MySQL指令顯示目前設定變數？

要顯示目前設定變數，可以使用show指令。語法如下 -

show variables;

您可以使用 LIKE 運算子進一步重寫上述語法。語法如下 -

show variables like ‘%anyStringValue%’;

查詢如下，顯示了取得一些設定變數的範例 -

mysql> show variables like '%max%';

輸出

+------------------------------------------------------+----------------------+
| Variable_name                                        | Value                |
+------------------------------------------------------+----------------------+
| binlog_max_flush_queue_time                          | 0                    |
| cte_max_recursion_depth                              | 1000                 |
| ft_max_word_len                                      | 84                   | 
| group_concat_max_len                                 | 1024                 |
| histogram_generation_max_mem_size                    | 20000000             |
| innodb_adaptive_max_sleep_delay                      | 150000               |
| innodb_change_buffer_max_size                        | 25                   |
| innodb_compression_pad_pct_max                       | 50                   |
| innodb_ft_max_token_size                             | 84                   |
| innodb_io_capacity_max                               | 2000                 |
| innodb_max_dirty_pages_pct                           | 90.000000            |
| innodb_max_dirty_pages_pct_lwm                       | 10.000000            |
| innodb_max_purge_lag                                 | 0                    |
| innodb_max_purge_lag_delay                           | 0                    |
| innodb_max_undo_log_size                             | 1073741824           |
| innodb_online_alter_log_max_size                     | 134217728            |
| max_allowed_packet                                   | 4194304              |
| 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 |
| max_length_for_sort_data                             | 4096                 |
| max_points_in_geometry                               | 65536                |
| max_prepared_stmt_count                              | 16382                |
| max_relay_log_size                                   | 0                    |
| max_seeks_for_key                                    | 4294967295           |
| max_sort_length                                      | 1024                 |
| max_sp_recursion_depth                               | 0                    |
| max_user_connections                                 | 0                    |
| max_write_lock_count                                 | 4294967295           |
| myisam_max_sort_file_size                            | 107374182400         |
| mysqlx_max_allowed_packet                            | 67108864             |
| mysqlx_max_connections                               | 100                  |
| optimizer_trace_max_mem_size                         | 1048576              |
| parser_max_mem_size                                  | 18446744073709551615 |
| performance_schema_max_cond_classes                  | 80                   |
| performance_schema_max_cond_instances                | -1                   |
| performance_schema_max_digest_length                 | 1024                 |
| performance_schema_max_digest_sample_age             | 60                   |
| performance_schema_max_file_classes                  | 80                   |
| performance_schema_max_file_handles                  | 32768                |
| performance_schema_max_file_instances                | -1                   |
| performance_schema_max_index_stat                    | -1                   |
| performance_schema_max_memory_classes                | 450                  |
| performance_schema_max_metadata_locks                | -1                   |
| performance_schema_max_mutex_classes                 | 300                  |
| performance_schema_max_mutex_instances               | -1                   |
| performance_schema_max_prepared_statements_instances | -1                   |
| performance_schema_max_program_instances             | -1                   |
| performance_schema_max_rwlock_classes                | 60                   |
| performance_schema_max_rwlock_instances              | -1                   |
| performance_schema_max_socket_classes                | 10                   |
| performance_schema_max_socket_instances              | -1                   |
| performance_schema_max_sql_text_length               | 1024                 |
| performance_schema_max_stage_classes                 | 150                  |
| performance_schema_max_statement_classes             | 212                  |
| performance_schema_max_statement_stack               | 10                   |
| performance_schema_max_table_handles                 | -1                   |
| performance_schema_max_table_instances               | -1                   |
| performance_schema_max_table_lock_stat               | -1                   | 
| performance_schema_max_thread_classes                | 100                  |
| performance_schema_max_thread_instances              | -1                   |
| range_optimizer_max_mem_size                         | 8388608              |
| slave_max_allowed_packet                             | 1073741824           |
| slave_pending_jobs_size_max                          | 134217728            |
| temptable_max_ram                                    | 1073741824           |
+------------------------------------------------------+----------------------+
74 rows in set (0.01 sec)

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