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.  Alternativly, MySQL
21       queries can be traced without the USDT support using the -x option.
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23       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

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

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

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

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

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

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

81       Linux
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STABILITY

84       Unstable - in development.
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AUTHOR

87       Sasha Goldshtein, Brendan Gregg
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