In order to execute the same query on all nodes of a ClickHouse Cloud service, we can use clusterAllReplicas.

ClickHouse provides a simple and intuitive way to write filtered aggregates.

ClickHouse uses threads from the Global Thread pool to process queries and also perform background operations like merges and mutations. If there is no idle thread to process a query, then a new thread is created in the pool.

When a user-level setting is specified in the wrong place, the server won't start and an exception message is sent to the log. However, you can tell ClickHouse to ignore the incorrect setting using the skip_check_for_incorrect_settings setting.

A client can view the server logs - even at a different level than what the server log level is configured to - by setting the send_logs_level client setting.

To compare metrics between two queries, you must first obtain the query_id for both queries.

Overview of billing information.

Details on using CSP marketplaces to subscribe to ClickHouse Cloud.

The root cause of these permissions errors has been identified and is due to more strict checking of grants in the new release for async_inserts.

Problem

Map lookup such as a['key'] works with linear complexity (mentioned here) and can be inefficient. This is because selecting a value with a specific key from a table would require iterating through all keys (~M) across all rows (N) in the Map column, resulting in ~MxN lookups.