|mysqld_qslower(8)||System Manager's Manual||mysqld_qslower(8)|
mysqld_qslower - Trace MySQL server queries slower than a threshold.
mysqld_qslower PID [min_ms]
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.
CONFIG_BPF, bcc, and MySQL server with USDT probe support (when configuring the build: -DENABLE_DTRACE=1).
PID Trace this mysqld PID.
- Minimum query latency (duration) to trace, in milliseconds. Default is 1 ms.
- Trace MySQL server queries slower than 1 ms for PID 1981:
- # mysqld_qslower 1981
- Trace slower than 10 ms for PID 1981:
- # mysqld_qslower 1981 10
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.
This is from bcc.
Also look in the bcc distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool.
Unstable - in development.