PolarDB分布式版创建全局二级索引

说明

以下示例均假设已经建好的分库数为8。

定义全局二级索引

示例

CREATE TABLE t_order (
 `id` bigint(11) NOT NULL AUTO_INCREMENT,
 `order_id` varchar(20) DEFAULT NULL,
 `buyer_id` varchar(20) DEFAULT NULL,
 `seller_id` varchar(20) DEFAULT NULL,
 `order_snapshot` longtext DEFAULT NULL,
 `order_detail` longtext DEFAULT NULL,
 PRIMARY KEY (`id`),
 GLOBAL INDEX `g_i_seller`(`seller_id`) dbpartition by hash(`seller_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by hash(`order_id`);

其中：

• 主表：t_order只分库不分表，分库的拆分方式为按照order_id列进行哈希。
• 索引表：g_i_seller只分库不分表，分库的拆分方式为按照seller_id列进行哈希，未指定覆盖列。
• 索引定义子句：GLOBAL INDEX `g_i_seller`(`seller_id`) dbpartition by hash(`seller_id`)。

通过SHOW INDEX查看索引信息，包含拆分键order_id上的局部索引，和seller_id、id、order_id上的GSI，其中seller_id为索引表的拆分键，id和order_id为默认的覆盖列（主键和主表的拆分键）。

说明

关于GSI的限制与约定，请参见如何使用全局二级索引 ，关于SHOW INDEX详细说明，请参见SHOW INDEX 。

show index from t_order;
+---------+------------+-------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+----------+---------------+
| TABLE   | NON_UNIQUE | KEY_NAME                | SEQ_IN_INDEX | COLUMN_NAME | COLLATION | CARDINALITY | SUB_PART | PACKED | NULL | INDEX_TYPE | COMMENT  | INDEX_COMMENT |
+---------+------------+-------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+----------+---------------+
| t_order |          0 | PRIMARY                 |            1 | id          | A         |           0 |     NULL | NULL   |      | BTREE      |          |               |
| t_order |          1 | auto_shard_key_order_id |            1 | order_id    | A         |           0 |     NULL | NULL   | YES  | BTREE      |          |               |
| t_order |          1 | g_i_seller              |            1 | seller_id   | NULL      |           0 |     NULL | NULL   | YES  | GLOBAL     | INDEX    |               |
| t_order |          1 | g_i_seller              |            2 | id          | NULL      |           0 |     NULL | NULL   |      | GLOBAL     | COVERING |               |
| t_order |          1 | g_i_seller              |            3 | order_id    | NULL      |           0 |     NULL | NULL   | YES  | GLOBAL     | COVERING |               |
+---------+------------+-------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+----------+---------------+

通过SHOW GLOBAL INDEX可以单独查看GSI信息。详细说明请参见SHOW GLOBAL INDEX。

 show global index from t_order;
+--------+---------+------------+------------+-------------+----------------+------------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+--------+
| SCHEMA | TABLE   | NON_UNIQUE | KEY_NAME   | INDEX_NAMES | COVERING_NAMES | INDEX_TYPE | DB_PARTITION_KEY | DB_PARTITION_POLICY | DB_PARTITION_COUNT | TB_PARTITION_KEY | TB_PARTITION_POLICY | TB_PARTITION_COUNT | STATUS |
+--------+---------+------------+------------+-------------+----------------+------------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+--------+
| d7     | t_order | 1          | g_i_seller | seller_id   | id, order_id   | NULL       | seller_id        | HASH                | 8                  |                  | NULL                | NULL               | PUBLIC |
+--------+---------+------------+------------+-------------+----------------+------------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+--------+

查看索引表的结构，索引表包含主表的主键、分库分表键和默认的覆盖列，主键列去除了AUTO_INCREMENT属性，并且去除了主表中的局部索引。

show create table g_i_seller;
+------------+-----------------------------------------------------------+
| Table      | Create Table                                              |
+------------+-----------------------------------------------------------+
| g_i_seller | CREATE TABLE `g_i_seller` (
 `id` bigint(11) NOT NULL,
 `order_id` varchar(20) DEFAULT NULL,
 `seller_id` varchar(20) DEFAULT NULL,
 PRIMARY KEY (`id`),
 KEY `auto_shard_key_seller_id` (`seller_id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by hash(`seller_id`) |
+------------+-----------------------------------------------------------+

定义全局唯一索引

CREATE TABLE t_order (
 `id` bigint(11) NOT NULL AUTO_INCREMENT,
 `order_id` varchar(20) DEFAULT NULL,
 `buyer_id` varchar(20) DEFAULT NULL,
 `seller_id` varchar(20) DEFAULT NULL,
 `order_snapshot` longtext DEFAULT NULL,
 `order_detail` longtext DEFAULT NULL,
 PRIMARY KEY (`id`),
 UNIQUE GLOBAL INDEX `g_i_buyer`(`buyer_id`) COVERING(`seller_id`, `order_snapshot`) 
   dbpartition by hash(`buyer_id`) tbpartition by hash(`buyer_id`) tbpartitions 3
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by hash(`order_id`);

