trusty (1) postgres.1.gz

Provided by: postgres-xc_1.1-2ubuntu2_amd64 bug

NAME

       postgres - Postgres-XC database server

SYNOPSIS

       postgres [option...]

DESCRIPTION

           Note
           The following description applies both to Postgres-XC and PostgreSQL if not described explicitly.

       postgres is the Postgres-XC database server. In order for a client application to access a database it
       connects (over a network or locally) to a running postgres instance. The postgres instance then starts a
       separate server process to handle the connection.

       One postgres instance always manages the data of exactly one database cluster. A database cluster is a
       collection of databases that is stored at a common file system location (the “data area”). More than one
       postgres instance can run on a system at one time, so long as they use different data areas and different
       communication ports (see below). When postgres starts it needs to know the location of the data area. The
       location must be specified by the -D option or the PGDATA environment variable; there is no default.
       Typically, -D or PGDATA points directly to the data area directory created by initdb(1). Other possible
       file layouts are discussed in Section 17.2, “File Locations”, in the documentation.

       By default postgres starts in the foreground and prints log messages to the standard error stream. In
       practical applications postgres should be started as a background process, perhaps at boot time.

       The postgres command can also be called in single-user mode. The primary use for this mode is during
       bootstrapping by initdb(1). Sometimes it is used for debugging or disaster recovery; note that running a
       single-user server is not truly suitable for debugging the server, since no realistic interprocess
       communication and locking will happen. When invoked in single-user 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. In the single-user mode, the session user will be set to the user with ID 1,
       and implicit superuser powers are granted to this user. This user does not actually have to exist, so the
       single-user mode can be used to manually recover from certain kinds of accidental damage to the system
       catalogs.

OPTIONS

       postgres accepts the following command-line arguments. For a detailed discussion of the options consult
       Chapter 17, Coordinator and Datanode Configuration, in the documentation. You can save typing most of
       these options by setting up a configuration file. Some (safe) options can also be set from the connecting
       client in an application-dependent way to apply only for that session. 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
       -A 0|1
           Enables run-time assertion checks, which is a debugging aid to detect programming mistakes. This
           option is only available if assertions were enabled when Postgres-XC was compiled. If so, the default
           is on.

       -B nbuffers
           Sets the number of shared buffers for use by the server processes. The default value of this
           parameter is chosen automatically by initdb. Specifying this option is equivalent to setting the
           shared_buffers configuration parameter.

       -c name=value
           Sets a named run-time parameter. The configuration parameters supported by Postgres-XC are described
           in Chapter 17, Coordinator and Datanode Configuration, in the documentation. Most of the other
           command line options are in fact short forms of such a parameter assignment.  -c can appear multiple
           times to set multiple parameters.

       -C name
           Prints the value of the named run-time parameter, and exits. (See the -c option above for details.)
           This can be used on a running server, and returns values from postgresql.conf, modified by any
           parameters supplied in this invocation. It does not reflect parameters supplied when the cluster was
           started.

           This option is meant for other programs that interact with a server instance, such as pg_ctl(1), to
           query configuration parameter values. User-facing applications should instead use SHOW(7) or the
           pg_settings view.

       -d debug-level
           Sets the debug level. The higher this value is set, the more debugging output is written to the
           server log. Values are from 1 to 5. It is also possible to pass -d 0 for a specific session, which
           will prevent the server log level of the parent postgres process from being propagated to this
           session.

       -D datadir
           Specifies the file system location of the data directory or configuration file(s). See Section 17.2,
           “File Locations”, in the documentation for details.

       -e
           Sets the default date style to “European”, that is DMY ordering of input date fields. This also
           causes the day to be printed before the month in certain date output formats. See Section 8.5,
           “Date/Time Types”, in the documentation for more information.

       -F
           Disables fsync calls for improved performance, at the risk of data corruption in the event of a
           system crash. Specifying this option is equivalent to disabling the fsync configuration parameter.
           Read the detailed documentation before using this!

       -h hostname
           Specifies the IP host name or address on which postgres is to listen for TCP/IP connections from
           client applications. The value can also be a comma-separated list of addresses, or * to specify
           listening on all available interfaces. An empty value specifies not listening on any IP addresses, in
           which case only Unix-domain sockets can be used to connect to the server. Defaults to listening only
           on localhost. Specifying this option is equivalent to setting the listen_addresses configuration
           parameter.

