https://github.com/emahtab/mysql-master-master-replication
A demo showing bidirectional database replication between two MySQL master.
https://github.com/emahtab/mysql-master-master-replication
database-replication master-master-replication mysql
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A demo showing bidirectional database replication between two MySQL master.
- Host: GitHub
- URL: https://github.com/emahtab/mysql-master-master-replication
- Owner: eMahtab
- Created: 2024-12-06T12:46:28.000Z (7 months ago)
- Default Branch: main
- Last Pushed: 2024-12-06T16:54:27.000Z (7 months ago)
- Last Synced: 2025-02-02T03:19:08.057Z (5 months ago)
- Topics: database-replication, master-master-replication, mysql
- Homepage:
- Size: 896 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# MySQL Bidirectional database replication between two master (master-master-replication)
This demo is a variation of https://github.com/eMahtab/mysql-master-slave-replication , where we had setup Master Slave replication from a single mysql master to a single mysql slave/replica.
In this demo we setup two MySQL instances (e.g. mysql-master-1 and mysql-master-2), both working as master.
**mysql-master-1 replicates its data to mysql-master-2 and mysql-master-2 replicates its data to mysql-master-1.**
### !!! Prerequisite : You would need Docker installed on your system to follow along this demo.
We would run both mysql-master-1 and mysql-master-2 as docker containers, using docker compose.
## Step 1 : Create the Docker compose file and execute docker compose up
Below docker-compose-master-master.yml declares two services, named as mysql_master_1 and mysql_master_2 (in docker compose file actual containers are named as mysql-master-1 and mysql-master-2). We are using **mysql:8.0** as the docker image, and declare root user password as `toor` and create a test database.
**Make sure docker engine is running on your host machine before running the `docker compose -f docker-compose-master-master.yml up` command.**
```yml
---
version: "2"
services:
mysql_master_1:
image: mysql:8.0
container_name: mysql-master-1
volumes:
- mysql-master-1-volume:/tmp
command:
[
"mysqld",
"--datadir=/tmp/master1/data",
"--log-bin=bin.log",
"--server-id=1"
]
environment:
&mysql-default-environment
MYSQL_ROOT_PASSWORD: toor
MYSQL_DATABASE: test
MYSQL_USER: test_user
MYSQL_PASSWORD: insecure
ports:
- "3308:3306"
mysql_master_2:
image: mysql:8.0
container_name: mysql-master-2
volumes:
- mysql-master-2-volume:/tmp
command:
[
"mysqld",
"--datadir=/tmp/master2/data",
"--log-bin=bin.log",
"--server-id=2"
]
environment: *mysql-default-environment
ports:
- "3309:3306"
volumes:
mysql-master-1-volume:
mysql-master-2-volume:
```
## Step 2 : Create Replication user on both the MySQL instances with REPLICATION SLAVE privilege
Next we need to create a replication user on both the MySQL instances `(mysql-master-1 and mysql-master-2)` and grant that user `REPLICATION SLAVE` privilege.
To do this, we first open the bash shell on each MySQL instance **`docker exec -it mysql-master-1 bash`** and connect to mysql **`mysql -uroot -ptoor`** running on the instance, then execute below mysql commands.
```sql
CREATE USER 'replicator'@'%' IDENTIFIED BY 'rotacilper';
GRANT REPLICATION SLAVE ON *.* TO 'replicator'@'%';
FLUSH PRIVILEGES;
```
Here we create a replication user called `replicator` with password `rotacilper` and grant this user **`REPLICATION SLAVE`** privilege, and finally flush privileges.
## Step 3 : Execute SHOW MASTER STATUS on both the MySQL instances
Get the master status, execute the command **`SHOW MASTER STATUS;`** on both the MySQL instances to find the Binlog file and position.
