuration on another instance. For example:

<table> 
 <tbody> 
 <tr> 
 <td> 1 2 3 4 5 6 </td> 
 <td> <code>SELECT CONCAT('SET PERSIST_ONLY ', VARIABLE_NAME, ' = ',</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>IF(VARIABLE_VALUE REGEXP '^([0-9]+|ON|OFF|YES|NO)$',</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>VARIABLE_VALUE,</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>QUOTE(VARIABLE_VALUE)), ';'</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>) AS SetStmt</code> <code>&nbsp;&nbsp;</code><code>FROM performance_schema.persisted_variables;</code> </td> 
 </tr> 
 </tbody> 
</table>

Using the `mysql` command-line client, you can avoid the column names and table format by using the `--skip-column-names` and `--batch` options:

<table> 
 <tbody> 
 <tr> 
 <td> <code>shell$ mysql </code><code>--skip-column-names --batch \</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>-e </code><code>"SELECT CONCAT('SET PERSIST_ONLY ', VARIABLE_NAME, ' = ', IF(VARIABLE_VALUE REGEXP '^([0-9]+|ON|OFF|YES|NO)$', VARIABLE_VALUE, QUOTE(VARIABLE_VALUE)), ';') FROM performance_schema.persisted_variables;"</code> <code>\</code> <code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</code><code>&gt; config.sql</code> </td> 
 </tr> 
 </tbody> 
</table>

Note

On Microsoft Windows ensure everything is on one line and the backslashes are removed.

Now the file `config.sql` contains an export of the persisted variables:

<table> 
 <tbody> 
 <tr> 
 <td> <code>shell$ cat config.sql </code> <code>SET</code> <code>PERSIST_ONLY sort_buffer_size = 32768;</code> <code>SET</code> <code>PERSIST_ONLY join_buffer_size = 131072;</code> <code>SET</code> <code>PERSIST_ONLY slave_parallel_type = </code><code>'LOGICAL_CLOCK'</code><code>;</code> </td> 
 </tr> 
 </tbody> 
</table>

This example creates `SET PERSIST_ONLY` statement as those will work with all persistable variables. When you replay the `SET` statements, it will require a restart of MySQL for the changes to take effect. If you want to use `SET PERSIST` where possible, then you need to take into consideration whether the variable support `SET PERSIST`. A list of variables that require `SET PERSIST_ONLY` are included at the end.

The configuration can now be restored as:

<table> 
 <tbody> 
 <tr> 
 <td> <code>mysql&gt; SOURCE config.sql</code> <code>Query OK, 0 </code><code>rows</code> <code>affected (0.00 sec)</code> &nbsp; <code>Query OK, 0 </code><code>rows</code> <code>affected (0.00 sec)</code> &nbsp; <code>Query OK, 0 </code><code>rows</code> <code>affected (0.01 sec)</code> &nbsp; <code>mysql&gt; RESTART;</code> <code>Query OK, 0 </code><code>rows</code> <code>affected (0.00 sec)</code> </td> 
 </tr> 
 </tbody> 
</table>

#### PERSIST\_ONLY Variables ####

As promised, I will conclude with a list of persistable variables that only supports `SET PERSIST_ONLY`. As of MySQL 8.0.12 without any plugins installed, the variables are:

