Table of Contents
What is a Multi-Cluster Warehouse?
By default, a virtual warehouse is a single cluster whereas a multi-cluster warehouse is consists of multiple clusters for handling concurrent queries.
A multi-cluster warehouse can be specified by the following properties:
- Maximum number of clusters, greater than 1 (up to 10).
- Minimum number of clusters, equal to or less than the maximum (up to 10).
Moreover, multi-cluster warehouses offer identical features and capabilities as single-cluster warehouses, such as:
- Defining the size of a warehouse.
- Adjusting the size of a warehouse whenever necessary.
- Automatically suspending a warehouse if it remains inactive; it’s important to note that this feature applies to the entire multi-cluster warehouse rather than individual clusters.
- Automatically resuming a suspended warehouse when new queries are received.
Maximized vs. auto-scale
A multi-cluster warehouse can be run in below modes:
Maximized
In this mode, the value for both maximum and minimum number of clusters will be same (note that the specified value must be larger than 1). So, when the warehouse is started, all the clusters are started and maximum resources are available.
This mode is effective when large numbers of concurrent user sessions and/or queries are there and do not often change.
Auto-scale
In this mode, different values for maximum and minimum number of clusters are specified. In this mode, Snowflake starts and stops clusters as per the requirement in a dynamically managed way.
- If concurrent queries/users are increased/queued, Snowflake automatically starts additional clusters, up to the maximum number defined for the warehouse.
- Similarly, as the load on the warehouse decreases, Snowflake automatically shuts down clusters to reduce the number of running clusters.
Setting the scaling policy for a multi-cluster warehouse
To help control the credit usage for auto scale mode, snowflake provides scaling policies which can be set up.
(Ref. Snowflake Website)
For example, in SQL:
ALTER WAREHOUSE mywh SET SCALING_POLICY = 'ECONOMY';More Information : Multi-cluster warehouses | Snowflake Documentation
