User guide

Note
Although the console displays this information in one field, it is two parameters in the Amazon
Redshift API: ClusterVersion and ClusterRevisionNumber. For more information, go to
Cluster in the Amazon Redshift API Reference.
Amazon Redshift provides a setting, Allow Version Upgrade, to specify whether to automatically upgrade
the Amazon Redshift engine in your cluster if a new version of the engine becomes available.This setting
does not affect the database version upgrades, which are applied during the maintenance window that
you specify for your cluster. Amazon Redshift engine upgrades are major version upgrades, and Amazon
Redshift database upgrades are minor version upgrades.You can disable automatic version upgrades
for major versions only. For more information about maintenance windows for minor version upgrades,
see Maintenance Windows (p. 10).
About Clusters and Nodes
An Amazon Redshift cluster consists of nodes. There are two types of nodes: dense storage and dense
compute.The dense storage node types are recommended for substantial data storage needs, while
dense compute node types are optimized for performance-intensive workloads.
Each node type offers different sizes and limits to help you scale your cluster appropriately. The node
size determines the storage capacity, memory, CPU, and price of each node in the cluster. The node
limit determines how many nodes are available to the cluster. Initially, there is a limit of 16 nodes per
account in each region; to have this limit increased, fill out the Node Limit Increase Form.
Some node sizes allow single-node clusters, while other node sizes require multi-node clusters. Each
cluster has a leader node and a compute node. If you have a single-node cluster, the node is shared for
leader and compute node functionality. If you have a multi-node cluster, the leader node is separate from
the compute node or nodes.
A leader node receives queries from client applications, parses the queries and develops execution plans,
which are an ordered set of steps to process these queries.The leader node then coordinates the parallel
execution of these plans with the compute nodes, aggregates the intermediate results from these nodes
and finally returns the results back to the client applications.
Compute nodes execute the steps specified in the execution plans and transmit data among themselves
to serve these queries. The intermediate results are sent back to the leader node for aggregation before
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Amazon Redshift Management Guide
About Clusters and Nodes