A read pool is managed as a single entity to reduce your operational burden. The pool represents a homogeneous set of nodes; whenever you make any configuration change such as updating database flags, the VM type, or other parameters, the change is automatically applied to all nodes in the pool. You can also scale out and in by adding or removing nodes from the pool at any time in response to changes in the workload. Since all queries flow through the read endpoint’s load balancer, you don’t need to reconfigure your applications, even as the nodes in the pool are being updated, added, or removed.
Easier scaling with read pool autoscaling
Read pools truly shine in scenarios with variable workloads. With the general availability of autoscaling for Cloud SQL read pools, managing these fluctuations is even easier.
Key benefits of read pool autoscaling:
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Manage traffic spikes automatically: Maintain application responsiveness during peak demand as the pool dynamically scales up to 20 nodes based on database connections or CPU usage.
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Simplify operations: Because autoscaling is integrated with a single read endpoint, your applications stay connected to the same address even as underlying nodes are adjusted.
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Optimize costs: Pay only for the resources you actually use by automatically scaling in during low-traffic periods, preventing the expense of over-provisioning.
How Cloud SQL improves availability with read pools
Engineered for mission-critical reliability, Cloud SQL read pools provide the foundation for your high-availability read workloads. By maintaining at least two nodes, your read pool is backed by a 99.99% availability SLA, which includes coverage for maintenance downtime. To do this, Cloud SQL intelligently manages your environment in the following ways:
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When you add nodes to a read pool, existing connections continue without interruption on the preexisting nodes. New connections may be directed to the newly added nodes and the load shifts to be evenly balanced across the nodes as pre-existing connections finish their work.
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For read pools containing two or more nodes, when you modify the VM type or database flags, or perform most other configuration updates, the read pool is updated with near-zero downtime.
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As for any other Cloud SQL instance, Cloud SQL automatically detects and repairs issues with the underlying hardware for your read pool instances. Whenever a node is found to be unhealthy, it is removed from the load balancer rotation and a new node is created to replace it.
Enabling and using read pools with autoscaling
Read pools excel in environments with highly variable workloads. With Cloud SQL autoscaling, you can define minimum and maximum node counts while setting targets for key metrics like CPU utilization or database connections.
