SHOW CLUSTERS

NOTE! For improved performance, execute this command in the mz_introspection cluster. To switch clusters, use SET CLUSTER = mz_introspection;.

SHOW CLUSTERS lists the clusters configured in Materialize.

Syntax

SHOW CLUSTERS LIKE pattern WHERE expr

Pre-installed clusters

When you enable a Materialize region, several clusters that are used to improve the user experience, as well as support system administration tasks, will be pre-installed.

default cluster

A cluster named default with a single xsmall replica named r1 will be pre-installed in every environment. You can modify or drop this cluster or its replicas at any time.

NOTE: The default value for the cluster session parameter is default. If the default cluster is dropped, you must run SET cluster to choose a valid cluster in order to run SELECT queries.

mz_introspection system cluster

A system cluster named mz_introspection will be pre-installed in every environment. This cluster has several indexes installed to speed up common introspection queries, like SHOW commands and queries using the system catalog. It is recommended to switch to the mz_introspection cluster for improved performance when executing these statements.

The following characteristics apply to the mz_introspection cluster:

  • You are not billed for this cluster.
  • You cannot create indexes or materialized views on this cluster.
  • You cannot drop this cluster.
  • You can run SELECT or SUBSCRIBE statements on this cluster.

mz_system system cluster

A system cluster named mz_system will be pre-installed in every environment. This cluster is used for various internal system monitoring tasks.

The following characteristics apply to the mz_system cluster:

  • You are not billed for this cluster.
  • You cannot create indexes or materialized views on this cluster.
  • You cannot drop this cluster.
  • You cannot run SELECT or SUBSCRIBE on this cluster.

Examples

SET CLUSTER = mz_introspection;

SHOW CLUSTERS;
       name
---------------------
 default
 auction_house
 mz_introspection
 mz_system
SHOW CLUSTERS LIKE 'auction_%';
       name
---------------------
 auction_house
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