dbstat-bpfcc8
Collect histograms of mysql/postgresql query latencies.
Usage
dbstat [-v]
[-p
PID
[PID ...]]
[-m
THRESHOLD]
[-u]
[-i
INTERVAL]
mysql,postgres
Overview
This traces queries served by a MySQL or PostgreSQL server, and collects a histogram of query latencies. The histogram is printed at the end of collection, or at specified intervals.
This uses User Statically-Defined Tracing (USDT) probes, a feature added to MySQL and PostgreSQL for DTrace support, but which may not be enabled on a given installation. See requirements.
Since this uses BPF, only the root user can use this tool.
Requirements
CONFIG_BPF, bcc, and MySQL server with USDT probe support (when configuring the build: -DENABLE_DTRACE=1) or PostgreSQL server with USDT probe support (when configuring the build: --enable-dtrace).
Options
-h Print usage message.
-
-p PID -
Trace this PID. If no PID is specified, the tool will attempt to automatically detect the MySQL or PostgreSQL processes running on the system.
-
-m THRESHOLD -
Minimum query latency (duration) to trace, in milliseconds. Default is all queries.
-
-u -
Display query latencies in microseconds (default: milliseconds).
-
-i INTERVAL -
Print summaries (histograms) at this interval, specified in seconds.
- {mysql,postgres}
-
The database engine to trace.
Examples
Display histogram of MySQL query latencies:
|
# dbstat mysql |
|---|---|
Display histogram of PostgreSQL query latencies slower than 10ms in pid 408:
|
# dbstat postgres -p 408 -m 10 |
Display histogram of PostgreSQL query latencies at 3-second intervals:
|
# dbstat postgres -i 3 |
Overhead
This adds low-overhead instrumentation to 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
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
Linux
Stability
Unstable - in development.
Releases
Unchanged in 4 releases since Debian 10 (Buster).