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9.2 KiB
Markdown
123 lines
9.2 KiB
Markdown
---
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slug: /en/operations/system-tables/query_thread_log
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---
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# query_thread_log
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Contains information about threads that execute queries, for example, thread name, thread start time, duration of query processing.
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To start logging:
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1. Configure parameters in the [query_thread_log](../../operations/server-configuration-parameters/settings.md#server_configuration_parameters-query_thread_log) section.
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2. Set [log_query_threads](../../operations/settings/settings.md#log-query-threads) to 1.
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The flushing period of data is set in `flush_interval_milliseconds` parameter of the [query_thread_log](../../operations/server-configuration-parameters/settings.md#server_configuration_parameters-query_thread_log) server settings section. To force flushing, use the [SYSTEM FLUSH LOGS](../../sql-reference/statements/system.md#query_language-system-flush_logs) query.
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ClickHouse does not delete data from the table automatically. See [Introduction](../../operations/system-tables/index.md#system-tables-introduction) for more details.
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You can use the [log_queries_probability](../../operations/settings/settings.md#log-queries-probability) setting to reduce the number of queries, registered in the `query_thread_log` table.
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Columns:
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- `hostname` ([LowCardinality(String)](../../sql-reference/data-types/string.md)) — Hostname of the server executing the query.
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- `event_date` ([Date](../../sql-reference/data-types/date.md)) — The date when the thread has finished execution of the query.
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- `event_time` ([DateTime](../../sql-reference/data-types/datetime.md)) — The date and time when the thread has finished execution of the query.
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- `event_time_microsecinds` ([DateTime](../../sql-reference/data-types/datetime.md)) — The date and time when the thread has finished execution of the query with microseconds precision.
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- `query_start_time` ([DateTime](../../sql-reference/data-types/datetime.md)) — Start time of query execution.
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- `query_start_time_microseconds` ([DateTime64](../../sql-reference/data-types/datetime64.md)) — Start time of query execution with microsecond precision.
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- `query_duration_ms` ([UInt64](../../sql-reference/data-types/int-uint.md#uint-ranges)) — Duration of query execution.
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- `read_rows` ([UInt64](../../sql-reference/data-types/int-uint.md#uint-ranges)) — Number of read rows.
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- `read_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md#uint-ranges)) — Number of read bytes.
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- `written_rows` ([UInt64](../../sql-reference/data-types/int-uint.md#uint-ranges)) — For `INSERT` queries, the number of written rows. For other queries, the column value is 0.
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- `written_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md#uint-ranges)) — For `INSERT` queries, the number of written bytes. For other queries, the column value is 0.
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- `memory_usage` ([Int64](../../sql-reference/data-types/int-uint.md)) — The difference between the amount of allocated and freed memory in context of this thread.
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- `peak_memory_usage` ([Int64](../../sql-reference/data-types/int-uint.md)) — The maximum difference between the amount of allocated and freed memory in context of this thread.
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- `thread_name` ([String](../../sql-reference/data-types/string.md)) — Name of the thread.
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- `thread_number` ([UInt32](../../sql-reference/data-types/int-uint.md)) — Internal thread ID.
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- `thread_id` ([Int32](../../sql-reference/data-types/int-uint.md)) — thread ID.
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- `master_thread_id` ([UInt64](../../sql-reference/data-types/int-uint.md#uint-ranges)) — OS initial ID of initial thread.
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- `query` ([String](../../sql-reference/data-types/string.md)) — Query string.
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- `is_initial_query` ([UInt8](../../sql-reference/data-types/int-uint.md#uint-ranges)) — Query type. Possible values:
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- 1 — Query was initiated by the client.
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- 0 — Query was initiated by another query for distributed query execution.
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- `user` ([String](../../sql-reference/data-types/string.md)) — Name of the user who initiated the current query.
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- `query_id` ([String](../../sql-reference/data-types/string.md)) — ID of the query.
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- `address` ([IPv6](../../sql-reference/data-types/ipv6.md)) — IP address that was used to make the query.
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- `port` ([UInt16](../../sql-reference/data-types/int-uint.md#uint-ranges)) — The client port that was used to make the query.
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- `initial_user` ([String](../../sql-reference/data-types/string.md)) — Name of the user who ran the initial query (for distributed query execution).
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- `initial_query_id` ([String](../../sql-reference/data-types/string.md)) — ID of the initial query (for distributed query execution).
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- `initial_address` ([IPv6](../../sql-reference/data-types/ipv6.md)) — IP address that the parent query was launched from.
