import SystemTableCloud from '@site/docs/_snippets/_system_table_cloud.md';

system.warnings

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;

Result:

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 {}.