NAME
pg_top - display and update information about the top cpu PostgreSQL
processes
SYNOPSIS
pg_top [ -ITWbcinqu ] [ -dDBNAME ] [ -hHOSTNAME ] [ -ofield ] [ -pPORT
] [ -stime ] [ -UUSER ] [ -xcount ] [ -zusername ] [ 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
"dumb" 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
-C Turn off the use of color in the display.
-I Do not display idle processes. By default, pg_top displays both
active and idle processes.
-T List all available color tags and the current set of tests used
for color highlighting, then exit.
-W Forces pg_top to prompt for a password before connecting to a
database.
-b Use "batch" mode. In this mode, all input from the terminal is
ignored. Interrupt characters (such as ^C and ^\) still have an
effect. This is the default on a dumb terminal, or when the
output is not a terminal.
-c Show the command name for each process. Default is to show the
full command line. This option is not supported on all
platforms.
-i Use "interactive" 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 Use "non-interactive" mode. This is indentical to "batch" mode.
-q Renice pg_top to -20 so that it will run faster. This can be
used when the system is being very sluggish to improve the
possibility of discovering the problem. This option can only be
used by root.
-u Do not take the time to map uid numbers to usernames. Normally,
pg_top will read as much of the file "/etc/passwd" as is
necessary to map all the user id numbers it encounters into
login names. This option disables all that, while possibly
decreasing execution time. The uid numbers are displayed
instead of the names.
-v 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 "?".
-stime Set the delay between screen updates to time seconds. The
default delay between updates is 5 seconds.
-ofield
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", and "time",
but may vary on different operating systems. Note that not all
operating systems support this option.
-xcount
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.
-zusername
Show only those processes owned by username. This option
currently only accepts usernames and will not understand uid
numbers.
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 "CBREAK", 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.)
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.)
e Display a list of system errors (if any) generated by the last
kill or renice command.
i (or I) Toggle the display of idle processes.
k Send a signal ("kill" by default) to a list of processes. This
acts similarly to the command kill(1)).
L Display the currently held locks by a backend process (prompt
for process id.)
M Order by memory utilization.
N Sort by 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 fron system to system but usually
include: "cpu", "res", "size", "time". The default is cpu.
When viewing user table statistics: "seq_scan", "seq_tup_read",
"idx_scan", "idx_tup_fetch", "n_tup_ins", "n_tup_upd",
"n_tup_del". The default is seq_scan. When viewing user index
statistics: "idx_scan", "idx_tup_fetch", "idx_tup_read". The
default is idx_scan.
P Sort by processor utilization.
Q Display the currently running query of a backend process (prompt
for process id.)
q Quit pg_top.
R Display user table statistics.
r Change the priority (the "nice") of a list of processes. This
acts similarly to the command renice(8)).
s Change the number of seconds to delay between displays (prompt
for new number).
T Order by time.
t Toggle between cumulative or differential statistics when
viewing user table or user index statistics.
u Display only processes owned by a specific username (prompt for
username). If the username specified is simply "+", then
processes belonging to all users will be displayed.
X Display user index statistics.
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 fields are
displayed:
PID The process id.
USERNAME
Username of the process’s owner (if -u is specified, a UID
column will be substituted for USERNAME).
PRI Current priority of the process.
NICE Nice amount in the range -20 to 20, as established by the use of
the command nice.
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 state (typically one of "sleep", "run", "idl", "zomb",
or "stop").
TIME Number of system and user cpu seconds that the process has used.
CPU Percentage of available cpu time used by this process.
COMMAND
Name of the command that the process is currently running.
COLOR
pg_top supports the use of ANSI color in its output. By default, color
is available but not used. The environment variable TOPCOLORS
specifies colors to use and conditions for which they should be used.
At the present time, only numbers in the summay 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 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.
AUTHOR
William LeFebvre Mark Wong
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.
SEE ALSO
kill(1), ps(1), stty(1), mem(4), renice(8)
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.