CREATE TABLE（DRDS模式） - PolarDB

本文主要介紹使用DDL語句進行建表的文法、子句、參數和基本方式。本文法僅適用於DRDS模式資料庫。

文法

CREATE [SHADOW] TABLE [IF NOT EXISTS] tbl_name
    (create_definition, ...)
    [table_options]
    [drds_partition_options]

create_definition:
    col_name column_definition
  | mysql_create_definition
  | [UNIQUE] GLOBAL INDEX index_name [index_type] (index_sharding_col_name,...)
      [global_secondary_index_option]
      [index_option] ...

# 全域二級索引相關
global_secondary_index_option:
    [COVERING (col_name,...)]
    [drds_partition_options]
    [VISIBLE|INVISIBLE]

# 分庫分表子句
drds_partition_options:
    DBPARTITION BY db_partition_algorithm
    [TBPARTITION BY table_partition_algorithm [TBPARTITIONS num]]
    [LOCALITY=locality_option]

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)

# 可以在建立單表時指定該表的儲存位置
locality_option:
    'dn=storage_inst_id_list'

storage_inst_id_list:
    storage_inst_id[,storage_inst_id_list]
    
# 以下為MySQL DDL文法
index_sharding_col_name:
    col_name [(length)] [ASC | DESC]

index_option:
    KEY_BLOCK_SIZE [=] value
  | index_type
  | WITH PARSER parser_name
  | COMMENT 'string'

index_type:
    USING {BTREE | HASH}

說明

標準版不支援分庫分表文法。
PolarDB-X DDL文法基於MySQL文法，以上主要列出了差異部分，詳細文法請參見MySQL 文檔。

分庫分表子句和參數

DBPARTITION BY hash(partition_key)：指定分庫鍵和分庫演算法。
TBPARTITION BY { HASH(column) | {MM|DD|WEEK|MMDD|YYYYMM|YYYYWEEK|YYYYDD|YYYYMM_OPT|YYYYWEEK_OPT|YYYYDD_OPT}(column)（可選）：預設與DBPARTITION BY相同，指定物理表使用什麼方式映射資料。
TBPARTITIONS num（可選）：每個庫上的物理表數目（預設為1），如不分表，就不需要指定該欄位。
拆分函數的詳細介紹，請參見拆分函數。

定義全域二級索引的子句及參數

[UNIQUE] GLOBAL：定義全域二級索引，UNIQUE GLOBAL代表全域唯一索引。
index_name：索引名，也是索引表的名稱。
index_type：索引表中分庫分表鍵上局部索引的類型，支援範圍請參見MySQL 文檔。
index_sharding_col_name,...：索引列，包含且僅包含索引表的全部分庫分表鍵。詳情請參見全域二級索引。
global_secondary_index_option：PolarDB-X全域二級索引的擴充文法。
- COVERING (col_name,...)：覆蓋列，索引表中除索引列以外的其他列，預設包含主鍵和主表的分庫分表鍵。詳情請參見全域二級索引。
- drds_partition_options：索引表的分庫分表子句，詳情請參見分庫分表子句和參數。
index_option：索引表中分庫分表鍵上局部索引的屬性，詳情請參見MySQL 文檔。

全鏈路壓測影子表子句

SHADOW：建立全鏈路壓測影子表，表名必須以_test_為首碼，首碼後的表名部分必須與關聯的正式表名一致，且正式表必須先於影子表建立。

LOCALITY

通過LOCALITY指定單表的儲存位置。

說明

通過LOCALITY文法指定了資料庫或單表的位置之後，不支援再修改該庫或該表的儲存位置。
資料庫中單表的儲存位置不受該庫儲存位置的影響。建立單表時若未指定儲存位置，則會被隨機放置在一個儲存節點上，且後續該PolarDB-X執行個體上建立的所有未指定儲存位置的單表，均會被放置在該儲存節點上。

單庫單表

建一張單庫單表，不做任何拆分。

CREATE TABLE single_tbl(
 id bigint not null auto_increment, 
 name varchar(30), 
 primary key(id)
);

