Ubuntu Manpage: pg_top - display and update information about the top cpu PostgreSQL processes

NAME

       pg_top - display and update information about the top cpu PostgreSQL processes

SYNOPSIS

       pg_top [option...] [number]

DESCRIPTION

       pg_top  displays  the  top  processes  on  the system and periodically updates this information.  Raw cpu
       percentage is used to rank the processes.  If number is given, then the  top  number  processes  will  be
       displayed instead of the default.

       pg_top  makes  a  distinction between terminals that support advanced capabilities and those that do not.
       This distinction affects the choice of defaults for certain options.  In the remainder of this  document,
       an "intelligent" terminal is one that supports cursor addressing, clear screen, and clear to end of line.
       Conversely,  a *(lqdumb*(rq terminal is one that does not support such features.  If the output of pg_top
       is redirected to a file, it acts as if it were being run on a dumb terminal.

OPTIONS

-b, --batch
Use "batch" mode. In this mode, all input from the terminal is ignored. Interrupt characters
(such as ^C and ^e) still have an effect. This is the default on a dumb terminal, or when the
output is not a terminal.

-C, --color-mode
Turn off the use of color in the display.

-c, --show-command
Show the command name for each process. Default is to show the full command line. This option is
not supported on all platforms.

-h HOST, --host=HOST
Specifies the host name of the machine on which the server is running. If the value begins with a
slash, it is used as the directory for the Unix domain socket. The default is taken from the
PGHOST environment variable, if set.

-I, --hide-idle
Do not display idle processes. By default, pg_top displays both active and idle processes.

-i, --interactive
Use "lqinteractive" mode. In this mode, any input is immediately read for processing. See the
section on "Interactive Mode" for an explanation of which keys perform what functions. After the
command is processed, the screen will immediately be updated, even if the command was not
understood. This mode is the default when standard output is an intelligent terminal.

-n, --non-interactive
Use "non-interactive" mode. This is identical to "batch" mode.

-o FIELD, --order-field=FIELD
Sort the process display area on the specified field. The field name is the name of the column as
seen in the output, but in lower case. Likely values are "cpu", "size", "res", "xtime" and
"qtime", but may vary on different operating systems. Note that not all operating systems support
this option.

-p PORT, --port=PORT
Specifies the TCP port or local Unix domain socket file extension on which the server is listening
for connections. Defaults to the PGPORT environment variable, if set.

-R Display WAL sender processes' replication activity to connected standby servers. Only directly
connected standbys are listed; no information is available about downstream standby servers.

-r, --remote-mode
Monitor a remote database where the database is on a system other than where pg_top is running
from. pg_top will monitor a remote database if it has the pg_proctab extension installed.

-s TIME, --set-delay=TIME
Set the delay between screen updates to TIME seconds. The default delay between updates is 5
seconds.

-T, --show-tags
List all available color tags and the current set of tests used for color highlighting, then exit.

-U USERNAME, --username=USERNAME
PostgreSQL database user name to connect as.

-V, --version
Write version number information to stderr then exit immediately. No other processing takes place
when this option is used. To see current revision information while pg_top is running, use the
help command "?".

-W, --password
Forces pg_top to prompt for a password before connecting to a database. pg_top will also keep the
database connection open while running, and will clear the database connection from memory for
security.

-X Display I/O activity per process. This depends on whether the platform pg_top is run on supports
getting I/O statistics per process, or whether the database system that pg_proctab is installed on
supports getting I/O statistics when pg_top attempts to get operating system statistics remotely.

-x COUNT, --set-display=COUNT
Show only COUNT displays, then exit. A display is considered to be one update of the screen.
This option allows the user to select the number of displays he wants to see before pg_top
automatically exits. For intelligent terminals, no upper limit is set. The default is 1 for dumb
terminals.

-z USERNAME, --show-username=USERNAME
Show only those processes owned by USERNAME. This option currently only accepts PostgreSQL
database user names.

Both COUNT and NUMBER fields can be specified as "infinite", indicating that they can stretch as far as
possible. This is accomplished by using any proper prefix of the keywords "infinity", "maximum, or
"all". The default for COUNT on an intelligent terminal is, in fact, infinity.

The environment variable PG_TOP is examined for options before the command line is scanned. This enables
a user to set his or her own defaults. The number of processes to display can also be specified in the
environment variable PG_TOP. The options -C, -I, and -u are actually toggles. A second specification of
any of these options will negate the first. Thus a user who has the environment variable PG_TOP set to
"-I" may use the command "top -I" to see idle processes.

INTERACTIVE MODE

When pg_top is running in "interactive mode", it reads commands from the terminal and acts upon them
accordingly. In this mode, the terminal is put in "BREAK", so that a character will be processed as soon
as it is typed. Almost always, a key will be pressed when pg_top is between displays; that is, while it
is waiting for TIME seconds to elapse. If this is the case, the command will be processed and the
display will be updated immediately thereafter (reflecting any changes that the command may have
specified). This happens even if the command was incorrect. If a key is pressed while pg_top is in the
middle of updating the display, it will finish the update and then process the command. Some commands
require additional information, and the user will be prompted accordingly. While typing this information
in, the user's erase and kill keys (as set up by the command stty) are recognized, and a newline
terminates the input.

These commands are currently recognized (^L refers to control-L):

^L Redraw the screen.

A Display the actual query plan (EXPLAIN ANALYZE) of the currently running SQL statement by
re-running the SQL statement (prompt for process id.)

a Display the top PostgreSQL processor activity. (default)

C Toggle the use of color in the display.

c Toggle the display of the full command line.

d Change the number of displays to show (prompt for new number). Remember that the next display
counts as one, so typing d1 will make pg_top show one final display and then immediately exit.

h or ? Display a summary of the commands (help screen). Version information is included in this display.

