How to Add Read-Only Nodes to MySQL Database Clusters
Validated on 1 Mar 2021 •
Posted on 20 Aug 2019
MySQL is an open source, object-relational database built with speed and reliability in mind. Its large and active developer community has created many third-party applications, tools, and libraries that expand MySQL’s functionality.
Read-only nodes are replicas of a cluster’s primary node located in additional geographical regions. Using read-only nodes reduces latency for users connecting from those regions.
Communication between primary and read-only nodes is SSL-encrypted and sent over the public network.
Note
Read-only nodes differ from standby nodes, which are exact copies of the primary node that are automatically moved into place in the event of a primary node failure.
Create a Read-Only Node Using the CLI
Note
To create a read-only node using doctl, you need to provide values --region and --size flags, which specify the node’s data center and its configuration (number of CPUs, amount of RAM, and hard disk space). Use the doctl databases options regions and doctl databases options slugs commands, respectively, to get a list of available values.
How to create a read-only node using the DigitalOcean CLI
To create a read-only node via the command-line, follow these steps:
Use the token to grant doctl access to your
DigitalOcean account.
doctl auth init
Finally, create a read-only node with
doctl databases replica create. The basic usage looks
like this, but you'll want to read the usage docs for more details:
To create a read-only node using the API, you need to provide values for the region and size fields, which specify the new node’s data center and its configuration (number of CPUs, amount of RAM, and hard disk space). Use the /v2/databases/options endpoint to get a list of available values.
How to create a read-only node using the DigitalOcean API
To create a read-only node using the DigitalOcean API, follow these steps:
To add a read-only node, click on the name of the cluster to go to its Overview. At the bottom of the page, click the Add a read-only node link to go to the read-only node creation page.
Select the size, which must be equal to or larger than the primary node, then select the datacenter and name the node. When you’re done, click Create a read-only node to provision the node.
Like primary nodes, you can limit access to a read-only nodes to trusted sources and access read-only nodes using a command-line client and the connection string in the node’s Overview page.