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

slug
/en/operations/system-tables/distributed_ddl_queue

distributed_ddl_queue

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

Columns:

• entry (String) — Query id.
• entry_version (Nullable(UInt8)) - Version of the entry
• initiator_host (Nullable(String)) - Host that initiated the DDL operation
• initiator_port (Nullable(UInt16)) - Port used by the initiator
• cluster (String) — Cluster name.
• query (String) — Query executed.
• settings (Map(String, String)) - Settings used in the DDL operation
• query_create_time (DateTime) — Query created time.
• host (String) — Hostname
• port (UInt16) — Host Port.
• status (Enum8) — Status of the query.
• exception_code (Enum8) — Exception code.
• exception_text (Nullable(String)) - Exception message
• query_finish_time (DateTime) — Query finish time.
• query_duration_ms (UInt64) — Duration of query execution (in milliseconds).

Example

SELECT *
FROM system.distributed_ddl_queue
WHERE cluster = 'test_cluster'
LIMIT 2
FORMAT Vertical

Query id: f544e72a-6641-43f1-836b-24baa1c9632a

Row 1:
──────
entry:             query-0000000000
entry_version:     5
initiator_host:    clickhouse01
initiator_port:    9000
cluster:           test_cluster
query:             CREATE DATABASE test_db UUID '4a82697e-c85e-4e5b-a01e-a36f2a758456' ON CLUSTER test_cluster
settings:          {'max_threads':'16','use_uncompressed_cache':'0'}
query_create_time: 2023-09-01 16:15:14
host:              clickhouse-01
port:              9000
status:            Finished
exception_code:    0
exception_text:    
query_finish_time: 2023-09-01 16:15:14
query_duration_ms: 154

Row 2:
──────
entry:             query-0000000001
entry_version:     5
initiator_host:    clickhouse01
initiator_port:    9000
cluster:           test_cluster
query:             CREATE DATABASE test_db UUID '4a82697e-c85e-4e5b-a01e-a36f2a758456' ON CLUSTER test_cluster
settings:          {'max_threads':'16','use_uncompressed_cache':'0'}
query_create_time: 2023-09-01 16:15:14
host:              clickhouse-01
port:              9000
status:            Finished
exception_code:    630
exception_text:    Code: 630. DB::Exception: Cannot drop or rename test_db, because some tables depend on it:
query_finish_time: 2023-09-01 16:15:14
query_duration_ms: 154

2 rows in set. Elapsed: 0.025 sec.