Fetch query statistics for Managed ClickHouse®

Query statistics in ClickHouse are available in the system.query_log table, which stores statistics of each executed query, including memory usage, duration, rows and bytes read.

In Managed ClickHouse®, system.query_log is accessible with standard SQL:

SELECT
    query_duration_ms,
    read_rows,
    formatReadableSize(read_bytes) AS data_read
FROM system.query_log
WHERE type = 'QueryFinish'
ORDER BY event_time DESC
LIMIT 10;

type = 'QueryFinish' matches only queries that completed successfully. Failed queries are logged with type set to ExceptionBeforeStart or ExceptionWhileProcessing, so errors need their own query:

SELECT
    event_time,
    type,
    exception_code,
    exception,
    query
FROM system.query_log
WHERE type IN ('ExceptionBeforeStart', 'ExceptionWhileProcessing')
ORDER BY event_time DESC
LIMIT 10;

To inspect one specific statement, for example an ingest you have just run, filter on the query text and read the memory peak alongside the duration:

SELECT
    query_duration_ms,
    read_rows,
    formatReadableSize(read_bytes) AS data_read,
    formatReadableSize(memory_usage) AS memory_peak
FROM system.query_log
WHERE type = 'QueryFinish' AND query LIKE 'INSERT INTO trips%'
ORDER BY event_time DESC
LIMIT 1;

Note

System log tables in Managed ClickHouse keep data for 1 day. To retain query statistics for longer, persist them with a materialized view. See ClickHouse system tables for the retention details and the materialized view pattern.

Last updated on August 18, 2026

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