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- `initial_port` ([UInt16](../../sql-reference/data-types/int-uint.md#uint-ranges)) — The client port that was used to make the parent query.
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- `interface` ([UInt8](../../sql-reference/data-types/int-uint.md#uint-ranges)) — Interface that the query was initiated from. Possible values:
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- 1 — TCP.
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- 2 — HTTP.
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- `os_user` ([String](../../sql-reference/data-types/string.md)) — OS’s username who runs [clickhouse-client](../../interfaces/cli.md).
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- `client_hostname` ([String](../../sql-reference/data-types/string.md)) — Hostname of the client machine where the [clickhouse-client](../../interfaces/cli.md) or another TCP client is run.
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- `client_name` ([String](../../sql-reference/data-types/string.md)) — The [clickhouse-client](../../interfaces/cli.md) or another TCP client name.
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- `client_revision` ([UInt32](../../sql-reference/data-types/int-uint.md)) — Revision of the [clickhouse-client](../../interfaces/cli.md) or another TCP client.
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- `client_version_major` ([UInt32](../../sql-reference/data-types/int-uint.md)) — Major version of the [clickhouse-client](../../interfaces/cli.md) or another TCP client.
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- `client_version_minor` ([UInt32](../../sql-reference/data-types/int-uint.md)) — Minor version of the [clickhouse-client](../../interfaces/cli.md) or another TCP client.
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- `client_version_patch` ([UInt32](../../sql-reference/data-types/int-uint.md)) — Patch component of the [clickhouse-client](../../interfaces/cli.md) or another TCP client version.
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- `http_method` ([UInt8](../../sql-reference/data-types/int-uint.md#uint-ranges)) — HTTP method that initiated the query. Possible values:
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- 0 — The query was launched from the TCP interface.
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- 1 — `GET` method was used.
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- 2 — `POST` method was used.
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- `http_user_agent` ([String](../../sql-reference/data-types/string.md)) — The `UserAgent` header passed in the HTTP request.
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- `quota_key` ([String](../../sql-reference/data-types/string.md)) — The “quota key” specified in the [quotas](../../operations/quotas.md) setting (see `keyed`).
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- `revision` ([UInt32](../../sql-reference/data-types/int-uint.md)) — ClickHouse revision.
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- `ProfileEvents` ([Map(String, UInt64)](../../sql-reference/data-types/array.md)) — ProfileEvents that measure different metrics for this thread. The description of them could be found in the table [system.events](#system_tables-events).
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**Example**
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``` sql
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SELECT * FROM system.query_thread_log LIMIT 1 \G
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```
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``` text
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Row 1:
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──────
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hostname: clickhouse.eu-central1.internal
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event_date: 2020-09-11
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event_time: 2020-09-11 10:08:17
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event_time_microseconds: 2020-09-11 10:08:17.134042
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query_start_time: 2020-09-11 10:08:17
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query_start_time_microseconds: 2020-09-11 10:08:17.063150
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query_duration_ms: 70
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read_rows: 0
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read_bytes: 0
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written_rows: 1
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written_bytes: 12
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memory_usage: 4300844
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peak_memory_usage: 4300844
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thread_name: TCPHandler
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thread_id: 638133
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master_thread_id: 638133
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query: INSERT INTO test1 VALUES
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is_initial_query: 1
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user: default
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query_id: 50a320fd-85a8-49b8-8761-98a86bcbacef
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address: ::ffff:127.0.0.1
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port: 33452
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initial_user: default
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initial_query_id: 50a320fd-85a8-49b8-8761-98a86bcbacef
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initial_address: ::ffff:127.0.0.1
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initial_port: 33452
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interface: 1
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os_user: bharatnc
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client_hostname: tower
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client_name: ClickHouse
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client_revision: 54437
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client_version_major: 20
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client_version_minor: 7
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client_version_patch: 2
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http_method: 0
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http_user_agent:
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quota_key:
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revision: 54440
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ProfileEvents: {'Query':1,'SelectQuery':1,'ReadCompressedBytes':36,'CompressedReadBufferBlocks':1,'CompressedReadBufferBytes':10,'IOBufferAllocs':1,'IOBufferAllocBytes':89,'ContextLock':15,'RWLockAcquiredReadLocks':1}
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```
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**See Also**
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- [system.query_log](../../operations/system-tables/query_log.md#system_tables-query_log) — Description of the `query_log` system table which contains common information about queries execution.
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- [system.query_views_log](../../operations/system-tables/query_views_log.md#system_tables-query_views_log) — This table contains information about each view executed during a query.
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