a6fb067a75
* Corrected en files * Split system-tables.md into separate files * Fixed links. * Fixed links. * Fixed links. * Fixed links. * Add ref to original article * Fixed links * Add toc_folder_title and translate * Add stack_trace.md, correct toc-title * Fixed links * Hypothesis testing * Hypothesis testing * Update run.sh, thanks @azat Co-authored-by: Anna Devyatova <annadevyatova@yandex-team.ru> Co-authored-by: Sergei Shtykov <bayonet@yandex-team.ru> Co-authored-by: alexey-milovidov <milovidov@yandex-team.ru>
2.5 KiB
system.trace_log
Contains stack traces collected by the sampling query profiler.
ClickHouse creates this table when the trace_log server configuration section is set. Also the query_profiler_real_time_period_ns and query_profiler_cpu_time_period_ns settings should be set.
To analyze logs, use the addressToLine, addressToSymbol and demangle introspection functions.
Columns:
-
event_date(Date) — Date of sampling moment. -
event_time(DateTime) — Timestamp of sampling moment. -
revision(UInt32) — ClickHouse server build revision.When connecting to server by `clickhouse-client`, you see the string similar to `Connected to ClickHouse server version 19.18.1 revision 54429.`. This field contains the `revision`, but not the `version` of a server. -
timer_type(Enum8) — Timer type:- `Real` represents wall-clock time. - `CPU` represents CPU time. -
thread_number(UInt32) — Thread identifier. -
query_id(String) — Query identifier that can be used to get details about a query that was running from the query_log system table. -
trace(Array(UInt64)) — Stack trace at the moment of sampling. Each element is a virtual memory address inside ClickHouse server process.
Example
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]