This document provides an introduction to MySQL master-slave replication. It defines replication as copying data from a master database server to one or more slave servers. The key concepts of master and slave are explained. Advantages of replication include scaling out solutions, increasing data security, enabling analytics, and distributing data over long distances. Event-based and GTID-based replication methods are described. The document also demonstrates setting up master-slave replication between two AWS MySQL instances and provides guidance on when replication is best used, such as for systems with many reads and few writes.

1. Intro to MySQL Master
Slave Replication
Satej Kumar Sahu
Mindfire Solutions

2. Contents
• What is Replication?
• Concept of Master and Slave
• Advantages of Replication
• Methods of Replication
• How event based replication works?
• Demo setup of master slave replication in MySQL
• Code/config setup from the start for allowing app level support for master-slave setups later
• Scenarios best for this setup/strategy
• Conclusion
• References

3. What is Replication?
• Replication enables data from one MySQL
database server (the master) to be copied to one or
more MySQL database servers (the slaves).
• By default asynchronous.

4. Concept of Master and Slave

5. Advantages of Replication
• Scale-out solutions
• Data security
• Analytics
• Long-distance data distribution

6. Methods of Replication
• Traditional method based on replicating events
from the master's binary log, and requires the log
files and positions in them to be synchronized
between master and slave.
- Types of events: Row based (default) or statement
based or mixed type.
• Newer method based on global transaction
identifiers (GTIDs) which is transactional.

7. How event based
Replication works?

8. Demo setup of master slave
replication in MySQL
• Two AWS instances with port 3306 open for mysql
on master instance.

9. Code/config setup from the start for
allowing app level support for master-slave
setups later
• Database access layer code should have been properly abstracted/modularized
• safe_writer_connect()
safe_reader_connect()
safe_reader_statement()
safe_writer_statement()
• Important thing is to have a unified interface for connecting for reads, connecting for
writes, doing a read, and doing a write.
• May be a painful and scary process at first. The code is much easier to maintain, and
adding troubleshooting options is trivial. You need modify only one or two functions;
for example, to log how long each statement took, or which statement among those
issued gave you an error.
• Also, you can create a user for write only and read only privileges to connect to master
and slave for added separation of concern layer.

10. Scenarios best for this
setup/strategy
• Most of the cases you would not need it. A good designed, optimised, normalized
database would not require it normally.
• MySQL replication is most beneficial for a system that processes frequent reads and
infrequent or low number of writes/updates.
• Answering the following questions should help you decide whether and by how much
replication will improve the performance of your system
- read/write ratio on your system?
- How much more write load can one server handle if you reduce the reads?
- For how many slaves do you have bandwidth available on your network?
• Examples:
- Ecommerce sites
- Newspaper sites
- Online library sites
- Blogging sites
• Browsing happens much in comparison to writes.

11. Conclusion
• In most of the case, given good database design
and optimisations and use of indexes, you would
not need replication in most of the cases.
• But if you need to scale out due to large number of
reads, you should go for it :)

12. References
• http://dev.mysql.com/doc/refman/5.7/en/replication.html
• https://www.percona.com/blog/2013/01/09/how-does-
mysql-replication-really-work/
• https://dev.mysql.com/doc/refman/5.7/en/faqs-
replication.html
• https://dev.mysql.com/doc/refman/5.7/en/faqs-
replication.html#faq-replication-replication-how-benefits-
me

13. any?

14. Thank You :)