mysqld\_qslower(8) System Manager's Manual mysqld\_qslower(8)

# [NAME](#NAME)

mysqld\_qslower - Trace MySQL server queries slower than a threshold.

# [SYNOPSIS](#SYNOPSIS)

**mysqld\_qslower PID \[min\_ms]**

# [DESCRIPTION](#DESCRIPTION)

This traces queries served by a MySQL server, and prints those that exceed a custom latency (query duration) threshold. By default, a minimum threshold of 1 millisecond is used. If a threshold of 0 is used, all queries are printed.

This uses User Statically-Defined Tracing (USDT) probes, a feature added to MySQL for DTrace support, but which may not be enabled on a given MySQL installation. See requirements.

Since this uses BPF, only the root user can use this tool.

# [REQUIREMENTS](#REQUIREMENTS)

CONFIG\_BPF, bcc, and MySQL server with USDT probe support (when configuring the build: -DENABLE\_DTRACE=1).

# [OPTIONS](#OPTIONS)

PID Trace this mysqld PID.

[min\_ms](#min_ms)

Minimum query latency (duration) to trace, in milliseconds. Default is 1 ms.

# [EXAMPLES](#EXAMPLES)

[Trace MySQL server queries slower than 1 ms for PID 1981:](#Trace)

\# **mysqld\_qslower 1981**

[Trace slower than 10 ms for PID 1981:](#Trace~2)

\# **mysqld\_qslower 1981 10**

# [FIELDS](#FIELDS)

[TIME(s)](#TIME%28s%29)

Time of query start, in seconds.

[PID](#PID)

Process ID of the traced server.

[MS](#MS)

Milliseconds for the query, from start to end.

[QUERY](#QUERY)

Query string, truncated to 128 characters.

# [OVERHEAD](#OVERHEAD)

This adds low-overhead instrumentation to MySQL queries, and only emits output data from kernel to user-level if they query exceeds the threshold. If the server query rate is less than 1,000/sec, the overhead is expected to be negligible. If the query rate is higher, test to gauge overhead.

# [SOURCE](#SOURCE)

This is from bcc.

https://github.com/iovisor/bcc

Also look in the bcc distribution for a companion \_examples.txt file containing example usage, output, and commentary for this tool.

# [OS](#OS)

Linux

# [STABILITY](#STABILITY)

Unstable - in development.

# [AUTHOR](#AUTHOR)

Brendan Gregg

# [SEE ALSO](#SEE_ALSO)

[biosnoop(8)](/man/enterprise-packages/bcc/biosnoop.8)

2016-08-01 USER COMMANDS

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Document: mysqld_qslower(8) from bcc 0.37.0-r3 (Chainguard OS)
Source: https://github.com/iovisor/bcc