查看邏輯表的節點拓撲，可以看出只在0庫建立了一張單庫單表的邏輯表。

show topology from single_tbl;
+------+------------------------------------------------------------------+------------+
| ID   | GROUP_NAME                                                       | TABLE_NAME |
+------+------------------------------------------------------------------+------------+
|    0 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | single_tbl |
+------+------------------------------------------------------------------+------------+
1 row in set (0.01 sec)

假設已有一個PolarDB-X執行個體，該執行個體上已有polardbx-storage-0-master和polardbx-storage-1-master兩個儲存節點，其中polardbx-storage-1-master上已建立了一個資料庫db1。現需要在db1庫中建立一張表，並指定其的儲存位置為polardbx-storage-0-master，文法如下：

CREATE TABLE tb1 (id int) LOCALITY='dn=polardbx-storage-0-master';

建立成功後，您可以通過如下語句查看該表的拓撲結構：

SHOW TOPOLOGY FROM tb1;

返回結果如下：

+----+------------------+------------+
| ID | GROUP_NAME       | TABLE_NAME | 
+----+------------------+------------+
| 0  | DB1_000000_GROUP | tb1        |
+----+------------------+------------+
1 row in set

說明以上返回結果表示tb1表位於DB1_000000_GROUP分庫。

分庫不分表

假設已經建好的分庫數為8，建一張表，只分庫不分表，分庫方式為根據ID列雜湊。

CREATE TABLE multi_db_single_tbl(
  id bigint not null auto_increment, 
  name varchar(30), 
  primary key(id)
) dbpartition by hash(id);

查看該邏輯表的節點拓撲，可以看出在每個分庫都建立了1張分表，即只做了分庫。

show topology from multi_db_single_tbl;
+------+------------------------------------------------------------------+---------------------+
| ID   | GROUP_NAME                                                       | TABLE_NAME          |
+------+------------------------------------------------------------------+---------------------+
|    0 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | multi_db_single_tbl |
|    1 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | multi_db_single_tbl |
|    2 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0002_RDS | multi_db_single_tbl |
|    3 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0003_RDS | multi_db_single_tbl |
|    4 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0004_RDS | multi_db_single_tbl |
|    5 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0005_RDS | multi_db_single_tbl |
|    6 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0006_RDS | multi_db_single_tbl |
|    7 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | multi_db_single_tbl |
+------+------------------------------------------------------------------+---------------------+
8 rows in set (0.01 sec)

分庫分表

您可以使用如下拆分方式進行分庫分表：

使用雜湊函數做拆分
使用雙欄位雜湊函數做拆分
使用日期做拆分

說明

以下樣本均假設已經建好的分庫數為8。

使用雜湊函數做拆分

建一張表，既分庫又分表，每個庫含有3張物理表，分庫拆分方式為按照ID列進行雜湊，分表拆分方式為按照bid列進行雜湊。您可以先根據ID列的值進行雜湊運算，將表中資料分布在多個子庫中，每個子庫中的資料再根據bid列值的雜湊運算結果分布在3個物理表中。

CREATE TABLE multi_db_multi_tbl(
 id bigint not null auto_increment, 
 bid int, 
 name varchar(30), 
 primary key(id)
) dbpartition by hash(id) tbpartition by hash(bid) tbpartitions 3;