E Display re-determined execution plan (EXPLAIN) of the SQL statement by a backend process (prompt
for process id.)

i Toggle the display of idle processes.

L Display the currently held locks by a backend process (prompt for process id.)

n or # Change the number of processes to display (prompt for new number).

o Change the order in which the display is sorted. This command is not available on all systems.
The sort key names when viewing processes vary from system to system but usually include: "cpu",
"res", "size", "xtime" and "qtime". The default is unsorted. See the interactive help for
available sort key names.

Q Display the currently running query of a backend process (prompt for process id.)

q Quit pg_top.

s Change the number of seconds to delay between displays (prompt for new number).

u Display only processes owned by a specific username (prompt for username). If the username
specified is simply *(lq+*(rq, then processes belonging to all users will be displayed.

THE DISPLAY

       The actual display varies depending on the specific variant of Unix that the machine  is  running.   This
       description may not exactly match what is seen by pg_top running on this particular machine.  Differences
       are listed at the end of this manual entry.

       The  top  few  lines of the display show general information about the state of the system, including the
       last process id assigned to a process (on most systems), the three load averages, the current  time,  the
       number  of  existing  processes,  the  number  of  processes  in each state (sleeping, running, starting,
       zombies, and stopped), and a percentage of time spent in  each  of  the  processor  states  (user,  nice,
       system, and idle).  It also includes information about physical and virtual memory allocation.

       The  remainder of the screen displays information about individual processes.  This display is similar in
       spirit to ps(1) but it is not exactly the same.  The columns displayed by  pg_top  will  differ  slightly
       between operating systems.  Generally, the following display are available:

ACTIVITY DISPLAY

       PID    The process id.

       USERNAME
              Username  of  the  process's  owner  (if  -u  is  specified,  a UID column will be substituted for
              USERNAME).

       SIZE   Total size of the process (text, data, and stack) given in kilobytes.

       RES    Resident memory: current amount of process memory  that  resides  in  physical  memory,  given  in
              kilobytes.

       STATE  Current backend state (typically one of "idle", "active", "idltxn", "fast", "disable", or "stop".

       XTIME  Elapsed time since the current transactions started.

       QTIME  Elapsed time since the current query started.

       %CPU   Percentage of available cpu time used by this process.

       LOCKS  Number of locks granted to this process.

       COMMAND
              Name of the command that the process is currently running.

I/O DISPLAY (LINUX ONLY)

       PID    The process id.

       IOPS   Count the number of read and write I/O operations per second.

       IORPS  Count the number of read I/O operations per second.

       IOWPS  Count the number of write I/O operations per second.

       READS  Number of bytes read from storage.

       WRITES Number of bytes written to storage.

       COMMAND
              Name of the command that the process is currently running.

REPLICATION DISPLAY

       PID    The process id.

       USERNAME
              Name of the user logged into this WAL sender process

       APPLICATION
              Name of the application that is connected to this WAL sender

       CLIENT IP address of the client connected to this WAL sender

       STATE  Current WAL sender state

       PRIMARY
              Current transaction log insert location on primary node

       SENT   Last write-ahead log location sent on this connection

       WRITE  Last write-ahead log location written to disk

       FLUSH  Last write-ahead log location flushed to disk

       REPLAY Last write-ahead log location replayed into the database

       SLAG   Size of write-ahead log location remaining to be sent

       WLAG   Size of write-ahead log location remaining to be written to disk

       FLAG   Size of write-ahead log location remaining to be flushed to disk

       RLAG   Size of write-ahead log location remaining to be replayed into the database

COLOR

pg_top supports the use of ANSI color in its output. By default, color is available but not used. The
environment variable PG_TOPCOLORS specifies colors to use and conditions for which they should be used.
At the present time, only numbers in the summary display area can be colored. In a future version it will
be possible to highlight numbers in the process display area as well. The environment variable is the
only way to specify color: there is no equivalent command line option. Note that the environment
variable PG_TOPCOLOURS is also understood. The British spelling takes precedence. The use of color only
works on terminals that understand and process ANSI color escape sequences.

The environment variable is a sequence of color specifications, separated by colons. Each specification
takes the form tag=min,max#code where tag is the name of the value to check, min and max specify a range
for the value, and code is an ANSI color code. Multiple color codes can be listed and separated with
semi-colons. A missing min implies the lowest possible value (usually 0) and a missing max implies
infinity. The comma must always be present. When specifying numbers for load averages, they should be
multiplied by 100. For example, the specification 1min=500,1000#31 indicates that a 1 minute load
average between 5 and 10 should be displayed in red. Color attributes can be combined. For example, the
specification 5min=1000,#37;41 indicates that a 5 minute load average higher than 10 should be displayed
with white characters on a red background. A special tag named header is used to control the color of the
header for process display. It should be specified with no lower and upper limits, specifically
header=,# followed by the ANSI color code.

You can see a list of color codes recognized by this installation of pg_top with the -T option. This
will also show the current set of tests used for color highligting, as specified in the environment.

ENVIRONMENT

       PG_TOP              user-configurable defaults for options.  PG_TOPCOLORS color specification

BUGS

       As with ps(1), things can change while pg_top is collecting information for an update.   The  picture  it
       gives is only a close approximation to reality.

LINUX NOTES

       The Linux port was written by Richard Henderson <rth@tamu.edu>.  The CPU% calculation was brazenly stolen
       from the Solaris 2 port and should be attributed to one of the many names listed in its man page.

       The order support was stolen from SUNOS 5 port by Alexey Klimkin <kad@klon.tme.mcst.ru>

       Made to work under 2.4 by William LeFebvre.

AUTHOR

       William LeFebvre, Mark Wong

4.0.0                                                                                                  PG_TOP(1)