ClickHouse Log Overview

Log Description

Log path: The default storage path of ClickHouse log files is as follows: ${BIGDATA_LOG_HOME}/clickhouse

Log archive rule: The automatic ClickHouse log compression function is enabled. By default, when the size of logs exceeds 100 MB, logs are automatically compressed into a log file named in the following format: <Original log name>.[ID].gz. A maximum of 10 latest compressed files are reserved by default. The number of compressed files can be configured on Manager.

**Table 1** ClickHouse log list
Log Type	Log File Name	Description
Run logs	/var/log/Bigdata/clickhouse/clickhouseServer/clickhouse-server.err.log	Path of ClickHouseServer error log files.
	/var/log/Bigdata/clickhouse/clickhouseServer/checkService.log	Path of key ClickHouseServer run log files.
	/var/log/Bigdata/clickhouse/clickhouseServer/clickhouse-server.log	Path of key ClickHouseServer run log files.
	/var/log/Bigdata/clickhouse/balance/start.log	Path of ClickHouseBalancer startup log files.
	/var/log/Bigdata/clickhouse/balance/error.log	Path of ClickHouseBalancer error log files.
	/var/log/Bigdata/clickhouse/balance/access_http.log	Path of ClickHouseBalancer run log files.
Data migration logs	/var/log/Bigdata/clickhouse/migration/Data migration task name/clickhouse-copier_{timestamp}_{processId}/copier.log	Run logs generated when you use the migration tool by referring to Using the ClickHouse Data Migration Tool.
Data migration logs	/var/log/Bigdata/clickhouse/migration/Data migration task name/clickhouse-copier_{timestamp}_{processId}/copier.err.log	Error logs generated when you use the migration tool by referring to Using the ClickHouse Data Migration Tool.

Log Level

Table 2 describes the log levels supported by ClickHouse.

Levels of run logs are error, warning, trace, information, and debug from the highest to the lowest priority. Run logs of equal or higher levels are recorded. The higher the specified log level, the fewer the logs recorded.

**Table 2** Log levels
Log Type	Level	Description
Run log	error	Logs of this level record error information about system running.
	warning	Logs of this level record exception information about the current event processing.
	trace	Logs of this level record trace information about the current event processing.
	information	Logs of this level record normal running status information about the system and events.
	debug	Logs of this level record system running and debugging information.

To modify log levels, perform the following operations:

Log in to FusionInsight Manager.
Choose Cluster > Services > ClickHouse > Configurations.
Select All Configurations.
On the menu bar on the left, select the log menu of the target role.
Select a desired log level.
Click Save. Then, click OK.

The configurations take effect immediately without the need to restart the service.

Log Format

The following table lists the ClickHouse log format:

**Table 3** Log formats
Log Type	Format	Example
Run log	<yyyy-MM-dd HH:mm:ss,SSS>\|<Log level>\|<Name of the thread that generates the log>\|<Message in the log>\|<Location where the log event occurs>	2021.02.23 15:26:30.691301 [ 6085 ] {} <Error> DynamicQueryHandler: Code: 516, e.displayText() = DB::Exception: default: Authentication failed: password is incorrect or there is no user with such name, Stack trace (when copying this message, always include the lines below): 0. Poco::Exception::Exception(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, int) @ 0x1250e59c