查看該邏輯表的節點拓撲，可以看出在每個分庫都建立了3張分表。

show topology from multi_db_multi_tbl;
+------+------------------------------------------------------------------+-----------------------+
| ID   | GROUP_NAME                                                       | TABLE_NAME            |
+------+------------------------------------------------------------------+-----------------------+
|    0 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | multi_db_multi_tbl_00 |
|    1 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | multi_db_multi_tbl_01 |
|    2 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | multi_db_multi_tbl_02 |
|    3 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | multi_db_multi_tbl_03 |
|    4 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | multi_db_multi_tbl_04 |
|    5 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | multi_db_multi_tbl_05 |
|    6 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0002_RDS | multi_db_multi_tbl_06 |
|    7 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0002_RDS | multi_db_multi_tbl_07 |
|    8 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0002_RDS | multi_db_multi_tbl_08 |
|    9 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0003_RDS | multi_db_multi_tbl_09 |
|   10 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0003_RDS | multi_db_multi_tbl_10 |
|   11 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0003_RDS | multi_db_multi_tbl_11 |
|   12 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0004_RDS | multi_db_multi_tbl_12 |
|   13 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0004_RDS | multi_db_multi_tbl_13 |
|   14 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0004_RDS | multi_db_multi_tbl_14 |
|   15 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0005_RDS | multi_db_multi_tbl_15 |
|   16 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0005_RDS | multi_db_multi_tbl_16 |
|   17 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0005_RDS | multi_db_multi_tbl_17 |
|   18 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0006_RDS | multi_db_multi_tbl_18 |
|   19 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0006_RDS | multi_db_multi_tbl_19 |
|   20 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0006_RDS | multi_db_multi_tbl_20 |
|   21 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | multi_db_multi_tbl_21 |
|   22 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | multi_db_multi_tbl_22 |
|   23 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | multi_db_multi_tbl_23 |
+------+------------------------------------------------------------------+-----------------------+
24 rows in set (0.01 sec)

查看該邏輯表的拆分規則，可以看出分庫分表的拆分方式均為雜湊，分庫的拆分鍵為ID，分表的拆分鍵為bid。

show rule from multi_db_multi_tbl;
+------+--------------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
| ID   | TABLE_NAME         | BROADCAST | DB_PARTITION_KEY | DB_PARTITION_POLICY | DB_PARTITION_COUNT | TB_PARTITION_KEY | TB_PARTITION_POLICY | TB_PARTITION_COUNT |
+------+--------------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
|    0 | multi_db_multi_tbl |         0 | id               | hash                | 8                  | bid              | hash                | 3                  |
+------+--------------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
1 row in set (0.01 sec)

使用雙欄位雜湊函數做拆分

使用要求拆分鍵的類型必須是字元類型或數字類型。
路由方式根據任一拆分鍵後N位計算雜湊值，以雜湊方式完成路由計算。N為函數第三個參數。例如RANGE_HASH(COL1, COL2, N)，計算時會優先選擇COL1，截取其後N位進行計算。COL1不存在時按COL2計算。
適用情境適合於需要有兩個拆分鍵，並且僅使用其中一個拆分索引值進行查詢時的情境。假設使用者的PolarDB-X裡已經分了8個物理庫，現業務有如下的情境：
- 一個業務想按買家ID和訂單ID對訂單表進行分庫。
- 查詢時條件僅有買家ID或訂單ID。

此時可使用以下DDL對訂單表進行構建：

create table test_order_tb (
 id bigint not null auto_increment,
 seller_id varchar(30) DEFAULT NULL,
 order_id varchar(30) DEFAULT NULL,
 buyer_id varchar(30) DEFAULT NULL,
 create_time datetime DEFAULT NULL,
 primary key(id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by RANGE_HASH(buyer_id, order_id, 10) tbpartition by RANGE_HASH(buyer_id, order_id, 10) tbpartitions 3;

說明

兩個拆分鍵皆不能修改。
插入資料時如果發現兩個拆分鍵指向不同的分庫或分表時，插入會失敗。

使用日期做拆分

除了可以使用雜湊函數做拆分演算法，您還可以使用日期函數MM、DD、WEEK或MMDD來作為分表的拆分演算法，具體步驟請參見如下樣本。

建一張表，既分庫又分表，分庫方式為根據userId列雜湊，分表方式為根據actionDate列，按照一周七天來拆分（WEEK(actionDate)計算的是DAY_OF_WEEK）。