       -i
           Allows remote clients to connect via TCP/IP (Internet domain) connections. Without this option, only
           local connections are accepted. This option is equivalent to setting listen_addresses to * in
           postgresql.conf or via -h.

           This option is deprecated since it does not allow access to the full functionality of
           listen_addresses. It's usually better to set listen_addresses directly.

       -k directory
           Specifies the directory of the Unix-domain socket on which postgres is to listen for connections from
           client applications. The default is normally /tmp, but can be changed at build time.

       -l
           Enables secure connections using SSL.  Postgres-XC must have been compiled with support for SSL for
           this option to be available. For more information on using SSL, refer to Section 16.9, “Secure TCP/IP
           Connections with SSL”, in the documentation.

       -N max-connections
           Sets the maximum number of client connections that this server will accept. The default value of this
           parameter is chosen automatically by initdb. Specifying this option is equivalent to setting the
           max_connections configuration parameter.

       -o extra-options
           The command-line-style options specified in extra-options are passed to all server processes started
           by this postgres process. If the option string contains any spaces, the entire string must be quoted.

           The use of this option is obsolete; all command-line options for server processes can be specified
           directly on the postgres command line.

       -p port
           Specifies the TCP/IP port or local Unix domain socket file extension on which postgres is to listen
           for connections from client applications. Defaults to the value of the PGPORT environment variable,
           or if PGPORT is not set, then defaults to the value established during compilation (normally 5432).
           If you specify a port other than the default port, then all client applications must specify the same
           port using either command-line options or PGPORT.

       -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 work-mem
           Specifies the amount of memory to be used by internal sorts and hashes before resorting to temporary
           disk files. See the description of the work_mem configuration parameter in Section 17.4.1, “Memory”,
           in the documentation.

       -V, --version
           Print the postgres version and exit.

       --name=value
           Sets a named run-time parameter; a shorter form of -c.

       --describe-config
           This option dumps out the server's internal configuration variables, descriptions, and defaults in
           tab-delimited COPY format. It is designed primarily for use by administration tools.

       --coordinator

               Note
               The following description applies only to Postgres-XC
           Specifies postgres server should run as a Coordinator.

       --datanode

               Note
               The following description applies only to Postgres-XC
           Specifies postgres server should run as a Datanode.

       -?, --help
           Show help about postgres command line arguments, and exit.

   Semi-internal Options
       The options described here are used mainly for debugging purposes, and in some cases to assist with
       recovery of severely damaged databases. There should be no reason to use them in a production database
       setup. They are listed here only for use by Postgres-XC system developers. Furthermore, these options
       might change or be removed in a future release without notice.

       -f { s | i | o | b | t | n | m | h }
           Forbids the use of particular scan and join methods: s and i disable sequential and index scans
           respectively, o, b and t disable index-only scans, bitmap index scans, and TID scans respectively,
           while n, m, and h disable nested-loop, merge and hash joins respectively.

           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.

       -n
           This option is for debugging problems that cause a server process to die abnormally. The ordinary
           strategy in this situation is to notify all other server processes that they must terminate and then
           reinitialize the shared memory and semaphores. This is because an errant server process could have
           corrupted some shared state before terminating. This option specifies that postgres will not
           reinitialize shared data structures. A knowledgeable system programmer can then use a debugger to
           examine shared memory and semaphore state.

       -O
           Allows the structure of system tables to be modified. This is used by initdb.

       -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.

       -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.

       -T
           This option is for debugging problems that cause a server process to die abnormally. The ordinary
           strategy in this situation is to notify all other server processes that they must terminate and then
           reinitialize the shared memory and semaphores. This is because an errant server process could have
           corrupted some shared state before terminating. This option specifies that postgres will stop all
           other server processes by sending the signal SIGSTOP, but will not cause them to terminate. This
           permits system programmers to collect core dumps from all server processes by hand.

       -v protocol
           Specifies the version number of the frontend/backend protocol to be used for a particular session.
           This option is for internal use only.

       -W seconds
           A delay of this many seconds occurs when a new server process is started, after it conducts the
           authentication procedure. This is intended to give an opportunity to attach to the server process
           with a debugger.

       --localxid

               Note
               The following description applies only to Postgres-XC
           Use local transaction IDs rather than GXID. This option applies only to Postgres-XC. It is only used
           by initdb. Explicit use of this option may cause database inconsistency.

   Options for Single-User Mode
       The following options only apply to the single-user mode.

