Jul
16
2018
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InnoDB Cluster in a Nutshell: Part 2 MySQL Router

MySQL Router MySQL Cluster

MySQL Router MySQL ClusterMySQL InnoDB Cluster is an Oracle High Availability solution that can be easily installed over MySQL to provide high availability with multi-master capabilities and automatic failover. In the previous post we presented the first component of InnoDB Cluster, group replication. Now we will go through the second component, MySQL Router.  We will address MySQL Shell in a final instalment of this three-part series. By then, you should have a good overview of the features offeed by MySQL InnoDB Cluster.

MySQL Router

This component is responsible for distributing the traffic between members of the cluster. It is a proxy-like solution to hide cluster topology from applications, so applications don’t need to know which member of a cluster is the primary node and which are secondaries.

The tool is capable of performing read/write splitting by exposing different interfaces. A common setup is to have one read-write interface and one read-only interface. This is default behavior that also exposes 2 similar interfaces to use x-protocol (i.e. used for CRUD operations and async calls).

The read and write split is done using a concept of roles: Primary for writes and Secondary for read-only. This is analogous to how members of cluster are named. Additionally, each interface is exposed via a TCP port so applications only need to know the IP:port combination used for writes and the one used for reads. Then, MySQL Router will take care of connections to cluster members depending on the type of traffic to server.

MySQL Router is a very simple tool, maybe too simple as it is a layer four load balance and lacks some of the advanced features that some of it’s competitors have (e.g.. ProxySQL).

Here is a short list of the most important features of MySQL Router:

  • As mentioned, read and write split based on roles.
  • Load balancing both for reads and writes use different algorithms.
  • Configuration is stored in a configuration test file.
  • Automatically detects cluster topology by connecting and retrieving information, based on this information the router configures itself with default rules.
  • Automatically detects failing nodes and redirects traffic accordingly.

Algorithms used for routing

An important thing to mention is the routing_strategy algorithms that are available, as they are assigned by default depending on the routing mode:

  • For PRIMARY mode (i.e. writer node – or nodes): uses the first-available algorithm that picks the first writer node from a list of writes and in case of failure moves to the next in the list. If the failing node comes back to life, it’s automatically added to the list of servers and become PRIMARY again when cluster assign this status. When no writers are available then write routing is stopped
  • For read-only mode (i.e. read nodes): uses the round-robin algorithm between servers listed in the destinations variable. This mode splits read traffic between all servers in an even manner.

Additional routing_strategy algorithms :

  • next-available: similar to first-available but in this case a failing node is marked as crashed and can’t get back into the rotation.
  • round-robin-with-fallback: same as round-robin but it includes the ability in this case of using servers from the primary list (writers) to distribute the read traffic.

A sample configuration

For performance purposes it’s recommended to setup MySQL Router in the same place as the application, considering an instance per application server.

Here you can see a sample configuration file auto-generated by --bootstrap functionality:

$ cat /etc/mysqlrouter/mysqlrouter.conf
# File automatically generated during MySQL Router bootstrap
[DEFAULT]
name=system
user=mysqlrouter
keyring_path=/var/lib/mysqlrouter/keyring
master_key_path=/etc/mysqlrouter/mysqlrouter.key
connect_timeout=30
read_timeout=30
[logger]
level = INFO
[metadata_cache:percona]
router_id=4
bootstrap_server_addresses=mysql://192.168.70.4:3306,mysql://192.168.70.3:3306,mysql://192.168.70.2:3306
user=mysql_router4_56igr8pxhz0m
metadata_cluster=percona
ttl=5
[routing:percona_default_rw]
bind_address=0.0.0.0
bind_port=6446
destinations=metadata-cache://percona/default?role=PRIMARY
routing_strategy=round-robin
protocol=classic
[routing:percona_default_ro]
bind_address=0.0.0.0
bind_port=6447
destinations=metadata-cache://percona/default?role=SECONDARY
routing_strategy=round-robin
protocol=classic
[routing:percona_default_x_rw]
bind_address=0.0.0.0
bind_port=64460
destinations=metadata-cache://percona/default?role=PRIMARY
routing_strategy=round-robin
protocol=x
[routing:percona_default_x_ro]
bind_address=0.0.0.0
bind_port=64470
destinations=metadata-cache://percona/default?role=SECONDARY
routing_strategy=round-robin
protocol=x

We are almost done now, only one post left. The final post is about our third component MySQL Shell, so please keep reading.

The post InnoDB Cluster in a Nutshell: Part 2 MySQL Router appeared first on Percona Database Performance Blog.

Nov
14
2017
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Webinars on Wednesday November 15, 2017: Proxy Wars and Percona Software Update for Q4

Webinars double bill

Do you need to get to grips with MySQL proxies? Or maybe you could do with discovering the latest developments and plans for Percona’s software?

Webinars double billWell, wait no more because …

on Wednesday November 15, 2017, we bring you a webinar double bill.

Securing Your MySQLJoin Percona’s Chief Evangelist, Colin Charles as he presents “The Proxy Wars – MySQL Router, ProxySQL, MariaDB MaxScale” at 7:00 am PST / 10:00 am EST (UTC-8).

Reflecting on his past experience with MySQL proxies, Colin will provide a short review of three open source solutions. He’ll run through a comparison of MySQL Router, MariaDB MaxScale and ProxySQL and talk about the reasons for using the right tool for an application.

 

Percona Live EuropeMeanwhile, return a little later in the day at 10:00 am PST / 1:00 pm EST (UTC-8) to hear Percona CEO Peter Zaitsev discuss what’s new in Percona open source software. In “Percona Software News and Roadmap Update – Q4 2017”, Peter will talk about new features in Percona software, show some quick demos and share highlights from the Percona open source software roadmap. He will also talk about new developments in Percona commercial services and finish with a Q&A.

 

You are, of course, very welcome to register for either one or both webinars. Please register for your place soon!


Peter Zaitsev, Percona CEO and Co-Founder

Peter Zaitsev co-founded Percona and assumed the role of CEO in 2006. As one of the foremost experts on MySQL strategy and optimization, Peter leveraged both his technical vision and entrepreneurial skills to grow Percona from a two-person shop to one of the most respected open source companies in the business. With over 150 professionals in 30+ countries, Peter’s venture now serves over 3000 customers – including the “who’s who” of internet giants, large enterprises and many exciting startups. Percona was named to the Inc. 5000 in 2013, 2014, 2015 and 2016. Peter was an early employee at MySQL AB, eventually leading the company’s High Performance Group. A serial entrepreneur, Peter co-founded his first startup while attending Moscow State University, where he majored in Computer Science. Peter is a co-author of High Performance MySQL: Optimization, Backups, and Replication, one of the most popular books on MySQL performance. Peter frequently speaks as an expert lecturer at MySQL and related conferences, and regularly posts on the Percona Database Performance Blog. Fortune and DZone have both tapped Peter as a contributor, and his recent ebook Practical MySQL Performance Optimization is one of percona.com’s most popular downloads.

Colin Charles, Chief Evangelist

Colin Charles is the Chief Evangelist at Percona. He was previously on the founding team for MariaDB Server in 2009, worked in MySQL since 2005 and been a MySQL user since 2000. Before joining MySQL, he worked actively on the Fedora and OpenOffice.org projects. He’s well known within many open source communities and has spoken on the conference circuit.

 

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