Logs in Managed Service for ClickHouse®

DoubleCloud maintains a log of events taking place in managed clusters that you can use for monitoring activity and debugging issues.

You can access logs in the Logs tab on the cluster page, or you can configure log export to external log management providers.

Log entries

Log entry records status or describes certain events in your cluster. These messages tell you that certain events occur in the cluster or show something is wrong and needs attention.

Log entry structure

A log entry contains the complete information on a logged event and consists of the following segments:

  • Date and time stamp in the YYYY/MM/DD, HH:MM:SS format.

  • Log level indicator.

  • Log entry text.

Log levels

Log level is a status that tells how important a log entry is.

DoubleCloud clusters support the following log levels:

Level

Description

TRACE

Detailed diagnostics information.

DEBUG

Debugging information.

INFO

Diagnostics information for statistics.

WARNING

Warning about a non-critical malfunction that you need to investigate further.

ERROR

Error report.

FATAL

Possible system failure, cluster shutdown.

Default values for system log tables

DoubleCloud Managed Service for ClickHouse® allows you to manage system.*_log tables:

  • Enable and disable the tables (except system.query_log and system.part_log).

  • Change the disk space allowed for the table (in bytes) - retention_size.

  • Change the table partition's retention time (in seconds) - retention_time.

    This parameter is used after conversion into days by the following formula:

    (ceil (table_retention_time / (60 * 60 * 24)))
    

    The resulting number determines the limit of partitions for the table. Each table has one partition per day.

Log tables cleanup schedule

Log tables are cleaned up once every 24 hours, after 0:00 according to the timezone of the cluster's region. This allows the peak usage to exceed the set limits.

system.query_log

You can't turn off this table

You can't apply system.query_log_enabled: false, only change the size and time.

Parameter

Default value

query_log_retention_size

1073741824

query_log_retention_time

2592000

system.query_thread_log

Parameter

Default value

query_thread_log_enabled

true

query_thread_log_retention_size

536870912

query_thread_log_retention_time

2592000

system.query_views_log

Parameter

Default value

query_views_log_enabled

false

query_views_log_retention_size

0

query_views_log_retention_time

2592000

system.part_log

You can't turn off this table

You can't apply system.part_log_enabled: false, only change the size and time.

Parameter

Default value

part_log_retention_size

536870912

part_log_retention_time

2592000

system.metric_log

Parameter

Default value

metric_log_enabled

true

metric_log_retention_size

536870912

metric_log_retention_time

2592000

system.asynchronous_metric_log:

Parameter

Default value

asynchronous_metric_log_enabled

false

asynchronous_metric_log_retention_size

0

asynchronous_metric_log_retention_time

2592000

system.text_log

Parameter

Default value

text_log_enabled

false

text_log_retention_size

536870912

text_log_retention_time

2592000

text_log_level

Trace

system.trace_log

Parameter

Default value

trace_log_enabled

false

trace_log_retention_size

536870912

trace_log_retention_time

2592000

system.opentelemetry_span_log

Parameter

Default value

opentelemetry_span_log_enabled

false

opentelemetry_span_log_retention_size

0

opentelemetry_span_log_retention_time

2592000

system.session_log

Parameter

Default value

session_log_enabled

false

session_log_retention_size

0

session_log_retention_time

2592000

system.zookeeper_log

Parameter

Default value

zookeeper_log_enabled

false

zookeeper_log_retention_size

0

zookeeper_log_retention_time

2592000

system.asynchronous_insert_log

Parameter

Default value

asynchronous_insert_log_enabled

false

asynchronous_insert_log_retention_size

0

asynchronous_insert_log_retention_time

2592000

See also