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 ...]] [-m THRESHOLD] {mysql,postgres}
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DESCRIPTION

13       This traces queries served by a MySQL or PostgreSQL server, and  prints
14       those  that  exceed  a  latency  (query  time)  threshold. By default a
15       threshold of 1 ms is used.
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17       This uses User Statically-Defined  Tracing  (USDT)  probes,  a  feature
18       added  to MySQL and PostgreSQL for DTrace support, but which may not be
19       enabled on a given installation. See requirements.
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21       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

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

29       -h Print usage message.
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31       -p PID Trace this PID. If no PID is specified, the tool will attempt to
32              automatically  detect  the MySQL or PostgreSQL processes running
33              on the system.
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35       -m THRESHOLD
36              Minimum query latency  (duration)  to  trace,  in  milliseconds.
37              Default is 1 ms.
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39       {mysql,postgres}
40              The database engine to trace.
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EXAMPLES

43       Trace MySQL server queries slower than 1 ms:
44              # dbslower mysql
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46       Trace slower than 10 ms for PostgreSQL in process 408:
47              # dbslower postgres -p 408 -m 10
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FIELDS

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

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

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

75       Linux
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STABILITY

78       Unstable - in development.
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AUTHOR

81       Sasha Goldshtein, Brendan Gregg
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