查看规则和节点拓扑类语句

查看规则和节点拓扑类语句如下：

• SHOW RULE [FROM tablename] 语句
• SHOW FULL RULE [FROM tablename] 语句
• SHOW TOPOLOGY FROM tablename 语句
• SHOW PARTITIONS FROM tablename 语句
• SHOW BROADCASTS 语句
• SHOW DATASOURCES 语句
• SHOW NODE 语句

1. SHOW RULE [FROM tablename]

使用说明：

• show rule：查看数据库下每一个逻辑表的拆分情况；
• show rule from tablename：查看数据库下指定逻辑表的拆分情况。

重要列详解：

• BROADCAST：是否为广播表（0：否，1：是）；
• DB_PARTITION_KEY：分库的拆分键，没有分库的话，值为空；
• DB_PARTITION_POLICY：分库的拆分策略，取值包括哈希或 YYYYMM、YYYYDD、YYYYWEEK 等日期策略；
• DB_PARTITION_COUNT：分库数；
• TB_PARTITION_KEY：分表的拆分键，没有分表的话，值为空；
• TB_PARTITION_POLICY：分表的拆分策略，取值包括哈希或 MM、DD、MMDD、WEEK 等日期策略；
• TB_PARTITION_COUNT：分表数。

mysql> show rule;
+------+--------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
| ID   | TABLE_NAME   | BROADCAST | DB_PARTITION_KEY | DB_PARTITION_POLICY | DB_PARTITION_COUNT | TB_PARTITION_KEY | TB_PARTITION_POLICY | TB_PARTITION_COUNT |
+------+--------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
|    0 | dept_manager |         0 |                  | NULL                | 1                  |                  | NULL                | 1                  |
|    1 | emp          |         0 | emp_no           | hash                | 8                  | id               | hash                | 2                  |
|    2 | example      |         0 | shard_key        | hash                | 8                  |                  | NULL                | 1                  |
+------+--------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
3 rows in set (0.01 sec)

2. SHOW FULL RULE [FROM tablename]

查看数据库下逻辑表的拆分规则，比 SHOW RULE 指令展示的信息更加详细。

重要列详解：

• BROADCAST：是否为广播表（0：否，1：是）；
• JOIN_GROUP：保留字段，暂时无意义。
• ALLOW_FULL_TABLE_SCAN：分库分表在没有指定分表键值的情况下是否允许查询数据，如果配置为 true，此时需要扫描每一个物理表来查找出符合条件的数据，简称为全表扫描；
• DB_NAME_PATTERN：DB_NAME_PATTERN 中 {} 之间的 0 为占位符，执行 SQL 时会被 DB_RULES_STR 计算出的值替代，并保持位数。比如，DB_NAME_PATTERN 的值为 SEQ_{0000}_RDS，DB_RULES_STR 的值为 [1,2,3,4]，则会产生4个 DB_NAME，分别为 SEQ_0001_RDS、SEQ_0002_RDS、SEQ_0003_RDS、SEQ_0004_RDS；
• DB_RULES_STR：具体的分库规则；
• TB_NAME_PATTERN：TB_NAME_PATTERN 中 {} 之间的 0 为占位符，执行 SQL 时会被 TB_RULES_STR 计算出的值替代，并保持位数。比如，TB_NAME_PATTERN 的值为 table_{00}，TB_RULES_STR 的值为 [1,2,3,4,5,6,7,8]，则会产生8张表，分别为 table_01、table_02、table_03、table_04、table_05、table_06、table_07、table_08；
• TB_RULES_STR：分表规则；
• PARTITION_KEYS：分库和分表键集合，对于既分库又分表的情形，分库键在前，分表键在后；
• DEFAULT_DB_INDEX：单库单表存放的分库。

