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| <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>postgres</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="pgwaldump.html" title="pg_waldump" /><link rel="next" href="internals.html" title="Part VII. Internals" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center"><span class="application">postgres</span></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="pgwaldump.html" title="pg_waldump">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="reference-server.html" title="PostgreSQL Server Applications">Up</a></td><th width="60%" align="center">PostgreSQL Server Applications</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="internals.html" title="Part VII. Internals">Next</a></td></tr></table><hr /></div><div class="refentry" id="APP-POSTGRES"><div class="titlepage"></div><a id="id-1.9.5.14.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle"><span class="application">postgres</span></span></h2><p>postgres — <span class="productname">PostgreSQL</span> database server</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="cmdsynopsis"><p id="id-1.9.5.14.4.1"><code class="command">postgres</code> [<em class="replaceable"><code>option</code></em>...]</p></div></div><div class="refsect1" id="id-1.9.5.14.5"><h2>Description</h2><p> |
| <code class="command">postgres</code> is the |
| <span class="productname">PostgreSQL</span> database server. In order |
| for a client application to access a database it connects (over a |
| network or locally) to a running <code class="command">postgres</code> instance. |
| The <code class="command">postgres</code> instance then starts a separate server |
| process to handle the connection. |
| </p><p> |
| One <code class="command">postgres</code> 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 |
| <span class="quote">“<span class="quote">data area</span>”</span>). More than one |
| <code class="command">postgres</code> instance can run on a system at one |
| time, so long as they use different data areas and different |
| communication ports (see below). When |
| <code class="command">postgres</code> starts it needs to know the location |
| of the data area. The location must be specified by the |
| <code class="option">-D</code> option or the <code class="envar">PGDATA</code> environment |
| variable; there is no default. Typically, <code class="option">-D</code> or |
| <code class="envar">PGDATA</code> points directly to the data area directory |
| created by <a class="xref" href="app-initdb.html" title="initdb"><span class="refentrytitle"><span class="application">initdb</span></span></a>. Other possible file layouts are |
| discussed in <a class="xref" href="runtime-config-file-locations.html" title="20.2. File Locations">Section 20.2</a>. |
| </p><p> |
| By default <code class="command">postgres</code> starts in the |
| foreground and prints log messages to the standard error stream. In |
| practical applications <code class="command">postgres</code> |
| should be started as a background process, perhaps at boot time. |
| </p><p> |
| The <code class="command">postgres</code> command can also be called in |
| single-user mode. The primary use for this mode is during |
| bootstrapping by <a class="xref" href="app-initdb.html" title="initdb"><span class="refentrytitle"><span class="application">initdb</span></span></a>. 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. |
| </p></div><div class="refsect1" id="APP-POSTGRES-OPTIONS"><h2>Options</h2><p> |
| <code class="command">postgres</code> accepts the following command-line |
| arguments. For a detailed discussion of the options consult <a class="xref" href="runtime-config.html" title="Chapter 20. Server Configuration">Chapter 20</a>. 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 <code class="envar">PGOPTIONS</code> is |
| set, then <span class="application">libpq</span>-based clients will pass that |
| string to the server, which will interpret it as |
| <code class="command">postgres</code> command-line options. |
| </p><div class="refsect2" id="id-1.9.5.14.6.3"><h3>General Purpose</h3><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="option">-B <em class="replaceable"><code>nbuffers</code></em></code></span></dt><dd><p> |
| Sets the number of shared buffers for use by the server |
| processes. The default value of this parameter is chosen |
| automatically by <span class="application">initdb</span>. |
| Specifying this option is equivalent to setting the |
| <a class="xref" href="runtime-config-resource.html#GUC-SHARED-BUFFERS">shared_buffers</a> configuration parameter. |
| </p></dd><dt><span class="term"><code class="option">-c <em class="replaceable"><code>name</code></em>=<em class="replaceable"><code>value</code></em></code></span></dt><dd><p> |
| Sets a named run-time parameter. The configuration parameters |
| supported by <span class="productname">PostgreSQL</span> are |
| described in <a class="xref" href="runtime-config.html" title="Chapter 20. Server Configuration">Chapter 20</a>. Most of the |
| other command line options are in fact short forms of such a |
| parameter assignment. <code class="option">-c</code> can appear multiple times |
| to set multiple parameters. |
| </p></dd><dt><span class="term"><code class="option">-C <em class="replaceable"><code>name</code></em></code></span></dt><dd><p> |
| Prints the value of the named run-time parameter, and exits. |
| (See the <code class="option">-c</code> option above for details.) This |
| returns values from |
| <code class="filename">postgresql.conf</code>, modified by any parameters |
| supplied in this invocation. It does not reflect parameters |
| supplied when the cluster was started. |
| </p><p> |
| This can be used on a running server for most parameters. However, |
| the server must be shut down for some runtime-computed parameters |
| (e.g., <a class="xref" href="runtime-config-preset.html#GUC-SHARED-MEMORY-SIZE">shared_memory_size</a>, |
| <a class="xref" href="runtime-config-preset.html#GUC-SHARED-MEMORY-SIZE-IN-HUGE-PAGES">shared_memory_size_in_huge_pages</a>, and |
