MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
SHOW [GLOBAL | SESSION] VARIABLES
[LIKE 'pattern' | WHERE expr]
SHOW VARIABLES shows the values
of MySQL system variables (see
Section 7.1.8, “Server System Variables”). This statement does
not require any privilege. It requires only the ability to
connect to the server.
System variable information is also available from these sources:
Performance Schema tables. See Section 29.12.14, “Performance Schema System Variable Tables”.
The mysqladmin variables command. See Section 6.5.2, “mysqladmin — A MySQL Server Administration Program”.
For SHOW VARIABLES, a
LIKE clause, if present, indicates
which variable names to match. A WHERE clause
can be given to select rows using more general conditions, as
discussed in Section 28.8, “Extensions to SHOW Statements”.
SHOW VARIABLES accepts an
optional GLOBAL or SESSION
variable scope modifier:
With a
GLOBALmodifier, the statement displays global system variable values. These are the values used to initialize the corresponding session variables for new connections to MySQL. If a variable has no global value, no value is displayed.With a
SESSIONmodifier, the statement displays the system variable values that are in effect for the current connection. If a variable has no session value, the global value is displayed.LOCALis a synonym forSESSION.If no modifier is present, the default is
SESSION.
The scope for each system variable is listed at Section 7.1.8, “Server System Variables”.
SHOW VARIABLES is subject to a
version-dependent display-width limit. For variables with very
long values that are not completely displayed, use
SELECT as a workaround. For
example:
SELECT @@GLOBAL.innodb_data_file_path;
Most system variables can be set at server startup (read-only
variables such as
version_comment are
exceptions). Many can be changed at runtime with the
SET
statement. See Section 7.1.9, “Using System Variables”, and
Section 15.7.6.1, “SET Syntax for Variable Assignment”.
Partial output is shown here. The list of names and values may differ for your server. Section 7.1.8, “Server System Variables”, describes the meaning of each variable, and Section 7.1.1, “Configuring the Server”, provides information about tuning them.
mysql> SHOW VARIABLES;
+--------------------------------------------+------------------------------+
| Variable_name | Value |
+--------------------------------------------+------------------------------+
| activate_all_roles_on_login | OFF |
| auto_generate_certs | ON |
| auto_increment_increment | 1 |
| auto_increment_offset | 1 |
| autocommit | ON |
| automatic_sp_privileges | ON |
| avoid_temporal_upgrade | OFF |
| back_log | 151 |
| basedir | /usr/ |
| big_tables | OFF |
| bind_address | * |
| binlog_cache_size | 32768 |
| binlog_checksum | CRC32 |
| binlog_direct_non_transactional_updates | OFF |
| binlog_error_action | ABORT_SERVER |
| binlog_expire_logs_seconds | 2592000 |
| binlog_format | ROW |
| binlog_group_commit_sync_delay | 0 |
| binlog_group_commit_sync_no_delay_count | 0 |
| binlog_gtid_simple_recovery | ON |
| binlog_max_flush_queue_time | 0 |
| binlog_order_commits | ON |
| binlog_row_image | FULL |
| binlog_row_metadata | MINIMAL |
| binlog_row_value_options | |
| binlog_rows_query_log_events | OFF |
| binlog_stmt_cache_size | 32768 |
| binlog_transaction_dependency_history_size | 25000 |
| binlog_transaction_dependency_tracking | COMMIT_ORDER |
| block_encryption_mode | aes-128-ecb |
| bulk_insert_buffer_size | 8388608 |
...
| max_allowed_packet | 67108864 |
| max_binlog_cache_size | 18446744073709547520 |
| max_binlog_size | 1073741824 |
| max_binlog_stmt_cache_size | 18446744073709547520 |
| max_connect_errors | 100 |
| max_connections | 151 |
| max_delayed_threads | 20 |
| max_digest_length | 1024 |
| max_error_count | 1024 |
| max_execution_time | 0 |
| max_heap_table_size | 16777216 |
| max_insert_delayed_threads | 20 |
| max_join_size | 18446744073709551615 |
...
| thread_handling | one-thread-per-connection |
| thread_stack | 286720 |
| time_zone | SYSTEM |
| timestamp | 1530906638.765316 |
| tls_version | TLSv1.2,TLSv1.3 |
| tmp_table_size | 16777216 |
| tmpdir | /tmp |
| transaction_alloc_block_size | 8192 |
| transaction_allow_batching | OFF |
| transaction_isolation | REPEATABLE-READ |
| transaction_prealloc_size | 4096 |
| transaction_read_only | OFF |
| transaction_write_set_extraction | XXHASH64 |
| unique_checks | ON |
| updatable_views_with_limit | YES |
| version | 8.0.40 |
| version_comment | MySQL Community Server - GPL |
| version_compile_machine | x86_64 |
| version_compile_os | Linux |
| version_compile_zlib | 1.2.11 |
| wait_timeout | 28800 |
| warning_count | 0 |
| windowing_use_high_precision | ON |
+--------------------------------------------+------------------------------+
With a LIKE clause, the statement
displays only rows for those variables with names that match the
pattern. To obtain the row for a specific variable, use a
LIKE clause as shown:
SHOW VARIABLES LIKE 'max_join_size';
SHOW SESSION VARIABLES LIKE 'max_join_size';
To get a list of variables whose name match a pattern, use the
% wildcard character in a
LIKE clause:
SHOW VARIABLES LIKE '%size%';
SHOW GLOBAL VARIABLES LIKE '%size%';
Wildcard characters can be used in any position within the
pattern to be matched. Strictly speaking, because
_ is a wildcard that matches any single
character, you should escape it as \_ to
match it literally. In practice, this is rarely necessary.