Contains information about threads which execute queries, for example, thread name, thread start time, duration of query processing.
To start logging:
ClickHouse doesn’t delete data from the table automatically. See Introduction for more details.
event_date(Date) — The date when the thread has finished execution of the query.
event_time(DateTime) — The date and time when the thread has finished execution of the query.
query_start_time(DateTime) — Start time of query execution.
query_duration_ms(UInt64) — Duration of query execution.
read_rows(UInt64) — Number of read rows.
read_bytes(UInt64) — Number of read bytes.
written_rows(UInt64) — For
INSERTqueries, the number of written rows. For other queries, the column value is 0.
written_bytes(UInt64) — For
INSERTqueries, the number of written bytes. For other queries, the column value is 0.
memory_usage(Int64) — The difference between the amount of allocated and freed memory in context of this thread.
peak_memory_usage(Int64) — The maximum difference between the amount of allocated and freed memory in context of this thread.
thread_name(String) — Name of the thread.
thread_number(UInt32) — Internal thread ID.
thread_id(Int32) — thread ID.
master_thread_id(UInt64) — OS initial ID of initial thread.
query(String) — Query string.
is_initial_query(UInt8) — Query type. Possible values:
- 1 — Query was initiated by the client.
- 0 — Query was initiated by another query for distributed query execution.
user(String) — Name of the user who initiated the current query.
query_id(String) — ID of the query.
address(IPv6) — IP address that was used to make the query.
port(UInt16) — The client port that was used to make the query.
initial_user(String) — Name of the user who ran the initial query (for distributed query execution).
initial_query_id(String) — ID of the initial query (for distributed query execution).
initial_address(IPv6) — IP address that the parent query was launched from.
initial_port(UInt16) — The client port that was used to make the parent query.
interface(UInt8) — Interface that the query was initiated from. Possible values:
- 1 — TCP.
- 2 — HTTP.
os_user(String) — OS’s username who runs clickhouse-client.
client_hostname(String) — Hostname of the client machine where the clickhouse-client or another TCP client is run.
client_name(String) — The clickhouse-client or another TCP client name.
client_revision(UInt32) — Revision of the clickhouse-client or another TCP client.
client_version_major(UInt32) — Major version of the clickhouse-client or another TCP client.
client_version_minor(UInt32) — Minor version of the clickhouse-client or another TCP client.
client_version_patch(UInt32) — Patch component of the clickhouse-client or another TCP client version.
http_method(UInt8) — HTTP method that initiated the query. Possible values:
- 0 — The query was launched from the TCP interface.
- 1 —
GETmethod was used.
- 2 —
POSTmethod was used.
http_user_agent(String) — The
UserAgentheader passed in the HTTP request.
quota_key(String) — The “quota key” specified in the quotas setting (see
revision(UInt32) — ClickHouse revision.
ProfileEvents.Names(Array(String)) — Counters that measure different metrics for this thread. The description of them could be found in the table system.events.
ProfileEvents.Values(Array(UInt64)) — Values of metrics for this thread that are listed in the
SELECT * FROM system.query_thread_log LIMIT 1 FORMAT Vertical
Row 1: ────── event_date: 2020-05-13 event_time: 2020-05-13 14:02:28 query_start_time: 2020-05-13 14:02:28 query_duration_ms: 0 read_rows: 1 read_bytes: 1 written_rows: 0 written_bytes: 0 memory_usage: 0 peak_memory_usage: 0 thread_name: QueryPipelineEx thread_id: 28952 master_thread_id: 28924 query: SELECT 1 is_initial_query: 1 user: default query_id: 5e834082-6f6d-4e34-b47b-cd1934f4002a address: ::ffff:127.0.0.1 port: 57720 initial_user: default initial_query_id: 5e834082-6f6d-4e34-b47b-cd1934f4002a initial_address: ::ffff:127.0.0.1 initial_port: 57720 interface: 1 os_user: bayonet client_hostname: clickhouse.ru-central1.internal client_name: ClickHouse client client_revision: 54434 client_version_major: 20 client_version_minor: 4 client_version_patch: 1 http_method: 0 http_user_agent: quota_key: revision: 54434 ProfileEvents.Names: ['ContextLock','RealTimeMicroseconds','UserTimeMicroseconds','OSCPUWaitMicroseconds','OSCPUVirtualTimeMicroseconds'] ProfileEvents.Values: [1,97,81,5,81] ...
- system.query_log — Description of the
query_logsystem table which contains common information about queries execution.