比如actionDate列的值是2017-02-27，這天是星期一，WEEK(actionDate)算出的值是2，該條記錄就會被儲存到2（2 % 7 = 2）這張分表（位於某個分庫，具體的表名是 user_log_2）；比如actionDate列的值是2017-02-26，這天是星期天，WEEK(actionDate)算出的值是1，該條記錄就會被儲存到1（1 % 7 = 1）這張分表（位於某個分庫，具體的表名是 user_log_1）。

CREATE TABLE user_log(
 userId int, 
 name varchar(30), 
 operation varchar(30), 
 actionDate DATE
) dbpartition by hash(userId) tbpartition by WEEK(actionDate) tbpartitions 7;

查看該邏輯表的節點拓撲，可以看出在每個分庫都建立了7張分表（一周7天）。

show topology from user_log;
+------+------------------------------------------------------------------+------------+
| ID   | GROUP_NAME                                                       | TABLE_NAME |
+------+------------------------------------------------------------------+------------+
|    0 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log_0 |
|    1 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log_1 |
|    2 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log_2 |
|    3 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log_3 |
|    4 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log_4 |
|    5 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log_5 |
|    6 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log_6 |
|    7 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log_0 |
|    8 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log_1 |
|    9 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log_2 |
|   10 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log_3 |
|   11 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log_4 |
|   12 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log_5 |
|   13 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log_6 |
...
|   49 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log_0 |
|   50 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log_1 |
|   51 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log_2 |
|   52 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log_3 |
|   53 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log_4 |
|   54 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log_5 |
|   55 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log_6 |
+------+------------------------------------------------------------------+------------+
56 rows in set (0.01 sec)

說明由於返回結果較長，這裡用...做了省略處理。

查看該邏輯表的拆分規則，可以看出分庫的拆分方式為雜湊，分庫的拆分鍵為userId，分表的拆分方式為按照時間函數WEEK進行拆分，分表的拆分鍵為actionDate。

show rule from user_log;
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
| ID   | TABLE_NAME | BROADCAST | DB_PARTITION_KEY | DB_PARTITION_POLICY | DB_PARTITION_COUNT | TB_PARTITION_KEY | TB_PARTITION_POLICY | TB_PARTITION_COUNT |
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
|    0 | user_log   |         0 | userId           | hash                | 8                  | actionDate       | week                | 7                  |
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
1 row in set (0.00 sec)

查看給定分庫鍵和分表鍵參數時， SQL被路由到哪個物理分庫和該物理分庫下的哪張物理表。

建一張表，既分庫又分表，分庫方式為根據userId列雜湊，分表方式為根據actionDate列，按照一年12個月進行拆分（MM(actionDate)計算的是MONTH_OF_YEAR）。

比如actionDate列的值是2017-02-27，MM(actionDate)算出的值是02，該條記錄就會被儲存到02（02 % 12 = 02）這張分表（位於某個分庫，具體的表名是 user_log_02）。比如actionDate列的值是2016-12-27，MM(actionDate)算出的值是12，該條記錄就會被儲存到00（12 % 12 = 00）這張分表（位於某個分庫，具體的表名是 user_log_00）。

CREATE TABLE user_log2(
 userId int, 
 name varchar(30), 
 operation varchar(30), 
 actionDate DATE
) dbpartition by hash(userId) tbpartition by MM(actionDate) tbpartitions 12;

查看該邏輯表的節點拓撲，可以看出在每個分庫都建立了12張分表（1年有12個月）。

show topology from user_log2;
+------+------------------------------------------------------------------+--------------+
| ID   | GROUP_NAME                                                       | TABLE_NAME   |
+------+------------------------------------------------------------------+--------------+
|    0 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_00 |
|    1 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_01 |
|    2 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_02 |
|    3 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_03 |
|    4 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_04 |
|    5 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_05 |
|    6 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_06 |
|    7 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_07 |
|    8 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_08 |
|    9 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_09 |
|   10 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_10 |
|   11 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log2_11 |
|   12 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_00 |
|   13 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_01 |
|   14 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_02 |
|   15 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_03 |
|   16 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_04 |
|   17 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_05 |
|   18 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_06 |
|   19 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_07 |
|   20 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_08 |
|   21 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_09 |
|   22 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_10 |
|   23 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0001_RDS | user_log2_11 |
...
|   84 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_00 |
|   85 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_01 |
|   86 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_02 |
|   87 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_03 |
|   88 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_04 |
|   89 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_05 |
|   90 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_06 |
|   91 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_07 |
|   92 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_08 |
|   93 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_09 |
|   94 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_10 |
|   95 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log2_11 |
+------+------------------------------------------------------------------+--------------+
96 rows in set (0.02 sec)

