POSTGRES(1) PostgreSQL Server Applications POSTGRES(1)NAMEpostgres - run a PostgreSQL server in single-user mode
SYNOPSISpostgres [ -A 0 | 1 ] [ -B nbuffers ] [ -c name=value ]
[ -d debug-level ] [ -D datadir ] [ -e ] [ -E ] [ -f s |
i | t | n | m | h ] [ -F ] [ -i ] [ -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 ] [ -i ] [ -o filename ] [ -O ] [ -p
database ] [ -P ] [ -s | -t pa | pl | ex ] [ -S sort-mem
] [ -v protocol-version ] [ -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 postmaster(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 pri-
mary use for this mode is during bootstrapping by
initdb(1). Sometimes 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 running a single-user back-
end is not truly suitable for debugging the server since
no realistic interprocess communication and locking will
happen.
When running a stand-alone backend, the session user will
be set to the user with ID 1. This user does not actually
have to exist, so a stand-alone backend 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 inher-
its 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
configuration file. See the Administrator's Guide for
details. Some (safe) options can also be set from the con-
necting client in an application-dependent way. For exam-
ple, 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 pre-
vents the debugging level of the postmaster from being
propagated to the backend.
-e Sets the default date style to ``European'', which
means that the ``day before month'' (rather than
month before day) rule is used to interpret ambigu-
ous date input, and that the day is printed before
the month in certain date output formats. See the
PostgreSQL User's Guide for more information.
-o filename
Sends all debugging and error output to filename.
If the backend is running under the postmaster,
this option is ignored, and the stderr inherited
from the postmaster is used.
-P Ignore system indexes while scanning/updating sys-
tem tuples. The REINDEX command for system
tables/indexes requires this option to be used.
-s Print time information and other statistics at the
end of each query. 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 inter-
nal sorts and hashes before resorting to temporary
disk files. The value is specified in kilobytes,
and defaults to 512 kilobytes. Note that for a com-
plex 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 queries.
-N Disables use of newline as a query 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 PostgreSQL system developers. Use of
any of these options is highly discouraged. 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 meth-
ods: 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 disabled completely; the -fs and -fn
options simply discourage the optimizer from using
those plan types if it has any other alternative.
-i Prevents query execution, but shows the plan tree.
-O Allows the structure of system tables to be modi-
fied. This is used by initdb.
-p database
Indicates that this server has been started by a
postmaster and makes different assumptions about
buffer pool management, file descriptors, etc.
-t pa[rser] | pl[anner] | e[xecutor]
Print timing statistics for each query relating to
each of the major system modules. This option can-
not be used together with the -s option.
-v protocol
Specifies the version number of the frontend/back-
end protocol to be used for this particular ses-
sion.
-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
backend process.
ENVIRONMENT
PGDATA Default data direction location
For others, which have little influence during single-user
mode, see postmaster(1).
NOTES
To stop a running query use the SIGINT signal. To tell
postgres to reread the config file, use a SIGHUP signal.
The postmaster uses SIGTERM to tell a postgres process to
quit normally and SIGQUIT to terminate without the normal
cleanup. These should not be used by users.
USAGE
Start a stand-alone backend with a command like
postgres-D $PGDATA other-options my_database
Provide the correct path to the database area 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 backend 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 backslash just before
each newline except the last one.
But if you use the -N command line switch, then newline
does not terminate command entry. The backend will read
the standard input until the end-of-file (EOF) marker,
then process the input as a single query string. Back-
slash-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 backend does not provide sophis-
ticated line-editing features (no command history, for
example).
SEE ALSOinitdb(1), ipcclean(1), postmaster(1)Application 2002-11-22 POSTGRES(1)