其中：

• 主表：t_order 只分库不分表，分库的拆分方式为按照order_id列进行哈希。
• 索引表：g_i_buyer 只分库且分表，分库和分表的拆分方式均为按照buyer_id列进行哈希，覆盖列包含 seller_id和order_snapshot。
• 索引定义子句：UNIQUE GLOBAL INDEX `g_i_buyer`(`buyer_id`) COVERING(`seller_id`, `order_snapshot`) dbpartition by hash(`buyer_id`) tbpartition by hash(`buyer_id`) tbpartitions 3。

通过SHOW INDEX 查看索引信息，包含拆分键order_id上的局部索引，和buyer_id、id、order_id、seller_id和order_snapshot上的GSI，其中buyer_id为索引表的拆分键，id和order_id 为默认的覆盖列（主键和主表的拆分键），seller_id和order_snapshot为显示指定的覆盖列。

说明

关于GSI的限制与约定，请参见如何使用全局二级索引，关于SHOW INDEX详细说明，请参见SHOW INDEX 。

show index from t_order;
+--------------+------------+-------------------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+----------+---------------+
| TABLE        | NON_UNIQUE | KEY_NAME                | SEQ_IN_INDEX | COLUMN_NAME    | COLLATION | CARDINALITY | SUB_PART | PACKED | NULL | INDEX_TYPE | COMMENT  | INDEX_COMMENT |
+--------------+------------+-------------------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+----------+---------------+
| t_order_dthb |          0 | PRIMARY                 |            1 | id             | A         |           0 |     NULL | NULL   |      | BTREE      |          |               |
| t_order_dthb |          1 | auto_shard_key_order_id |            1 | order_id       | A         |           0 |     NULL | NULL   | YES  | BTREE      |          |               |
| t_order      |          0 | g_i_buyer               |            1 | buyer_id       | NULL      |           0 |     NULL | NULL   | YES  | GLOBAL     | INDEX    |               |
| t_order      |          1 | g_i_buyer               |            2 | id             | NULL      |           0 |     NULL | NULL   |      | GLOBAL     | COVERING |               |
| t_order      |          1 | g_i_buyer               |            3 | order_id       | NULL      |           0 |     NULL | NULL   | YES  | GLOBAL     | COVERING |               |
| t_order      |          1 | g_i_buyer               |            4 | seller_id      | NULL      |           0 |     NULL | NULL   | YES  | GLOBAL     | COVERING |               |
| t_order      |          1 | g_i_buyer               |            5 | order_snapshot | NULL      |           0 |     NULL | NULL   | YES  | GLOBAL     | COVERING |               |
+--------------+------------+-------------------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+----------+---------------+

通过SHOW GLOBAL INDEX可以单独查看GSI信息。详细说明请参见SHOW GLOBAL INDEX。

show global index from t_order;
+--------+---------+------------+-----------+-------------+-----------------------------------------+------------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+--------+
| SCHEMA | TABLE   | NON_UNIQUE | KEY_NAME  | INDEX_NAMES | COVERING_NAMES                          | INDEX_TYPE | DB_PARTITION_KEY | DB_PARTITION_POLICY | DB_PARTITION_COUNT | TB_PARTITION_KEY | TB_PARTITION_POLICY | TB_PARTITION_COUNT | STATUS |
+--------+---------+------------+-----------+-------------+-----------------------------------------+------------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+--------+
| d7     | t_order | 0          | g_i_buyer | buyer_id    | id, order_id, seller_id, order_snapshot | NULL       | buyer_id         | HASH                | 8                  | buyer_id         | HASH                | 3                  | PUBLIC |
+--------+---------+------------+-----------+-------------+-----------------------------------------+------------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+--------+      

查看索引表的结构，索引表包含主表的主键、分库分表键、默认覆盖列和GSI定义中指定的覆盖列，主键列去除了AUTO_INCREMENT属性，并且去除了主表中局部索引，全局唯一索引默认会创建一份数据表来实现全局的唯一性支持。

show create table g_i_buyer;
+-----------+--------------------------------------------------------------------------------------------------------+
| Table     | Create Table                                                                                           |
+-----------+--------------------------------------------------------------------------------------------------------+
| g_i_buyer | CREATE TABLE `g_i_buyer` (
  `id` bigint(11) NOT NULL,
  `order_id` varchar(20) DEFAULT NULL,
  `buyer_id` varchar(20) DEFAULT NULL,
  `seller_id` varchar(20) DEFAULT NULL,
  `order_snapshot` longtext,
  PRIMARY KEY (`id`),
  UNIQUE KEY `auto_shard_key_buyer_id` (`buyer_id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by hash(`buyer_id`) tbpartition by hash(`buyer_id`) tbpartitions 3 |
+-----------+--------------------------------------------------------------------------------------------------------+