mysql> show full rule;
+------+--------------+-----------+------------+-----------------------+----------------------------------------------------+-----------------------------------------------------+-----------------+------------------------------------+----------------+--------------------------------------------------+
| ID   | TABLE_NAME   | BROADCAST | JOIN_GROUP | ALLOW_FULL_TABLE_SCAN | DB_NAME_PATTERN                                    | DB_RULES_STR                                        | TB_NAME_PATTERN | TB_RULES_STR                       | PARTITION_KEYS | DEFAULT_DB_INDEX                                 |
+------+--------------+-----------+------------+-----------------------+----------------------------------------------------+-----------------------------------------------------+-----------------+------------------------------------+----------------+--------------------------------------------------+
|    0 | dept_manager |         0 | NULL       |                     0 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0000_RDS   | NULL                                                | dept_manager    | NULL                               | NULL           | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0000_RDS |
|    1 | emp          |         0 | NULL       |                     1 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_{0000}_RDS | ((#emp_no,1,8#).longValue().abs() % 8)              | emp_{0}         | ((#id,1,2#).longValue().abs() % 2) | emp_no      id | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0000_RDS |
|    2 | example      |         0 | NULL       |                     1 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_{0000}_RDS | ((#shard_key,1,8#).longValue().abs() % 8).intdiv(1) | example         | NULL                               | shard_key      | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0000_RDS |
+------+--------------+-----------+------------+-----------------------+----------------------------------------------------+-----------------------------------------------------+-----------------+------------------------------------+----------------+--------------------------------------------------+
3 rows in set (0.01 sec)

3. SHOW TOPOLOGY FROM tablename

查看指定逻辑表的拓扑分布，展示该逻辑表保存在哪些分库中，每个分库下包含哪些分表。

mysql> show topology from emp;
+------+--------------------------------------------------+------------+
| ID   | GROUP_NAME                                       | TABLE_NAME |
+------+--------------------------------------------------+------------+
|    0 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0000_RDS | emp_0      |
|    1 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0000_RDS | emp_1      |
|    2 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0001_RDS | emp_0      |
|    3 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0001_RDS | emp_1      |
|    4 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0002_RDS | emp_0      |
|    5 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0002_RDS | emp_1      |
|    6 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0003_RDS | emp_0      |
|    7 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0003_RDS | emp_1      |
|    8 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0004_RDS | emp_0      |
|    9 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0004_RDS | emp_1      |
|   10 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0005_RDS | emp_0      |
|   11 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0005_RDS | emp_1      |
|   12 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0006_RDS | emp_0      |
|   13 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0006_RDS | emp_1      |
|   14 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0007_RDS | emp_0      |
|   15 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0007_RDS | emp_1      |
+------+--------------------------------------------------+------------+
16 rows in set (0.01 sec)

4. SHOW PARTITIONS FROM tablename

查看分库分表键集合，分库键和分表键之间用逗号分割。如果最终结果有两个值，说明是既分库又分表的情形，第一个是分库键，第二个是分表键。如果结果只有一个值，说明是分库不分表的情形，该值是分库键。

mysql> show partitions from emp;        
+-----------+
| KEYS      |
+-----------+
| emp_no,id |
+-----------+
1 row in set (0.00 sec)

5. SHOW BROADCASTS

查看广播表列表。

mysql> show broadcasts;
+------+------------+
| ID   | TABLE_NAME |
+------+------------+
|    0 | brd2       |
|    1 | brd_tbl    |
+------+------------+
2 rows in set (0.01 sec)

6. SHOW DATASOURCES

查看底层存储信息，包含数据库名、数据库分组名、连接信息、用户名、底层存储类型、读写权重、连接池信息等。

重要列详解：

• SCHEMA：数据库名；
• GROUP：数据库分组名。分组的目标是管理多组数据完全相同的数据库，比如通过 RDS（MySQL）进行数据复制后的主备数据库。主要用来解决读写分离、主备切换的问题；
• URL：底层 RDS（MySQL）的连接信息；
• TYPE：底层存储类型，目前只支持 RDS（MySQL)；
• READ_WEIGHT：读权重。在主实例的读压力比较大的时候，可以通过 DRDS 读写分离功能将读流量进行分流，减轻 RDS 主实例的压力。DRDS 会自动识别读写流量，引导写流量进入 RDS 主实例，读流量则按配置的权重流向所有 RDS 实例；
• WRITE_WEIGHT：写权重。解释见上。

