ClickHouse/docs/en/operations/system-tables/distributed_ddl_queue.md

system.distributed_ddl_queue

Contains information about distributed ddl queries (ON CLUSTER queries) that were executed on a cluster.

Columns:

• entry (String) - Query id.
• host_name (String) - Hostname.
• host_address (String) - IP address that the Hostname resolves to.
• port (UInt16) - Host Port.
• status (Enum) - Stats of the query.
• cluster (String) - Cluster name.
• value (String) - Node value.
• query_start_time (Date) — Query start time.
• query_finish_time (Date) — Query finish time.
• query_duration_ms (DateTime64) — Duration of query execution in milliseconds.
• exception_code (Enum) - Exception code from ZooKeeper.

Example

SELECT *
FROM system.distributed_ddl_queue
WHERE (cluster = 'test_cluster') AND (entry = 'query-0000000000')
LIMIT 2
FORMAT Vertical

Query id: 856f0efd-07c9-4f1a-815f-a19112df5bb3

Row 1:
──────
entry:             query-0000000000
host_name:         clickhouse01
host_address:      172.23.0.11
port:              9000
status:            finished
cluster:           test_cluster
value:            version: 1
query: CREATE DATABASE test_db UUID '40ac7692-70d3-48a9-bc29-4ade18957f59' ON CLUSTER test_cluster
hosts: ['clickhouse01:9000','clickhouse02:9000','clickhouse03:9000','clickhouse04:9000']
initiator: clickhouse01:9000

query_start_time:  2020-12-15 10:06:35
query_finish_time: 2020-12-15 10:06:35
query_duration_ms: 7
exception_code:    ZOK

Row 2:
──────
entry:             query-0000000000
host_name:         clickhouse02
host_address:      172.23.0.12
port:              9000
status:            finished
cluster:           test_cluster
value:            version: 1
query: CREATE DATABASE test_db UUID '40ac7692-70d3-48a9-bc29-4ade18957f59' ON CLUSTER test_cluster
hosts: ['clickhouse01:9000','clickhouse02:9000','clickhouse03:9000','clickhouse04:9000']
initiator: clickhouse01:9000

query_start_time:  2020-12-15 10:06:35
query_finish_time: 2020-12-15 10:06:35
query_duration_ms: 7
exception_code:    ZOK

2 rows in set. Elapsed: 0.032 sec. 

Original article