說明由於返回結果較長，這裡用...做了省略處理。

查看該邏輯表的拆分規則，可以看出分庫的拆分方式為雜湊，分庫的拆分鍵為userId，分表的拆分方式為按照時間函數MM進行拆分，分表的拆分鍵為actionDate。

show rule from user_log2;
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
| ID   | TABLE_NAME | BROADCAST | DB_PARTITION_KEY | DB_PARTITION_POLICY | DB_PARTITION_COUNT | TB_PARTITION_KEY | TB_PARTITION_POLICY | TB_PARTITION_COUNT |
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
|    0 | user_log2  |         0 | userId           | hash                | 8                  | actionDate       | mm                  | 12                 |
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
1 row in set (0.00 sec)

建一張表，既分庫又分表，分庫方式為根據userId列雜湊，分表方式為按照一個月31天進行拆分（函數DD(actionDate)計算的是DAY_OF_MONTH）。

比如actionDate列的值是2017-02-27，DD(actionDate)算出的值是27，該條記錄就會被儲存到27（27 % 31 = 27）這張分表（位於某個分庫，具體的表名是user_log_27）。

CREATE TABLE user_log3(
 userId int, 
 name varchar(30), 
 operation varchar(30), 
 actionDate DATE
) dbpartition by hash(userId) tbpartition by DD(actionDate) tbpartitions 31;

查看該邏輯表的節點拓撲，可以看出在每個分庫都建立了31張分表（按每個月有31天處理）。

show topology from user_log3;
+------+------------------------------------------------------------------+--------------+
| ID   | GROUP_NAME                                                       | TABLE_NAME   |
+------+------------------------------------------------------------------+--------------+
|    0 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_00 |
|    1 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_01 |
|    2 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_02 |
|    3 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_03 |
|    4 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_04 |
|    5 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_05 |
|    6 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_06 |
|    7 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_07 |
|    8 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_08 |
|    9 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_09 |
|   10 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_10 |
|   11 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_11 |
|   12 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_12 |
|   13 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_13 |
|   14 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_14 |
|   15 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_15 |
|   16 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_16 |
|   17 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_17 |
|   18 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_18 |
|   19 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_19 |
|   20 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_20 |
|   21 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_21 |
|   22 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_22 |
|   23 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_23 |
|   24 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_24 |
|   25 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_25 |
|   26 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_26 |
|   27 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_27 |
|   28 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_28 |
|   29 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_29 |
|   30 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log3_30 |
...
|  237 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_20 |
|  238 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_21 |
|  239 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_22 |
|  240 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_23 |
|  241 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_24 |
|  242 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_25 |
|  243 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_26 |
|  244 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_27 |
|  245 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_28 |
|  246 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_29 |
|  247 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log3_30 |
+------+------------------------------------------------------------------+--------------+
248 rows in set (0.01 sec)

說明由於返回的結果較長，這裡用...做了省略處理。

查看該邏輯表的拆分規則，可以看出分庫的拆分方式為雜湊，分庫的拆分鍵為userId，分表的拆分方式為按照時間函數DD進行拆分，分表的拆分鍵為actionDate。

show rule from user_log3;
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
| ID   | TABLE_NAME | BROADCAST | DB_PARTITION_KEY | DB_PARTITION_POLICY | DB_PARTITION_COUNT | TB_PARTITION_KEY | TB_PARTITION_POLICY | TB_PARTITION_COUNT |
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
|    0 | user_log3  |         0 | userId           | hash                | 8                  | actionDate       | dd                  | 31                 |
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
1 row in set (0.01 sec)