mysql> show datasources;
+------+----------------------------+------------------------------------------------+--------------------------------------------------+----------------------------------------------------------------------------------+-----------+-------+------+------+------+--------------+----------+--------------+---------------+----------------------------------------------+-------------+--------------+
| ID   | SCHEMA                     | NAME                                           | GROUP                                            | URL                                                                              | USER      | TYPE  | INIT | MIN  | MAX  | IDLE_TIMEOUT | MAX_WAIT | ACTIVE_COUNT | POOLING_COUNT | ATOM                                         | READ_WEIGHT | WRITE_WEIGHT |
+------+----------------------------+------------------------------------------------+--------------------------------------------------+----------------------------------------------------------------------------------+-----------+-------+------+------+------+--------------+----------+--------------+---------------+----------------------------------------------+-------------+--------------+
|    0 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0000_iiab_1 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0000_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0000 | jnkinsea0 | mysql | 0    | 24   | 72   | 15           | 5000     | 0            | 1             | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0000_iiab | 10          | 10           |
|    1 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0001_iiab_2 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0001_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0001 | jnkinsea0 | mysql | 0    | 24   | 72   | 15           | 5000     | 0            | 1             | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0001_iiab | 10          | 10           |
|    2 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0002_iiab_3 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0002_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0002 | jnkinsea0 | mysql | 0    | 24   | 72   | 15           | 5000     | 0            | 1             | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0002_iiab | 10          | 10           |
|    3 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0003_iiab_4 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0003_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0003 | jnkinsea0 | mysql | 0    | 24   | 72   | 15           | 5000     | 0            | 1             | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0003_iiab | 10          | 10           |
|    4 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0004_iiab_5 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0004_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0004 | jnkinsea0 | mysql | 0    | 24   | 72   | 15           | 5000     | 0            | 1             | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0004_iiab | 10          | 10           |
|    5 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0005_iiab_6 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0005_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0005 | jnkinsea0 | mysql | 0    | 24   | 72   | 15           | 5000     | 0            | 1             | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0005_iiab | 10          | 10           |
|    6 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0006_iiab_7 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0006_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0006 | jnkinsea0 | mysql | 0    | 24   | 72   | 15           | 5000     | 0            | 1             | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0006_iiab | 10          | 10           |
|    7 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0007_iiab_8 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0007_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0007 | jnkinsea0 | mysql | 0    | 24   | 72   | 15           | 5000     | 0            | 1             | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0007_iiab | 10          | 10           |
+------+----------------------------+------------------------------------------------+--------------------------------------------------+----------------------------------------------------------------------------------+-----------+-------+------+------+------+--------------+----------+--------------+---------------+----------------------------------------------+-------------+--------------+
8 rows in set (0.01 sec)

7. SHOW NODE

查看物理库的读写次数（历史累计数据）、读写权重（历史累计数据）。

重要列详解：

• MASTER_READ_COUNT：RDS 主实例处理的只读查询次数（历史累计数据）；
• SLAVE_READ_COUNT：RDS 备实例处理的只读查询次数（历史累计数据）；
• MASTER_READ_PERCENT：RDS 主实例处理的只读查询占比（注意该列显示的是累计的实际数据占比，并不是用户配置的百分比）；
• SLAVE_READ_PERCENT：RDS 备实例处理的只读查询占比（注意该列显示的是累计的实际数据占比，并不是用户配置的百分比）。

注意：

• 事务中的只读查询会被发送到 RDS 主实例；
• 由于MASTER_READ_PERCENT，SLAVE_READ_PERCENT这两列代表的是历史累计数据，更改读写权重的配比后，这几个数值并不能立即反应最新的读写权重配比，需累计一段比较长的时间才行。

mysql> show node;
+------+--------------------------------------------------+-------------------+------------------+---------------------+--------------------+
| ID   | NAME                                             | MASTER_READ_COUNT | SLAVE_READ_COUNT | MASTER_READ_PERCENT | SLAVE_READ_PERCENT |
+------+--------------------------------------------------+-------------------+------------------+---------------------+--------------------+
| 0    | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0000_RDS |                12 |                0 | 100%                | 0%                 |
| 1    | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0001_RDS |                 0 |                0 | 0%                  | 0%                 |
| 2    | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0002_RDS |                 0 |                0 | 0%                  | 0%                 |
| 3    | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0003_RDS |                 0 |                0 | 0%                  | 0%                 |
| 4    | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0004_RDS |                 0 |                0 | 0%                  | 0%                 |
| 5    | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0005_RDS |                 0 |                0 | 0%                  | 0%                 |
| 6    | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0006_RDS |                 0 |                0 | 0%                  | 0%                 |
| 7    | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0007_RDS |                 0 |                0 | 0%                  | 0%                 |
+------+--------------------------------------------------+-------------------+------------------+---------------------+--------------------+
8 rows in set (0.01 sec)