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SHOW CLUSTERS

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.

quickstart cluster

A cluster named quickstart with a size of 100cc and a replication factor of 1 will be pre-installed in every environment. You can modify or drop this cluster at any time.

NOTE: The default value for the cluster session parameter is quickstart. If the quickstart cluster is dropped, you must run SET cluster to choose a valid cluster in order to run SELECT queries. A superuser (i.e. Organization Admin) can also run ALTER SYSTEM SET cluster to change the default value.

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.

To take advantage of these indexes, Materialize will automatically re-route SHOW commands and queries using system catalog objects to the mz_introspection system cluster. You can disable this behavior in your session via the auto_route_introspection_queries configuration parameter.

The following characteristics apply to the mz_introspection cluster:

  • You are not billed for this cluster.
  • You cannot create objects in this cluster.
  • You cannot drop this cluster.
  • You can run SELECT or SUBSCRIBE statements against system catalog objects on this cluster. This includes queries with joins, as long as the query depends only on objects in the system catalog.

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 objects in this cluster.
  • You cannot drop this cluster.
  • You cannot run SELECT or SUBSCRIBE on this cluster.

mz_probe system cluster

A system cluster named mz_probe will be pre-installed in every environment. This cluster is used for uptiming monitoring.

The following characteristics apply to the mz_probe cluster:

  • You are not billed for this cluster.
  • You cannot create objects in this cluster.
  • You cannot drop this cluster.
  • You cannot run SELECT or SUBSCRIBE on this cluster.

mz_support system cluster

A system cluster named mz_support will be pre-installed in every environment. This cluster is used for support to perform one-off debugging and validation.

The following characteristics apply to the mz_support cluster:

  • You are not billed for this cluster.
  • You cannot create objects in this cluster.
  • You cannot drop this cluster.
  • You cannot run SELECT or SUBSCRIBE on this cluster.

Examples

SET CLUSTER = mz_introspection;

SHOW CLUSTERS;

       name                  replicas
--------------------- | ------------------
 default              |  r1 (25cc)
 auction_house        |  r1 (25cc)
 mz_introspection     |  r1 (50cc)
 mz_system            |  r1 (50cc)
 mz_probe             |  r1 (mz_probe)
 mz_support           |

SHOW CLUSTERS LIKE 'auction_%';

      name                  replicas
--------------------- | ------------------
 auction_house        |  r1 (25cc)
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