from MySQL 8.0.30 Start ,MySQL Support in GIPK Generate invisible primary keys when running in mode . When running in this mode , For anything created without an explicit primary key InnoDB surface ,MySQL The server will automatically generate the invisible primary key (GIPK) Add to table .
GIPK Mode by sql_generate_invisible_primary_key System variable control . By default , The value of the variable is OFF, Disable GIPK Pattern ; To enable the GIPK Pattern , Please set the variable to ON.
To illustrate GIPK How patterns affect table creation , We first create two identical tables , They all have no primary key , first (table auto_0) Disabled GIPK Pattern , the second (auto_1) After enabling it , As shown below ：
mysql> SELECT @@sql_generate_invisible_primary_key; +--------------------------------------+ | @@sql_generate_invisible_primary_key | +--------------------------------------+ | 0 | +--------------------------------------+ 1 row in set (0.00 sec) mysql> CREATE TABLE auto_0 (c1 VARCHAR(50), c2 INT); Query OK, 0 rows affected (0.02 sec) mysql> SET sql_generate_invisible_primary_key=ON; Query OK, 0 rows affected (0.00 sec) mysql> SELECT @@sql_generate_invisible_primary_key; +--------------------------------------+ | @@sql_generate_invisible_primary_key | +--------------------------------------+ | 1 | +--------------------------------------+ 1 row in set (0.00 sec) mysql> CREATE TABLE auto_1 (c1 VARCHAR(50), c2 INT); Query OK, 0 rows affected (0.04 sec)
sql_generate_invisible_primary_key The setting of variables will not be copied , It will be copied applier Thread ignore . This means that replication will not generate primary keys for tables without primary keys in the primary Library .
Use show create table Command to see the difference between the above two sample tables ：
mysql> SHOW CREATE TABLE auto_0\G
*************************** 1. row ***************************
Table: auto_0
Create Table: CREATE TABLE `auto_0` (
`c1` varchar(50) DEFAULT NULL,
`c2` int DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
1 row in set (0.00 sec)
mysql> SHOW CREATE TABLE auto_1\G
*************************** 1. row ***************************
Table: auto_1
Create Table: CREATE TABLE `auto_1` (
`my_row_id` bigint unsigned NOT NULL AUTO_INCREMENT /*!80023 INVISIBLE */,
`c1` varchar(50) DEFAULT NULL,
`c2` int DEFAULT NULL,
PRIMARY KEY (`my_row_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
1 row in set (0.00 sec)because auto_1 There is no primary key ,GIPK The schema adds an invisible my_row_id Column , And as the primary key . While creating tables auto_0 When , Disabled GIPK Pattern , So no additional primary key columns are generated .
GIPK The primary key added by the mode , Column sum key Names are always my_row_id. therefore , Open the GIPK Pattern , Users cannot list names that contain my_row_id Table of , Unless the table has explicitly created a primary key .
my_row_id Columns are invisible columns , Use select * It cannot be viewed .
stay GIPK After the mode takes effect , Do not modify my_row_id, Only the status can be modified visible or invisible. such as ：
mysql> ALTER TABLE auto_1 ALTER COLUMN my_row_id SET VISIBLE;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> SHOW CREATE TABLE auto_1\G
*************************** 1. row ***************************
Table: auto_1
Create Table: CREATE TABLE `auto_1` (
`my_row_id` bigint unsigned NOT NULL AUTO_INCREMENT,
`c1` varchar(50) DEFAULT NULL,
`c2` int DEFAULT NULL,
PRIMARY KEY (`my_row_id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
1 row in set (0.00 sec)
mysql> ALTER TABLE auto_1 ALTER COLUMN my_row_id SET INVISIBLE;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> SHOW CREATE TABLE auto_1\G
*************************** 1. row ***************************
Table: auto_1
Create Table: CREATE TABLE `auto_1` (
`my_row_id` bigint unsigned NOT NULL AUTO_INCREMENT /*!80023 INVISIBLE */,
`c1` varchar(50) DEFAULT NULL,
`c2` int DEFAULT NULL,
PRIMARY KEY (`my_row_id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
1 row in set (0.00 sec)
mysql> The default is invisible .
GIPK Patterns are just for InnoDB It works .
default ,show create table、show columns、show index Can be displayed GIPK; stay information_schema.columns and information_schema.statistics It is also visible in . You can also use variables show_gipk_in_create_table_and_information_schema( The default value is on) Hide it .
mysql> SELECT @@show_gipk_in_create_table_and_information_schema;
+----------------------------------------------------+
| @@show_gipk_in_create_table_and_information_schema |
+----------------------------------------------------+
| 1 |
+----------------------------------------------------+
1 row in set (0.00 sec)
mysql> SELECT COLUMN_NAME, ORDINAL_POSITION, DATA_TYPE, COLUMN_KEY
-> FROM INFORMATION_SCHEMA.COLUMNS
-> WHERE TABLE_NAME = "auto_1";
+-------------+------------------+-----------+------------+
| COLUMN_NAME | ORDINAL_POSITION | DATA_TYPE | COLUMN_KEY |
+-------------+------------------+-----------+------------+
| my_row_id | 1 | bigint | PRI |
| c1 | 2 | varchar | |
| c2 | 3 | int | |
+-------------+------------------+-----------+------------+
3 rows in set (0.01 sec)Set to off after ：
mysql> SET show_gipk_in_create_table_and_information_schema = OFF;
Query OK, 0 rows affected (0.00 sec)
mysql> SELECT @@show_gipk_in_create_table_and_information_schema;
+----------------------------------------------------+
| @@show_gipk_in_create_table_and_information_schema |
+----------------------------------------------------+
| 0 |
+----------------------------------------------------+
1 row in set (0.00 sec)
mysql> SELECT COLUMN_NAME, ORDINAL_POSITION, DATA_TYPE, COLUMN_KEY
-> FROM INFORMATION_SCHEMA.COLUMNS
-> WHERE TABLE_NAME = "auto_1";
+-------------+------------------+-----------+------------+
| COLUMN_NAME | ORDINAL_POSITION | DATA_TYPE | COLUMN_KEY |
+-------------+------------------+-----------+------------+
| c1 | 2 | varchar | |
| c2 | 3 | int | |
+-------------+------------------+-----------+------------+
2 rows in set (0.00 sec)GIPK Mode support in row-based Under the create table ... select, In this case , Generated by this statement binlog The log contains GIPK Information , Therefore, replication will not be affected . If it is Statement-based Next , Do not support .
