系统。trace_log

包含采样查询探查器收集的堆栈跟踪。

ClickHouse创建此表时 trace_log 服务器配置部分被设置。 也是 query_profiler_real_time_period_ns 和 query_profiler_cpu_time_period_ns 应设置设置。

要分析日志，请使用 addressToLine, addressToSymbol 和 demangle 内省功能。

列:

• event_date (日期) — Date of sampling moment.

• event_time (日期时间) — Timestamp of the sampling moment.

• timestamp_ns (UInt64) — Timestamp of the sampling moment in nanoseconds.

• revision (UInt32) — ClickHouse server build revision.

  通过以下方式连接到服务器 clickhouse-client，你看到的字符串类似于 Connected to ClickHouse server version 19.18.1.. 该字段包含 revision，但不是 version 的服务器。

• timer_type (枚举8) — Timer type:

  • Real 表示挂钟时间。
  • CPU 表示CPU时间。

• thread_number (UInt32) — Thread identifier.

• query_id (字符串) — Query identifier that can be used to get details about a query that was running from the query_log 系统表.

• trace (数组(UInt64)) — Stack trace at the moment of sampling. Each element is a virtual memory address inside ClickHouse server process.

示例

SELECT * FROM system.trace_log LIMIT 1 \G

Row 1:
──────
event_date:    2019-11-15
event_time:    2019-11-15 15:09:38
revision:      54428
timer_type:    Real
thread_number: 48
query_id:      acc4d61f-5bd1-4a3e-bc91-2180be37c915
trace:         [94222141367858,94222152240175,94222152325351,94222152329944,94222152330796,94222151449980,94222144088167,94222151682763,94222144088167,94222151682763,94222144088167,94222144058283,94222144059248,94222091840750,94222091842302,94222091831228,94222189631488,140509950166747,140509942945935]