system.warnings

This table contains warning messages about clickhouse server.

Querying in ClickHouse Cloud

The data in this system table is held locally on each node in ClickHouse Cloud. Obtaining a complete view of all data, therefore, requires the clusterAllReplicas function. See here for further details.

Description

This table shows warnings about the ClickHouse server. Warnings of the same type are combined into a single warning. For example, if the number N of attached databases exceeds a configurable threshold T, a single entry containing the current value N is shown instead of N separate entries. If current value drops below the threshold, the entry is removed from the table.

The table can be configured with these settings:

• max_table_num_to_warn
• max_database_num_to_warn
• max_dictionary_num_to_warn
• max_view_num_to_warn
• max_part_num_to_warn
• max_pending_mutations_to_warn
• max_pending_mutations_execution_time_to_warn
• max_named_collection_num_to_warn
• resource_overload_warnings

Columns

• message (String) — Warning message.
• message_format_string (LowCardinality(String)) — The format string used to format the message.

Example

Query

 SELECT * FROM system.warnings LIMIT 2 \G;

Response

Row 1:
──────
message:               The number of active parts is more than 10.
message_format_string: The number of active parts is more than {}.

Row 2:
──────
message:               The number of attached databases is more than 2.
message_format_string: The number of attached databases is more than {}.