建一張表，既分庫又分表，分庫方式為根據userId列雜湊，分表方式為按照一年365天進行拆分，路由到365張物理表（MMDD(actionDate) tbpartitions 365計算的是DAY_OF_YEAR % 365。

比如actionDate列的值是2017-02-27，MMDD(actionDate)算出的值是58，該條記錄就會被儲存到58這張分表（位於某個分庫，具體的表名是user_log_58）。

CREATE TABLE user_log4(
 userId int, 
 name varchar(30), 
 operation varchar(30), 
 actionDate DATE
) dbpartition by hash(userId) tbpartition by MMDD(actionDate) tbpartitions 365;

查看該邏輯表的節點拓撲，可以看出在每個分庫都建立了365張分表（按每年有365天處理）。

show topology from user_log4;
+------+------------------------------------------------------------------+---------------+
| ID   | GROUP_NAME                                                       | TABLE_NAME   |
+------+------------------------------------------------------------------+---------------+
...
| 2896 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_341 |
| 2897 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_342 |
| 2898 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_343 |
| 2899 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_344 |
| 2900 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_345 |
| 2901 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_346 |
| 2902 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_347 |
| 2903 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_348 |
| 2904 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_349 |
| 2905 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_350 |
| 2906 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_351 |
| 2907 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_352 |
| 2908 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_353 |
| 2909 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_354 |
| 2910 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_355 |
| 2911 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_356 |
| 2912 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_357 |
| 2913 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_358 |
| 2914 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_359 |
| 2915 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_360 |
| 2916 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_361 |
| 2917 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_362 |
| 2918 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_363 |
| 2919 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log4_364 |
+------+------------------------------------------------------------------+---------------+
2920 rows in set (0.07 sec)

說明由於返回的結果較長，這裡用...做了省略處理。

查看該邏輯表的拆分規則，可以看出分庫的拆分方式為雜湊，分庫的拆分鍵為userId，分表的拆分方式為按照時間函數MMDD進行拆分，分表的拆分鍵為actionDate。

show rule from user_log4;
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
| ID   | TABLE_NAME | BROADCAST | DB_PARTITION_KEY | DB_PARTITION_POLICY | DB_PARTITION_COUNT | TB_PARTITION_KEY | TB_PARTITION_POLICY | TB_PARTITION_COUNT |
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
|    0 | user_log4  |         0 | userId           | hash                | 8                  | actionDate       | mmdd                | 365                |
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
1 row in set (0.02 sec)

建一張表，既分庫又分表，分庫方式為根據userId列雜湊，分表方式為按照一年365天進行拆分，路由到10張物理表（MMDD(actionDate) tbpartitions 10計算的是DAY_OF_YEAR % 10。

CREATE TABLE user_log5(
 userId int, 
 name varchar(30), 
 operation varchar(30), 
 actionDate DATE
) dbpartition by hash(userId) tbpartition by MMDD(actionDate) tbpartitions 10;

查看該邏輯表的節點拓撲，可以看出在每個分庫都建立了10張分表（按照一年365天進行拆分，路由到10張物理表）。

show topology from user_log5;
+------+------------------------------------------------------------------+--------------+
| ID   | GROUP_NAME                                                       | TABLE_NAME   |
+------+------------------------------------------------------------------+--------------+
|    0 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log5_00 |
|    1 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log5_01 |
|    2 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log5_02 |
|    3 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log5_03 |
|    4 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log5_04 |
|    5 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log5_05 |
|    6 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log5_06 |
|    7 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log5_07 |
|    8 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log5_08 |
|    9 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0000_RDS | user_log5_09 |
...
|   70 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log5_00 |
|   71 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log5_01 |
|   72 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log5_02 |
|   73 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log5_03 |
|   74 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log5_04 |
|   75 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log5_05 |
|   76 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log5_06 |
|   77 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log5_07 |
|   78 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log5_08 |
|   79 | SANGUAN_TEST_123_1488766060743ACTJSANGUAN_TEST_123_WVVP_0007_RDS | user_log5_09 |
+------+------------------------------------------------------------------+--------------+
80 rows in set (0.02 sec)

