bcc-dbslower(8)

1dbslower(8)                 System Manager's Manual                dbslower(8)
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NAME

6       dbslower  - Trace MySQL/PostgreSQL server queries slower than a thresh‐
7       old.
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SYNOPSIS

10       dbslower [-v] [-p PID [PID ...]] [-x PATH] [-m THRESHOLD]  {mysql,post‐
11       gres}
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DESCRIPTION

14       This  traces queries served by a MySQL or PostgreSQL server, and prints
15       those that exceed a  latency  (query  time)  threshold.  By  default  a
16       threshold of 1 ms is used.
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18       This  uses  User  Statically-Defined  Tracing  (USDT) probes, a feature
19       added to MySQL and PostgreSQL for DTrace support, but which may not  be
20       enabled  on  a  given  installation.  See requirements.  Alternatively,
21       MySQL queries can be traced without  the  USDT  support  using  the  -x
22       option.
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24       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

27       CONFIG_BPF, bcc, and MySQL server with USDT probe support (when config‐
28       uring the build: -DENABLE_DTRACE=1)  or  PostgreSQL  server  with  USDT
29       probe support (when configuring the build: --enable-dtrace).
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OPTIONS

32       -h Print usage message.
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34       -p PID Trace this PID. If no PID is specified, the tool will attempt to
35              automatically detect the MySQL or PostgreSQL  processes  running
36              on the system.
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38       -x PATH
39              Path  to  MySQL  binary. This option allow to MySQL queries even
40              when USDT probes aren't enabled on the MySQL server.
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42       -m THRESHOLD
43              Minimum query latency  (duration)  to  trace,  in  milliseconds.
44              Default is 1 ms.
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46       {mysql,postgres}
47              The database engine to trace.
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EXAMPLES

50       Trace MySQL server queries slower than 1 ms:
51              # dbslower mysql
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53       Trace slower than 10 ms for PostgreSQL in process 408:
54              # dbslower postgres -p 408 -m 10
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FIELDS

57       TIME(s)
58              Time of query start, in seconds.
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60       PID    Process ID of the traced server.
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62       MS     Milliseconds for the query, from start to end.
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64       QUERY  Query string, truncated to 256 characters.
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OVERHEAD

67       This  adds low-overhead instrumentation to queries, and only emits out‐
68       put data from kernel to user-level if they query exceeds the threshold.
69       If  the  server  query  rate  is  less  than 1,000/sec, the overhead is
70       expected to be negligible. If the query rate is higher, test  to  gauge
71       overhead.
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SOURCE

74       This is from bcc.
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76              https://github.com/iovisor/bcc
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78       Also  look  in  the bcc distribution for a companion _examples.txt file
79       containing example usage, output, and commentary for this tool.
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OS

82       Linux
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STABILITY

85       Unstable - in development.
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AUTHOR

88       Sasha Goldshtein, Brendan Gregg
89