## Step 4 : Execute `CHANGE MASTER TO` and `START SLAVE;` command on both the MySQL instances
Next we need to execute **`CHANGE MASTER TO`** and `START SLAVE;` command on both the MySQL instances. Connect to each MySQL instance and execute below command, **_don't forget to update MASTER_LOG_FILE and MASTER_LOG_POS values_** which you got from executing SHOW MASTER STATUS command.
### On mysql-master-1
Update **_MASTER_LOG_FILE and MASTER_LOG_POS_** and then execute this on MySQL instance running on mysql-master-1 docker container
```sql
CHANGE MASTER TO
MASTER_HOST='mysql_master_2',
MASTER_PORT=3306,
MASTER_USER='replicator',
MASTER_PASSWORD='rotacilper',
MASTER_LOG_FILE='[log_file_name_from_mysql-master-2]',
MASTER_LOG_POS=[log_position_from_mysql-master-2],
GET_MASTER_PUBLIC_KEY=1;
```
and then
```sql
START SLAVE;
```
### On mysql-master-2
Update **_MASTER_LOG_FILE and MASTER_LOG_POS_** and then execute this on MySQL instance running on mysql-master-2 docker container
```sql
CHANGE MASTER TO
MASTER_HOST='mysql_master_1',
MASTER_PORT=3306,
MASTER_USER='replicator',
MASTER_PASSWORD='rotacilper',
MASTER_LOG_FILE='[log_file_name_from_mysql-master-1]',
MASTER_LOG_POS=[log_position_from_mysql-master-1],
GET_MASTER_PUBLIC_KEY=1;
```
and then
```sql
START SLAVE;
```
## Step 5 : Insert Records on mysql-master-1 and see Replication in action
By performing the steps 1 to 4, we have set the replication from mysql-master-1 to mysql-master-2 and vice versa, now whatever changes are done on any one of the MySQL instance will be replicated to other MySQL instance automatically.
We create a `users` table under test database on `mysql-master-1` and insert 20 records in `users` table
```sql
USE test
CREATE TABLE users (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255) NOT NULL);
INSERT INTO users (name)
VALUES
('Alice'),
('Bob'),
('Charlie'),
('David'),
('Eve'),
('Frank'),
('Grace'),
('Hannah'),
('Ivy'),
('Jack'),
('Karen'),
('Liam'),
('Mia'),
('Noah'),
('Olivia'),
('Paul'),
('Quincy'),
('Rachel'),
('Sophia'),
('Thomas');
```
Records are replicated on **_mysql-master-2_**
## Step 5a : Create and execute a MySQL procedure on mysql-master-1 and see Replication in action
```sql
DELIMITER $$
```
Next we create a procedure `insert_users` which inserts 10,000 records in `users` table
```sql
CREATE PROCEDURE insert_users()
BEGIN
DECLARE i INT DEFAULT 1;
WHILE i <= 10000 DO
INSERT INTO users (name) VALUES (CONCAT('User_', i));
SET i = i + 1;
END WHILE;
END$$
```
```sql
DELIMITER ;
```
### And then execute the procedure
```sql
CALL insert_users();
```
### Below screenshot shows replication in progress and after some time all 10,000 records are replicated on mysql-master-2
## Step 6 : Testing the replication in opposite direction, from mysql-master-2 to mysql-master-1 (Bidirectional data replication)
We insert 2 records in `users` table on mysql-master-2 , and those 2 records are replicated to mysql-master-1, as shown in screenshot below.
### Step 6a : Testing the replication in opposite direction, from mysql-master-2 to mysql-master-1 (Bidirectional data replication)
Next we create a table `da_events` on `mysql-master-2` and insert a single record in the table.
```sql
CREATE TABLE da_events (id INT AUTO_INCREMENT PRIMARY KEY, event_type VARCHAR(200));
INSERT INTO da_events VALUES (1, 'FETCH_CATEGORY');
```
As we can see from screenshot the data is replicated on `mysql-master-1`
# References :
1. https://github.com/eMahtab/mysql-master-slave-replication