SHOW [GLOBAL|SESSION] VARIABLES
SHOW [GLOBAL|SESSION] VARIABLES 语句用于显示 GLOBAL 或 SESSION 范围的变量列表。如果未指定范围，则应用默认范围 SESSION。
语法图
- ShowVariablesStmt
- ShowLikeOrWhere
ShowVariablesStmt ::=
"SHOW" ("GLOBAL" | "SESSION")? VARIABLES ShowLikeOrWhere?
ShowLikeOrWhere ::=
"LIKE" SimpleExpr
| "WHERE" Expression
示例
以下示例展示了如何使用 SHOW [GLOBAL|SESSION] VARIABLES 语句查看变量名或变量值符合特定模式的变量。关于这些变量的详细说明，参见系统变量和语法。
SHOW GLOBAL VARIABLES LIKE 'tidb_stmt_summary%';
+-------------------------------------+---------------------+
| Variable_name | Value |
+-------------------------------------+---------------------+
| tidb_stmt_summary_enable_persistent | OFF |
| tidb_stmt_summary_file_max_backups | 0 |
| tidb_stmt_summary_file_max_days | 3 |
| tidb_stmt_summary_file_max_size | 64 |
| tidb_stmt_summary_filename | tidb-statements.log |
| tidb_stmt_summary_history_size | 24 |
| tidb_stmt_summary_internal_query | OFF |
| tidb_stmt_summary_max_sql_length | 4096 |
| tidb_stmt_summary_max_stmt_count | 3000 |
| tidb_stmt_summary_refresh_interval | 1800 |
+-------------------------------------+---------------------+
10 rows in set (0.001 sec)
SHOW GLOBAL VARIABLES LIKE 'time_zone%';
+---------------+--------+
| Variable_name | Value |
+---------------+--------+
| time_zone | SYSTEM |
+---------------+--------+
1 row in set (0.00 sec)
SHOW VARIABLES WHERE Variable_name="tidb_window_concurrency";
+-------------------------+-------+
| Variable_name | Value |
+-------------------------+-------+
| tidb_window_concurrency | -1 |
+-------------------------+-------+
1 row in set (0.00 sec)
SHOW VARIABLES WHERE Value=300;
+--------------------------------+-------+
| Variable_name | Value |
+--------------------------------+-------+
| ddl_slow_threshold | 300 |
| delayed_insert_timeout | 300 |
| innodb_purge_batch_size | 300 |
| key_cache_age_threshold | 300 |
| slave_checkpoint_period | 300 |
| tidb_slow_log_threshold | 300 |
| tidb_wait_split_region_timeout | 300 |
+--------------------------------+-------+
7 rows in set (0.00 sec)
MySQL 兼容性
SHOW [GLOBAL|SESSION] VARIABLES 语句与 MySQL 完全兼容。如发现任何兼容性差异，请尝试 TiDB 支持资源。