mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-15 10:52:30 +00:00
75 lines
3.2 KiB
Markdown
75 lines
3.2 KiB
Markdown
---
|
|
slug: /en/operations/system-tables/clusters
|
|
---
|
|
# clusters
|
|
|
|
Contains information about clusters available in the config file and the servers in them.
|
|
|
|
Columns:
|
|
|
|
- `cluster` ([String](../../sql-reference/data-types/string.md)) — The cluster name.
|
|
- `shard_num` ([UInt32](../../sql-reference/data-types/int-uint.md)) — The shard number in the cluster, starting from 1.
|
|
- `shard_weight` ([UInt32](../../sql-reference/data-types/int-uint.md)) — The relative weight of the shard when writing data.
|
|
- `replica_num` ([UInt32](../../sql-reference/data-types/int-uint.md)) — The replica number in the shard, starting from 1.
|
|
- `host_name` ([String](../../sql-reference/data-types/string.md)) — The host name, as specified in the config.
|
|
- `host_address` ([String](../../sql-reference/data-types/string.md)) — The host IP address obtained from DNS.
|
|
- `port` ([UInt16](../../sql-reference/data-types/int-uint.md)) — The port to use for connecting to the server.
|
|
- `is_local` ([UInt8](../../sql-reference/data-types/int-uint.md)) — Flag that indicates whether the host is local.
|
|
- `user` ([String](../../sql-reference/data-types/string.md)) — The name of the user for connecting to the server.
|
|
- `default_database` ([String](../../sql-reference/data-types/string.md)) — The default database name.
|
|
- `errors_count` ([UInt32](../../sql-reference/data-types/int-uint.md)) — The number of times this host failed to reach replica.
|
|
- `slowdowns_count` ([UInt32](../../sql-reference/data-types/int-uint.md)) — The number of slowdowns that led to changing replica when establishing a connection with hedged requests.
|
|
- `estimated_recovery_time` ([UInt32](../../sql-reference/data-types/int-uint.md)) — Seconds remaining until the replica error count is zeroed and it is considered to be back to normal.
|
|
|
|
**Example**
|
|
|
|
Query:
|
|
|
|
```sql
|
|
SELECT * FROM system.clusters LIMIT 2 FORMAT Vertical;
|
|
```
|
|
|
|
Result:
|
|
|
|
```text
|
|
Row 1:
|
|
──────
|
|
cluster: test_cluster_two_shards
|
|
shard_num: 1
|
|
shard_weight: 1
|
|
replica_num: 1
|
|
host_name: 127.0.0.1
|
|
host_address: 127.0.0.1
|
|
port: 9000
|
|
is_local: 1
|
|
user: default
|
|
default_database:
|
|
errors_count: 0
|
|
slowdowns_count: 0
|
|
estimated_recovery_time: 0
|
|
|
|
Row 2:
|
|
──────
|
|
cluster: test_cluster_two_shards
|
|
shard_num: 2
|
|
shard_weight: 1
|
|
replica_num: 1
|
|
host_name: 127.0.0.2
|
|
host_address: 127.0.0.2
|
|
port: 9000
|
|
is_local: 0
|
|
user: default
|
|
default_database:
|
|
errors_count: 0
|
|
slowdowns_count: 0
|
|
estimated_recovery_time: 0
|
|
```
|
|
|
|
**See Also**
|
|
|
|
- [Table engine Distributed](../../engines/table-engines/special/distributed.md)
|
|
- [distributed_replica_error_cap setting](../../operations/settings/settings.md#settings-distributed_replica_error_cap)
|
|
- [distributed_replica_error_half_life setting](../../operations/settings/settings.md#settings-distributed_replica_error_half_life)
|
|
|
|
[Original article](https://clickhouse.com/docs/en/operations/system-tables/clusters) <!--hide-->
|