dbslower(8)

💖 dbslower(8) 💖

System Manager's Manual ✨ okay bestie, this is the manual page for dbslower, so let's get into it 🫶

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✨ NAME ✨

okay so dbslower is the tool that traces MySQL and PostgreSQL server queries that are slower than a threshold 🐢 It's giving detective 🕵️‍♀️

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🎀 SYNOPSIS 🎀

dbslower [-v] [-p PID [PID ...]] [-x PATH] [-m THRESHOLD]
{mysql,postgres}

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💅 DESCRIPTION 💅

okay so this traces queries served by a MySQL or PostgreSQL server and prints the ones that go over a latency (query time) threshold ⏱️ by default the threshold is 1 ms, so anything slower than that shows up 👀

this uses User Statically-Defined Tracing (USDT) probes, which MySQL and PostgreSQL added for DTrace support 🦋 BUT these probes might not be turned on for your installation, so check the REQUIREMENTS section first 🙈 if you're on MySQL, you can still trace queries without USDT using the -x option ✨

⚠️ since this uses BPF, only the root user can use this tool. no root, no dbslower, sorry bestie 💀

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📋 REQUIREMENTS 📋

you'll need CONFIG_BPF, bcc, and either:

• a MySQL server with USDT probe support (set when configuring the build with -DENABLE_DTRACE=1) 🐬
• or a PostgreSQL server with USDT probe support (set when configuring the build with --enable-dtrace) 🐘

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🌸 OPTIONS 🌸

• -h — okay this one just prints the usage message 💌
• -p PID — traces this PID 🎯 if you don't give a PID, the tool tries to auto-detect the MySQL or PostgreSQL processes running on the system, so it does the work for you 🧚
• -x PATH — the path to the MySQL binary 🪄 this lets you trace MySQL queries even when USDT probes aren't enabled on the MySQL server, which is so clutch 🫶
• -m THRESHOLD — the minimum query latency (duration) to trace, in milliseconds ⏱️ the default is 1 ms 💖
• {mysql,postgres} — the database engine you want to trace 🐬🐘

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🍓 EXAMPLES 🍓

trace MySQL server queries slower than 1 ms:

# dbslower mysql

trace queries slower than 10 ms for PostgreSQL in process 408:

# dbslower postgres -p 408 -m 10

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🦋 FIELDS 🦋

• TIME(s) — when the query started, in seconds ⏰
• PID — process ID of the traced server 🆔
• MS — how many milliseconds the query took, from start to end 🕐
• QUERY — the query string, truncated to 256 characters ✂️

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🌈 OVERHEAD 🌈

this adds low-overhead instrumentation to queries, and it only sends output data from the kernel up to user level if a query goes over the threshold 🧠 if the server's query rate is less than 1,000/sec, the overhead is expected to be negligible 😌 if the query rate is higher, test it out to gauge the overhead yourself 🔥

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🔗 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 📖✨

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🖥️ OS 🖥️

Linux 🐧

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🚧 STABILITY 🚧

Unstable - in development. so it's still a work in progress, bestie 🛠️

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👑 AUTHOR 👑

Sasha Goldshtein, Brendan Gregg 🫶

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🔮 SEE ALSO 🔮

biosnoop(8), mysqld_qslower(8), dbstat(8) 💜

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okay that's the whole tea ☕💖 this page is from the USER COMMANDS section, dated 2017-02-15, and it's all about dbslower(8) 🎀 stay hydrated, stay root, and go trace those slow queries bestie 💅🌸