system.clusters

Contains information about clusters available in the config file and the servers in them.

Columns:

cluster (String) — The cluster name.
shard_num (UInt32) — The shard number in the cluster, starting from 1. May change due to cluster modification.
shard_name (String) — The name of the shard in the cluster.
shard_weight (UInt32) — The relative weight of the shard when writing data.
replica_num (UInt32) — The replica number in the shard, starting from 1.
host_name (String) — The host name, as specified in the config.
host_address (String) — The host IP address obtained from DNS.
port (UInt16) — The port to use for connecting to the server.
is_local (UInt8) — Flag that indicates whether the host is local.
user (String) — The name of the user for connecting to the server.
default_database (String) — The default database name.
errors_count (UInt32) — The number of times this host failed to reach replica.
slowdowns_count (UInt32) — The number of slowdowns that led to changing replica when establishing a connection with hedged requests.
estimated_recovery_time (UInt32) — Seconds remaining until the replica error count is zeroed, and it is considered to be back to normal.
database_shard_name (String) — The name of the Replicated database shard (for clusters that belong to a Replicated database).
database_replica_name (String) — The name of the Replicated database replica (for clusters that belong to a Replicated database).
is_active (Nullable(UInt8)) — The status of the Replicated database replica (for clusters that belong to a Replicated database): 1 means "replica is online", 0 means "replica is offline", NULL means "unknown".
name (String) - An alias to cluster.

Example

Query:

Result:

See Also