mysqld_qslower(8)

✨ mysqld_qslower(8) ✨

System Manager's Manual 🎀

💖 NAME 💖

mysqld_qslower — traces MySQL server queries that are slower than a threshold 🦋

🧚 SYNOPSIS 🧚

mysqld_qslower PID [min_ms]

📖 DESCRIPTION 📖

okay so this traces the queries a MySQL server is serving and only prints the ones that go over a latency (aka query duration) threshold you pick 👀✨ by default the minimum is 1 millisecond. if you set the threshold to 0, literally every query gets printed 💀

this one uses User Statically-Defined Tracing (USDT) probes, which MySQL added for DTrace support. ngl that feature might not be switched on for your MySQL install, so check the requirements section 🙈

also, since this tool runs on BPF, only the root user can use it 🔥 no cap, bring your root energy or it's a no 😭

🎀 REQUIREMENTS 🎀

you'll need CONFIG_BPF, bcc, and a MySQL server built with USDT probe support. that last one is set when you configure the build with -DENABLE_DTRACE=1 💅

⭐ OPTIONS ⭐

• PID — the mysqld process ID you want to trace 🌸
• min_ms — the minimum query latency (duration) to trace, in milliseconds. it defaults to 1 ms if you don't pass it 🍓

🌈 EXAMPLES 🌈

trace MySQL server queries slower than 1 ms for PID 1981 🦋

# mysqld_qslower 1981

trace anything slower than 10 ms for PID 1981 ✨

# mysqld_qslower 1981 10

💜 FIELDS 💜

the output has four columns, bestie:

• TIME(s) — when the query started, in seconds ⏰
• PID — the process ID of the traced server 🫶
• MS — how many milliseconds the query took, from start to end 🔥
• QUERY — the query string, cut off at 128 characters ✂️

🦋 OVERHEAD 🦋

this adds low-overhead instrumentation to MySQL queries, and it only pushes data from the kernel up to user level when a query goes over the threshold, which is so smart 🧠 if the server handles less than 1,000/sec, the overhead should be negligible 💖 if your query rate is higher, go test it and see what the overhead looks like for you 🙈

🍓 SOURCE 🍓

this comes from bcc 🫶

https://github.com/iovisor/bcc

also look in the bcc distribution for a companion _examples.txt file. it has example usage, output, and commentary for this tool, and it's giving very helpful notes ✨

🌸 OS 🌸

Linux 🐧

🧪 STABILITY 🧪

Unstable - in development. so it's still cooking 🍳

👑 AUTHOR 👑

Brendan Gregg 💅

🔗 SEE ALSO 🔗

biosnoop(8) 🦋

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bestie, that's the whole page! 💜 this is the USER COMMANDS manual, dated 2016-08-01, for mysqld_qslower(8) 🎀 stay curious and keep those queries fast 🌈✨