bionic (8) dbslower-bpfcc.8.gz

NAME

       dbslower - Trace MySQL/PostgreSQL server queries slower than a threshold.

SYNOPSIS

       dbslower [-v] [-p PID [PID ...]] [-m THRESHOLD] {mysql,postgres}

DESCRIPTION

       This traces queries served by a MySQL or PostgreSQL server, and prints those that exceed a latency (query
       time) threshold. By default a threshold of 1 ms is used.

       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 1 ms.

       {mysql,postgres}
              The database engine to trace.

EXAMPLES

       Trace MySQL server queries slower than 1 ms:
              # dbslower mysql

       Trace slower than 10 ms for PostgreSQL in process 408:
              # dbslower postgres -p 408 -m 10

FIELDS

       TIME(s)
              Time of query start, in seconds.

       PID    Process ID of the traced server.

       MS     Milliseconds for the query, from start to end.

       QUERY  Query string, truncated to 256 characters.

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.

AUTHOR

       Sasha Goldshtein, Brendan Gregg

SEE ALSO

       biosnoop(8), mysqld_qslower(8), dbstat(8)