postgres(1)
NAME
postgres - run a PostgreSQL server in single-user mode
SYNOPSIS
postgres [ -A 0 | 1 ] [ -B nbuffers ] [ -c name=value ] [ -d debug-
level ] [ --describe-config ] [ -D datadir ] [ -e ] [ -E ] [ -f s | i
| t | n | m | h ] [ -F ] [ -N ] [ -o filename ] [ -O ] [ -P ] [ -s | -t
pa | pl | ex ] [ -S sort-mem ] [ -W seconds ] [ --name=value ] database
postgres [ -A 0 | 1 ] [ -B nbuffers ] [ -c name=value ] [ -d debug-
level ] [ -D datadir ] [ -e ] [ -f s | i | t | n | m | h ] [ -F ] [ -o
filename ] [ -O ] [ -p database ] [ -P ] [ -s | -t pa | pl | ex ] [ -S
sort-mem ] [ -v protocol ] [ -W seconds ] [ --name=value ]
DESCRIPTION
The postgres executable is the actual PostgreSQL server process that
processes queries. It is normally not called directly; instead a post-
master(1) multiuser server is started.
The second form above is how postgres is invoked by the postmaster(1)
(only conceptually, since both postmaster and postgres are in fact the
same program); it should not be invoked directly this way. The first
form invokes the server directly in interactive single-user mode. The
primary use for this mode is during bootstrapping by initdb(1). Some-
times it is used for debugging or disaster recovery.
When invoked in interactive mode from the shell, the user can enter
queries and the results will be printed to the screen, but in a form
that is more useful for developers than end users. But note that run-
ning a single-user server is not truly suitable for debugging the
server since no realistic interprocess communication and locking will
happen.
When running a stand-alone server, the session user will be set to the
user with ID 1. This user does not actually have to exist, so a stand-
alone server can be used to manually recover from certain kinds of
accidental damage to the system catalogs. Implicit superuser powers are
granted to the user with ID 1 in stand-alone mode.
OPTIONS
When postgres is started by a postmaster(1) then it inherits all
options set by the latter. Additionally, postgres-specific options can
be passed from the postmaster with the -o switch.
You can avoid having to type these options by setting up a configura-
tion file. See the section called ``Run-time Configuration'' in the
documentation for details. Some (safe) options can also be set from the
connecting client in an application-dependent way. For example, if the
environment variable PGOPTIONS is set, then libpq-based clients will
pass that string to the server, which will interpret it as postgres
command-line options.
GENERAL PURPOSE
The options -A, -B, -c, -d, -D, -F, and --name have the same meanings
as the postmaster(1) except that -d 0 prevents the server log level of
the postmaster from being propagated to postgres.
-e Sets the default date style to ``European'', that is DMY order-
ing of input date fields. This also causes the day to be printed
before the month in certain date output formats. See the sec-
tion called ``Date/Time Types'' in the documentation for more
information.
-o filename
Send all server log output to filename. If postgres is running
under the postmaster, this option is ignored, and the stderr
inherited from the postmaster is used.
-P Ignore system indexes when reading system tables (but still
update the indexes when modifying the tables). This is useful
when recovering from damaged system indexes.
-s Print time information and other statistics at the end of each
command. This is useful for benchmarking or for use in tuning
the number of buffers.
-S sort-mem
Specifies the amount of memory to be used by internal sorts and
hashes before resorting to temporary disk files. The value is
specified in kilobytes, and defaults to 1024. Note that for a
complex query, several sorts and/or hashes might be running in
parallel, and each one will be allowed to use as much as sort-
mem kilobytes before it starts to put data into temporary files.
OPTIONS FOR STAND-ALONE MODE
database
Specifies the name of the database to be accessed. If it is
omitted it defaults to the user name.
-E Echo all commands.
-N Disables use of newline as a statement delimiter.
SEMI-INTERNAL OPTIONS
There are several other options that may be specified, used mainly for
debugging purposes. These are listed here only for the use by Post-
greSQL system developers. Use of any of these options is highly dis-
couraged. Furthermore, any of these options may disappear or change in
a future release without notice.
-f { s | i | m | n | h }
Forbids the use of particular scan and join methods: s and i
disable sequential and index scans respectively, while n, m, and
h disable nested-loop, merge and hash joins respectively.
Note: Neither sequential scans nor nested-loop joins can be dis-
abled completely; the -fs and -fn options simply discourage the
optimizer from using those plan types if it has any other alter-
native.
-O Allows the structure of system tables to be modified. This is
used by initdb.
-p database
Indicates that this process has been started by a postmaster and
specifies the database to use. etc.
-t pa[rser] | pl[anner] | e[xecutor]
Print timing statistics for each query relating to each of the
major system modules. This option cannot be used together with
the -s option.
-v protocol
Specifies the version number of the frontend/backend protocol to
be used for this particular session.
-W seconds
As soon as this option is encountered, the process sleeps for
the specified amount of seconds. This gives developers time to
attach a debugger to the server process.
--describe-config
This option dumps out the server's internal configuration vari-
ables, descriptions, and defaults in tab-delimited COPY format.
It is designed primarily for use by administration tools.
ENVIRONMENT
PGDATA Default data direction location
For others, which have little influence during single-user mode, see
postmaster(1).
NOTES
To cancel a running query, send the SIGINT signal to the postgres
process running that command.
To tell postgres to reload the configuration files, send a SIGHUP sig-
nal. Normally it's best to SIGHUP the postmaster instead; the postmas-
ter will in turn SIGHUP each of its children. But in some cases it
might be desirable to have only one postgres process reload the config-
uration files.
The postmaster uses SIGTERM to tell a postgres process to quit normally
and SIGQUIT to terminate without the normal cleanup. These signals
should not be used by users. It is also unwise to send SIGKILL to a
postgres process --- the postmaster will interpret this as a crash in
postgres, and will force all the sibling postgres processes to quit as
part of its standard crash-recovery procedure.
USAGE
Start a stand-alone server with a command like
postgres -D /usr/local/pgsql/data other-options my_database
Provide the correct path to the database directory with -D, or make
sure that the environment variable PGDATA is set. Also specify the
name of the particular database you want to work in.
Normally, the stand-alone server treats newline as the command entry
terminator; there is no intelligence about semicolons, as there is in
psql. To continue a command across multiple lines, you must type back-
slash just before each newline except the last one.
But if you use the -N command line switch, then newline does not termi-
nate command entry. In this case, the server will read the standard
input until the end-of-file (EOF) marker, then process the input as a
single command string. Backslash-newline is not treated specially in
this case.
To quit the session, type EOF (Control+D, usually). If you've used -N,
two consecutive EOFs are needed to exit.
Note that the stand-alone server does not provide sophisticated line-
editing features (no command history, for example).
SEE ALSO
initdb(1), ipcclean(1), postmaster(1)
Application 2003-11-02 POSTGRES(1)
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