       --single
           Selects the single-user mode. This must be the first argument on the command line.

       database
           Specifies the name of the database to be accessed. This must be the last argument on the command
           line. If it is omitted it defaults to the user name.

       -E
           Echo all commands.

       -j
           Disables use of newline as a statement delimiter.

       -r filename
           Send all server log output to filename. In normal multiuser mode, this option is ignored, and stderr
           is used by all processes.

ENVIRONMENT

       PGCLIENTENCODING
           Default character encoding used by clients. (The clients can override this individually.) This value
           can also be set in the configuration file.

       PGDATA
           Default data directory location

       PGDATESTYLE
           Default value of the DateStyle run-time parameter. (The use of this environment variable is
           deprecated.)

       PGPORT
           Default port number (preferably set in the configuration file)

       TZ
           Server time zone

DIAGNOSTICS

       A failure message mentioning semget or shmget probably indicates you need to configure your kernel to
       provide adequate shared memory and semaphores. For more discussion see Section 16.4, “Managing Kernel
       Resources”, in the documentation. You might be able to postpone reconfiguring your kernel by decreasing
       shared_buffers to reduce the shared memory consumption of Postgres-XC, and/or by reducing max_connections
       to reduce the semaphore consumption.

       A failure message suggesting that another server is already running should be checked carefully, for
       example by using the command

           $ ps ax | grep postgres

       or

           $ ps -ef | grep postgres

       depending on your system. If you are certain that no conflicting server is running, you can remove the
       lock file mentioned in the message and try again.

       A failure message indicating inability to bind to a port might indicate that that port is already in use
       by some non-Postgres-XC process. You might also get this error if you terminate postgres and immediately
       restart it using the same port; in this case, you must simply wait a few seconds until the operating
       system closes the port before trying again. Finally, you might get this error if you specify a port
       number that your operating system considers to be reserved. For example, many versions of Unix consider
       port numbers under 1024 to be “trusted” and only permit the Unix superuser to access them.

NOTES

       The utility command pg_ctl(1) can be used to start and shut down the postgres server safely and
       comfortably.

       If at all possible, do not use SIGKILL to kill the main postgres server. Doing so will prevent postgres
       from freeing the system resources (e.g., shared memory and semaphores) that it holds before terminating.
       This might cause problems for starting a fresh postgres run.

       To terminate the postgres server normally, the signals SIGTERM, SIGINT, or SIGQUIT can be used. The first
       will wait for all clients to terminate before quitting, the second will forcefully disconnect all
       clients, and the third will quit immediately without proper shutdown, resulting in a recovery run during
       restart.

       The SIGHUP signal will reload the server configuration files. It is also possible to send SIGHUP to an
       individual server process, but that is usually not sensible.

       To cancel a running query, send the SIGINT signal to the process running that command.

       The postgres server uses SIGTERM to tell subordinate server processes 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 server processthe main postgres process will interpret this as a crash and will force
       all the sibling processes to quit as part of its standard crash-recovery procedure.

BUGS

       The -- options will not work on FreeBSD or OpenBSD. Use -c instead. This is a bug in the affected
       operating systems; a future release of Postgres-XC will provide a workaround if this is not fixed.

USAGE

       To start a single-user mode server, use a command like

           postgres --single -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 single-user mode 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 backslash just before each newline except the last one.

       But if you use the -j command line switch, then newline does not terminate 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 -j, two consecutive EOFs are needed to
       exit.

       Note that the single-user mode server does not provide sophisticated line-editing features (no command
       history, for example). Single-User mode also does not do any background processing, like automatic
       checkpoints.

EXAMPLES

       To start postgres in the background using default values, type:

           $ nohup postgres >logfile 2>&1 </dev/null &

       To start postgres with as a Coordinator a specific port, e.g. 1234:

           $ postgres --coordinator -p 1234

       To connect to this server using psql, specify this port with the -p option:

           $ psql -p 1234

       or set the environment variable PGPORT:

           $ export PGPORT=1234
           $ psql

       Named run-time parameters can be set in either of these styles:

           $ postgres --coordinator -c work_mem=1234
           $ postgres --coordinator --work-mem=1234

       Either form overrides whatever setting might exist for work_mem in postgresql.conf. Notice that
       underscores in parameter names can be written as either underscore or dash on the command line. Except
       for short-term experiments, it's probably better practice to edit the setting in postgresql.conf than to
       rely on a command-line switch to set a parameter.

SEE ALSO

       initdb(1), pg_ctl(1)