說明由於返回的結果較長，這裡用...做了省略處理。

查看該邏輯表的拆分規則，可以看出分庫的拆分方式為雜湊，分庫的拆分鍵為userId，分表的拆分方式為按照時間函數 MMDD進行拆分，路由到10張物理表，分表的拆分鍵為actionDate。

show rule from user_log5;
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
| ID   | TABLE_NAME | BROADCAST | DB_PARTITION_KEY | DB_PARTITION_POLICY | DB_PARTITION_COUNT | TB_PARTITION_KEY | TB_PARTITION_POLICY | TB_PARTITION_COUNT |
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
|    0 | user_log5  |         0 | userId           | hash                | 8                  | actionDate       | mmdd                | 10                 |
+------+------------+-----------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+
1 row in set (0.01 sec)

其他MySQL建表屬性

您在分庫分表的同時還可以指定其他的MySQL建表屬性，例如：

CREATE TABLE multi_db_multi_tbl(
  id bigint not null auto_increment, 
  name varchar(30), 
  primary key(id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 dbpartition by hash(id) tbpartition by hash(id) tbpartitions 3;

全域二級索引

說明以下樣本均假設已經建好的分庫數為8。

定義全域二級索引

樣本

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只分庫不分表，分庫的拆分方式為按照order_id列進行雜湊。
索引表：g_i_seller只分庫不分表，分庫的拆分方式為按照seller_id列進行雜湊，未指定覆蓋列。
索引定義子句：GLOBAL INDEX `g_i_seller`(`seller_id`) dbpartition by hash(`seller_id`)。

通過SHOW INDEX查看索引資訊，包含拆分鍵order_id上的局部索引，和seller_id、id、order_id上的GSI，其中seller_id為索引表的拆分鍵，id和order_id為預設的覆蓋列（主鍵和主表的拆分鍵）。

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 |               |
+---------+------------+-------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+----------+---------------+

通過SHOW GLOBAL INDEX可以單獨查看GSI資訊。詳細說明請參見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 |
+--------+---------+------------+------------+-------------+----------------+------------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+--------+

查看索引表的結構，索引表包含主表的主鍵、分庫分表鍵和預設的覆蓋列，主鍵列去除了AUTO_INCREMENT屬性，並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`) |
+------------+-----------------------------------------------------------+

定義全域唯一索引

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 只分庫不分表，分庫的拆分方式為按照order_id列進行雜湊。
索引表：g_i_buyer 只分庫且分表，分庫和分表的拆分方式均為按照buyer_id列進行雜湊，覆蓋列包含 seller_id和order_snapshot。
索引定義子句：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。

通過SHOW INDEX 查看索引資訊，包含拆分鍵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為索引表的拆分鍵，id和order_id 為預設的覆蓋列（主鍵和主表的拆分鍵），seller_id和order_snapshot為顯示指定的覆蓋列。

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 |               |
+--------------+------------+-------------------------+--------------+----------------+-----------+-------------+----------+--------+------+------------+----------+---------------+

通過SHOW GLOBAL INDEX可以單獨查看GSI資訊。詳細說明請參見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 |
+--------+---------+------------+-----------+-------------+-----------------------------------------+------------+------------------+---------------------+--------------------+------------------+---------------------+--------------------+--------+

查看索引表的結構，索引表包含主表的主鍵、分庫分表鍵、預設覆蓋列和GSI定義中指定的覆蓋列，主鍵列去除了AUTO_INCREMENT屬性，並且去除了主表中局部索引，全域唯一索引預設會建立一份資料表來實現全域的唯一性支援。

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 |
+-----------+--------------------------------------------------------------------------------------------------------+