تاریخ با ساعت 4 بایت به صورت Unix timestamp ذخیره می کند (unsigned). به شما اجازه ی ذخیره سازی در محدوده ی تایپ Date را می دهد. حداقل مقدار در خروجی 0000-00-00 00:00:00 می باشد. زمان با دقت تا یک ثانیه ذخیره می شود.
@@ -474,6 +474,91 @@ ClickHouse создаёт таблицу только в том случае, к
Можно указать произвольный ключ партиционирования для таблицы `system.query_log` в конфигурации [query_log](server_settings/settings.md#server_settings-query-log)(параметр`partition_by`).
## system.query_log {#system_tables-query_log}
Contains information about execution of queries. For each query, you can see processing start time, duration of processing, error messages and other information.
!!! note "Note"
The table doesn't contain input data for `INSERT` queries.
ClickHouse creates this table only if the [query_log](server_settings/settings.md#server_settings-query-log) server parameter is specified. This parameter sets the logging rules, such as the logging interval or the name of the table the queries will be logged in.
To enable query logging, set the [log_queries](settings/settings.md#settings-log-queries) parameter to 1. For details, see the [Settings](settings/settings.md) section.
The `system.query_log` table registers two kinds of queries:
1. Initial queries that were run directly by the client.
2. Child queries that were initiated by other queries (for distributed query execution). For these types of queries, information about the parent queries is shown in the `initial_*` columns.
Columns:
-`type` (`Enum8`) — Type of event that occurred when executing the query. Values:
-`'QueryStart' = 1` — Successful start of query execution.
-`'QueryFinish' = 2` — Successful end of query execution.
-`'ExceptionBeforeStart' = 3` — Exception before the start of query execution.
-`'ExceptionWhileProcessing' = 4` — Exception during the query execution.
-`event_date` (Date) — Query starting date.
-`event_time` (DateTime) — Query starting time.
-`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 `INSERT` queries, the number of written rows. For other queries, the column value is 0.
-`written_bytes` (UInt64) — For `INSERT` queries, the number of written bytes. For other queries, the column value is 0.
-`result_rows` (UInt64) — Number of rows in the result.
-`result_bytes` (UInt64) — Number of bytes in the result.
-`memory_usage` (UInt64) — Memory consumption by the query.
-`query` (String) — Query string.
-`exception` (String) — Exception message.
-`stack_trace` (String) — Stack trace (a list of methods called before the error occurred). An empty string, if the query is completed successfully.
-`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](../interfaces/cli.md).
-`client_hostname` (String) — Hostname of the client machine where the [clickhouse-client](../interfaces/cli.md) or another TCP client is run.
-`client_name` (String) — The [clickhouse-client](../interfaces/cli.md) or another TCP client name.
-`client_revision` (UInt32) — Revision of the [clickhouse-client](../interfaces/cli.md) or another TCP client.
-`client_version_major` (UInt32) — Major version of the [clickhouse-client](../interfaces/cli.md) or another TCP client.
-`client_version_minor` (UInt32) — Minor version of the [clickhouse-client](../interfaces/cli.md) or another TCP client.
-`client_version_patch` (UInt32) — Patch component of the [clickhouse-client](../interfaces/cli.md) 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 — `GET` method was used.
- 2 — `POST` method was used.
-`http_user_agent` (String) — The `UserAgent` header passed in the HTTP request.
-`quota_key` (String) — The "quota key" specified in the [quotas](quotas.md) setting (see `keyed`).
-`revision` (UInt32) — ClickHouse revision.
-`thread_numbers` (Array(UInt32)) — Number of threads that are participating in query execution.
-`ProfileEvents.Names` (Array(String)) — Counters that measure different metrics. The description of them could be found in the table [system.events](#system_tables-events)
-`ProfileEvents.Values` (Array(UInt64)) — Values of metrics that are listed in the `ProfileEvents.Names` column.
-`Settings.Names` (Array(String)) — Names of settings that were changed when the client ran the query. To enable logging changes to settings, set the `log_query_settings` parameter to 1.
-`Settings.Values` (Array(String)) — Values of settings that are listed in the `Settings.Names` column.
Each query creates one or two rows in the `query_log` table, depending on the status of the query:
1. If the query execution is successful, two events with types 1 and 2 are created (see the `type` column).
2. If an error occurred during query processing, two events with types 1 and 4 are created.
3. If an error occurred before launching the query, a single event with type 3 is created.
By default, logs are added to the table at intervals of 7.5 seconds. You can set this interval in the [query_log](server_settings/settings.md#server_settings-query-log) server setting (see the `flush_interval_milliseconds` parameter). To flush the logs forcibly from the memory buffer into the table, use the `SYSTEM FLUSH LOGS` query.
When the table is deleted manually, it will be automatically created on the fly. Note that all the previous logs will be deleted.
!!! note
The storage period for logs is unlimited. Logs aren't automatically deleted from the table. You need to organize the removal of outdated logs yourself.
You can specify an arbitrary partitioning key for the `system.query_log` table in the [query_log](server_settings/settings.md#server_settings-query-log) server setting (see the `partition_by` parameter).
@@ -104,7 +104,7 @@ Defines storage time for values. Can be specified only for MergeTree-family tabl
### Column Compression Codecs {#codecs}
By default, ClickHouse applies the compression method, defined in [server settings](../operations/server_settings/settings.md#compression), to columns. You can also define the compression method for each individual column in the `CREATE TABLE` query.
By default, ClickHouse applies the compression method, defined in [server settings](../operations/server_settings/settings.md#server-settings-compression), to columns. You can also define the compression method for each individual column in the `CREATE TABLE` query.
