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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
] [ -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 primary
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
backend 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 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 configuration
file. See the Administrator's Guide 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 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 ambiguous 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 system 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 internal sorts and hashes
before resorting to temporary disk files. The value is specified in
kilobytes, and defaults to 512 kilobytes. 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 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 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 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 modified. 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 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 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.
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 backend does not provide sophisticated line-
editing features (no command history, for example).
SEE ALSO
initdb(1), ipcclean(1), postmaster(1)
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