<table> 
 <tbody> 
 <tr> 
 <td> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 </td> 
 <td> <code>back_log</code> <code>binlog_gtid_simple_recovery</code> <code>disabled_storage_engines</code> <code>disconnect_on_expired_password</code> <code>ft_max_word_len</code> <code>ft_min_word_len</code> <code>ft_query_expansion_limit</code> <code>innodb_adaptive_hash_index_parts</code> <code>innodb_api_disable_rowlock</code> <code>innodb_api_enable_binlog</code> <code>innodb_api_enable_mdl</code> <code>innodb_autoinc_lock_mode</code> <code>innodb_buffer_pool_chunk_size</code> <code>innodb_buffer_pool_instances</code> <code>innodb_doublewrite</code> <code>innodb_flush_method</code> <code>innodb_force_recovery</code> <code>innodb_ft_aux_table</code> <code>innodb_ft_cache_size</code> <code>innodb_ft_min_token_size</code> <code>innodb_ft_server_stopword_table</code> <code>innodb_ft_sort_pll_degree</code> <code>innodb_ft_total_cache_size</code> <code>innodb_ft_user_stopword_table</code> <code>innodb_log_file_size</code> <code>innodb_log_files_in_group</code> <code>innodb_monitor_disable</code> <code>innodb_monitor_enable</code> <code>innodb_monitor_reset</code> <code>innodb_monitor_reset_all</code> <code>innodb_numa_interleave</code> <code>innodb_open_files</code> <code>innodb_page_cleaners</code> <code>innodb_purge_threads</code> <code>innodb_read_io_threads</code> <code>innodb_rollback_on_timeout</code> <code>innodb_sort_buffer_size</code> <code>innodb_sync_array_size</code> <code>innodb_tmpdir</code> <code>innodb_use_native_aio</code> <code>innodb_write_io_threads</code> <code>large_pages</code> <code>log_slave_updates</code> <code>log_syslog</code> <code>log_syslog_facility</code> <code>log_syslog_include_pid</code> <code>log_syslog_tag</code> <code>lower_case_table_names</code> <code>max_digest_length</code> <code>metadata_locks_cache_size</code> <code>metadata_locks_hash_instances</code> <code>myisam_mmap_size</code> <code>myisam_recover_options</code> <code>mysqlx_bind_address</code> <code>mysqlx_port</code> <code>mysqlx_port_open_timeout</code> <code>mysqlx_socket</code> <code>mysqlx_ssl_ca</code> <code>mysqlx_ssl_capath</code> <code>mysqlx_ssl_cert</code> <code>mysqlx_ssl_cipher</code> <code>mysqlx_ssl_crl</code> <code>mysqlx_ssl_crlpath</code> <code>mysqlx_ssl_key</code> <code>ngram_token_size</code> <code>old</code> <code>open_files_limit</code> <code>performance_schema</code> <code>performance_schema_digests_size</code> <code>performance_schema_error_size</code> <code>performance_schema_events_stages_history_long_size</code> <code>performance_schema_events_stages_history_size</code> <code>performance_schema_events_statements_history_long_size</code> <code>performance_schema_events_statements_history_size</code> <code>performance_schema_events_transactions_history_long_size</code> <code>performance_schema_events_transactions_history_size</code> <code>performance_schema_events_waits_history_long_size</code> <code>performance_schema_events_waits_history_size</code> <code>performance_schema_max_cond_classes</code> <code>performance_schema_max_digest_length</code> <code>performance_schema_max_file_classes</code> <code>performance_schema_max_file_handles</code> <code>performance_schema_max_memory_classes</code> <code>performance_schema_max_mutex_classes</code> <code>performance_schema_max_rwlock_classes</code> <code>performance_schema_max_socket_classes</code> <code>performance_schema_max_sql_text_length</code> <code>performance_schema_max_stage_classes</code> <code>performance_schema_max_statement_classes</code> <code>performance_schema_max_statement_stack</code> <code>performance_schema_max_thread_classes</code> <code>performance_schema_session_connect_attrs_size</code> <code>rbr_exec_mode</code> <code>relay_log_recovery</code> <code>relay_log_space_limit</code> <code>report_host</code> <code>report_password</code> <code>report_port</code> <code>report_user</code> <code>skip_name_resolve</code> <code>skip_show_database</code> <code>slave_skip_errors</code> <code>ssl_cipher</code> <code>table_open_cache_instances</code> <code>thread_handling</code> <code>thread_stack</code> <code>tls_version</code> </td> 
 </tr> 
 </tbody> 
</table>

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[14 August_ 2018]: https://mysql.wisborg.dk/2018/08/14/mysql-8-0-persisted-variables/
[Jesper Krogh]: https://mysql.wisborg.dk/author/admin/
[Persisting Variables]: https://mysql.wisborg.dk/2018/08/14/mysql-8-0-persisted-variables/#Persisting-Variables
[mysqld-auto.cnf and variables_info]: https://mysql.wisborg.dk/2018/08/14/mysql-8-0-persisted-variables/#mysqld-autocnf-and-variables_info
[Backup and Restore]: https://mysql.wisborg.dk/2018/08/14/mysql-8-0-persisted-variables/#Backup-and-Restore
[PERSIST_ONLY Variables]: https://mysql.wisborg.dk/2018/08/14/mysql-8-0-persisted-variables/#PERSIST_ONLY-Variables
[Tweet]: https://twitter.com/intent/tweet?url=https%3A%2F%2Fmysql.wisborg.dk%2F2018%2F08%2F14%2Fmysql-8-0-persisted-variables%2F&via=JWKrogh
[Using SET PERSIST to set a variable and the persisted_variables table in the Performance Schema to get a list of persisted variables.]: https://imgconvert.csdnimg.cn/aHR0cHM6Ly9pMi53cC5jb20vbXlzcWwud2lzYm9yZy5kay93cC1jb250ZW50L3VwbG9hZHMvMjAxOC8wOC9zZXRfcGVyc2lzdC02MDB4MzAzLnBuZz9yZXNpemU9NjAwJTJDMzAz
[Using SET PERSIST to set a variable and the persisted_variables table in the Performance Schema to get a list of persisted variables._Using SET PERSIST to set a variable and the persisted_variables table in the Performance Schema to get a list of persisted variables.]: http://mysql.wisborg.dk/2018/08/14/mysql-8-0-persisted-variables/set_persist/
[performance_schema.variables_info]: https://dev.mysql.com/doc/refman/en/variables-info-table.html
[performance_schema.persisted_variables]: https://dev.mysql.com/doc/refman/en/persisted-variables-table.html