CREATE INDEX_DDL_SQL 手册_分布式关系型数据库 DRDS_阿里云技术文档

DRDS 支持创建局部索引和全局二级索引 (Global Secondary Index, GSI) ，同时支持删除这两种索引。

注意：DRDS 全局二级索引要求 MySQL 版本 >= 5.7, 并且 DRDS 版本 >= 5.4.1，基本原理请参考 DRDS 全局二级索引文档

局部索引

参考 MySQL CREATE INDEX 文档。

全局二级索引

语法：

CREATE [UNIQUE]
    GLOBAL INDEX index_name [index_type]
    ON tbl_name (index_sharding_col_name,...)
    global_secondary_index_option
    [index_option]
    [algorithm_option | lock_option] ...
# 全局二级索引特有语法，具体说明请参考 CREATE TABLE 文档
global_secondary_index_option:
    [COVERING (col_name,...)]
    drds_partition_options
# 分库分表子句，具体说明请参考 CREATE TABLE 文档
drds_partition_options:
    DBPARTITION BY db_sharding_algorithm
    [TBPARTITION BY {table_sharding_algorithm} [TBPARTITIONS num]]
db_sharding_algorithm:
    HASH([col_name])
  | {YYYYMM|YYYYWEEK|YYYYDD|YYYYMM_OPT|YYYYWEEK_OPT|YYYYDD_OPT}(col_name)
  | UNI_HASH(col_name)
  | RIGHT_SHIFT(col_name, n)
  | RANGE_HASH(col_name, col_name, n)
table_sharding_algorithm:
    HASH(col_name)
  | {MM|DD|WEEK|MMDD|YYYYMM|YYYYWEEK|YYYYDD|YYYYMM_OPT|YYYYWEEK_OPT|YYYYDD_OPT}(col_name)
  | UNI_HASH(col_name)
  | RIGHT_SHIFT(col_name, n)
  | RANGE_HASH(col_name, col_name, n) 
# 以下为 MySQL DDL 语法
index_sharding_col_name:
    col_name [(length)] [ASC | DESC] # length 参数仅用于在索引表拆分键上创建局部索引
index_option:
    KEY_BLOCK_SIZE [=] value
  | index_type
  | WITH PARSER parser_name
  | COMMENT 'string'
index_type:
    USING {BTREE | HASH}
algorithm_option:
    ALGORITHM [=] {DEFAULT|INPLACE|COPY}
lock_option:
    LOCK [=] {DEFAULT|NONE|SHARED|EXCLUSIVE}

CREATE GLOBAL INDEX 系列语法用于在建表后添加 GSI，该系列语法在 MySQL 语法上新引入了 GLOBAL 关键字，用于指定添加的索引类型为 GSI。目前建表后创建 GSI 存在一定限制，GSI 的限制与约定参考 DRDS 全局二级索引使用文档

全局二级索引定义子句详细说明，参考 CREATE TABLE 文档

示例

下面以建立普通全局二级索引为例，介绍在建表后创建 GSI

# 先建表
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`),
  KEY `l_i_order` (`order_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by hash(`order_id`);
# 再建全局二级索引
CREATE GLOBAL INDEX `g_i_seller` ON t_order (`seller_id`) dbpartition by hash(`seller_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
索引定义子句：GLOBAL INDEX `g_i_seller` ON t_order (`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, order_id 为默认的覆盖列（主键和主表的拆分键）

注意： GSI 的限制与约定参考 DRDS 全局二级索引使用文档，SHOW INDEX 详细说明参考 SHOW INDEX 文档

mysql> 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 | l_i_order  |            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，详细说明参考 SHOW GLOBAL INDEX 文档

mysql> 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 |
+---------------------+---------+------------+------------+-------------+----------------+------------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+--------+
| ZZY3_DRDS_LOCAL_APP | t_order | 1          | g_i_seller | seller_id   | id, order_id   | NULL       | seller_id        | HASH                | 4                  |                  | 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、默认的覆盖列和自定义覆盖列，主键列去除了 AUTO_INCREMENT 属性，并且去除了主表中的局部索引

mysql> 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`) |
+------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

CREATE INDEX_DDL_SQL 手册_分布式关系型数据库 DRDS

CREATE INDEX

局部索引

全局二级索引

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