ClickHouse问题排查心得

DevOps
留言

腾讯云后台只能看整体情况

其他指标也是断崖式下降

查看查询日志中的历史查询:

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SELECT 
    query_id,
    user,
    query,
    query_duration_ms,
    read_rows,
    read_bytes,
    memory_usage,
    ProfileEvents.Names,
    ProfileEvents.Values
FROM system.query_log
WHERE event_time >= now() - INTERVAL 1 HOUR
  AND type = 'QueryFinish'
ORDER BY query_duration_ms DESC
LIMIT 10;

查看CPU使用情况相关的指标:

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SELECT 
    query_id,
    user,
    query,
    query_duration_ms,
    ProfileEvents['UserTimeMicroseconds'] as user_cpu_time,
    ProfileEvents['SystemTimeMicroseconds'] as system_cpu_time,
    ProfileEvents['OSCPUVirtualTimeMicroseconds'] as virtual_cpu_time
FROM system.query_log
WHERE event_time >= now() - INTERVAL 1 HOUR
  AND type = 'QueryFinish'
  AND ProfileEvents['UserTimeMicroseconds'] > 0
ORDER BY ProfileEvents['UserTimeMicroseconds'] DESC
LIMIT 10;

查看当前正在执行的查询 (意义不太大)

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SELECT 
    query_id,
    user,
    query,
    elapsed,
    read_rows,
    read_bytes,
    memory_usage,
    thread_ids
FROM system.processes
ORDER BY elapsed DESC;

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