bcc-dbstat(8)

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

6       dbstat - Collect histograms of MySQL/PostgreSQL query latencies.
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SYNOPSIS

9       dbstat  [-v]  [-p  PID  [PID  ...]]  [-m  THRESHOLD] [-u] [-i INTERVAL]
10       {mysql,postgres}
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DESCRIPTION

13       This traces queries served by a MySQL or PostgreSQL  server,  and  col‐
14       lects  a  histogram of query latencies. The histogram is printed at the
15       end of collection, or at specified intervals.
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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 all queries.
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39       -u     Display query latencies in microseconds (default: milliseconds).
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41       -i INTERVAL
42              Print summaries (histograms) at this interval, specified in sec‐
43              onds.
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45       {mysql,postgres}
46              The database engine to trace.
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EXAMPLES

49       Display histogram of MySQL query latencies:
50              # dbstat mysql
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52       Display histogram of PostgreSQL query latencies slower than 10ms in pid
53       408:
54              # dbstat postgres -p 408 -m 10
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56       Display histogram of PostgreSQL query latencies at 3-second intervals:
57              # dbstat postgres -i 3
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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
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