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SHOW CLUSTERS

doc/user/content/sql/show-clusters.md

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SHOW CLUSTERS lists the clusters configured in Materialize.

Syntax

sql
SHOW CLUSTERS
[LIKE <pattern> | WHERE <condition(s)>]
;
Syntax elementDescription
LIKE <pattern>If specified, only show clusters that match the pattern.
WHERE <condition(s)>If specified, only show clusters that match the condition(s).

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 25cc 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. {{< /note >}}

mz_catalog_server system cluster

A system cluster named mz_catalog_server will be pre-installed in every environment. This cluster has several indexes installed to speed up 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_catalog_server system cluster. You can disable this behavior in your session via the auto_route_catalog_queries configuration parameter.

The following characteristics apply to the mz_catalog_server 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 queries in this cluster as long as you only reference objects in the system catalog.

mz_probe system cluster

A system cluster named mz_probe will be pre-installed in every environment. This cluster is used for internal uptime 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 queries in this cluster.

mz_support system cluster

A system cluster named mz_support will be pre-installed in every environment. This cluster is used for internal support tasks.

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 queries in this cluster.

mz_system system cluster

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

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 queries in this cluster.

Examples

mzsql
SET CLUSTER = mz_catalog_server;

SHOW CLUSTERS;
nofmt
       name                  replicas
--------------------- | ------------------
 default              |  r1 (25cc)
 auction_house        |  r1 (25cc)
 mz_catalog_server    |  r1 (50cc)
 mz_system            |  r1 (50cc)
 mz_probe             |  r1 (mz_probe)
 mz_support           |
mzsql
SHOW CLUSTERS LIKE 'auction_%';
nofmt
      name                  replicas
--------------------- | ------------------
 auction_house        |  r1 (25cc)