| <a class="xref" href="runtime-config-preset.html#GUC-WAL-SEGMENT-SIZE">wal_segment_size</a>). |
| </p><p> |
| This option is meant for other programs that interact with a server |
| instance, such as <a class="xref" href="app-pg-ctl.html" title="pg_ctl"><span class="refentrytitle"><span class="application">pg_ctl</span></span></a>, to query configuration |
| parameter values. User-facing applications should instead use <a class="link" href="sql-show.html" title="SHOW"><code class="command">SHOW</code></a> or the <code class="structname">pg_settings</code> view. |
| </p></dd><dt><span class="term"><code class="option">-d <em class="replaceable"><code>debug-level</code></em></code></span></dt><dd><p> |
| 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 <code class="literal">-d |
| 0</code> for a specific session, which will prevent the |
| server log level of the parent <code class="command">postgres</code> process from being |
| propagated to this session. |
| </p></dd><dt><span class="term"><code class="option">-D <em class="replaceable"><code>datadir</code></em></code></span></dt><dd><p> |
| Specifies the file system location of the database |
| configuration files. See |
| <a class="xref" href="runtime-config-file-locations.html" title="20.2. File Locations">Section 20.2</a> for details. |
| </p></dd><dt><span class="term"><code class="option">-e</code></span></dt><dd><p> |
| Sets the default date style to <span class="quote">“<span class="quote">European</span>”</span>, that is |
| <code class="literal">DMY</code> ordering of input date fields. This also causes |
| the day to be printed before the month in certain date output formats. |
| See <a class="xref" href="datatype-datetime.html" title="8.5. Date/Time Types">Section 8.5</a> for more information. |
| </p></dd><dt><span class="term"><code class="option">-F</code></span></dt><dd><p> |
| Disables <code class="function">fsync</code> 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 <a class="xref" href="runtime-config-wal.html#GUC-FSYNC">fsync</a> configuration |
| parameter. Read the detailed documentation before using this! |
| </p></dd><dt><span class="term"><code class="option">-h <em class="replaceable"><code>hostname</code></em></code></span></dt><dd><p> |
| Specifies the IP host name or address on which |
| <code class="command">postgres</code> is to listen for TCP/IP |
| connections from client applications. The value can also be a |
| comma-separated list of addresses, or <code class="literal">*</code> 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 |
| <span class="systemitem">localhost</span>. |
| Specifying this option is equivalent to setting the <a class="xref" href="runtime-config-connection.html#GUC-LISTEN-ADDRESSES">listen_addresses</a> configuration parameter. |
| </p></dd><dt><span class="term"><code class="option">-i</code></span></dt><dd><p> |
| 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 |
| <code class="varname">listen_addresses</code> to <code class="literal">*</code> in |
| <code class="filename">postgresql.conf</code> or via <code class="option">-h</code>. |
| </p><p> |
| This option is deprecated since it does not allow access to the |
| full functionality of <a class="xref" href="runtime-config-connection.html#GUC-LISTEN-ADDRESSES">listen_addresses</a>. |
| It's usually better to set <code class="varname">listen_addresses</code> directly. |
| </p></dd><dt><span class="term"><code class="option">-k <em class="replaceable"><code>directory</code></em></code></span></dt><dd><p> |
| Specifies the directory of the Unix-domain socket on which |
| <code class="command">postgres</code> is to listen for |
| connections from client applications. The value can also be a |
| comma-separated list of directories. An empty value |
| specifies not listening on any Unix-domain sockets, in which case |
| only TCP/IP sockets can be used to connect to the server. |
| The default value is normally |
| <code class="filename">/tmp</code>, but that can be changed at build time. |
| Specifying this option is equivalent to setting the <a class="xref" href="runtime-config-connection.html#GUC-UNIX-SOCKET-DIRECTORIES">unix_socket_directories</a> configuration parameter. |
| </p></dd><dt><span class="term"><code class="option">-l</code></span></dt><dd><p> |
| Enables secure connections using <acronym class="acronym">SSL</acronym>. |
| <span class="productname">PostgreSQL</span> must have been compiled with |
| support for <acronym class="acronym">SSL</acronym> for this option to be |
| available. For more information on using <acronym class="acronym">SSL</acronym>, |
| refer to <a class="xref" href="ssl-tcp.html" title="19.9. Secure TCP/IP Connections with SSL">Section 19.9</a>. |
| </p></dd><dt><span class="term"><code class="option">-N <em class="replaceable"><code>max-connections</code></em></code></span></dt><dd><p> |
| Sets the maximum number of client connections that this |
| server will accept. The default value of this parameter is chosen |
| automatically by <span class="application">initdb</span>. |
| Specifying this option is equivalent to setting the |
| <a class="xref" href="runtime-config-connection.html#GUC-MAX-CONNECTIONS">max_connections</a> configuration parameter. |
| </p></dd><dt><span class="term"><code class="option">-p <em class="replaceable"><code>port</code></em></code></span></dt><dd><p> |
| Specifies the TCP/IP port or local Unix domain socket file |
| extension on which <code class="command">postgres</code> |
| is to listen for connections from client applications. |
| Defaults to the value of the <code class="envar">PGPORT</code> environment |
| variable, or if <code class="envar">PGPORT</code> 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 <code class="envar">PGPORT</code>. |
| </p></dd><dt><span class="term"><code class="option">-s</code></span></dt><dd><p> |
| 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. |
| </p></dd><dt><span class="term"><code class="option">-S</code> <em class="replaceable"><code>work-mem</code></em></span></dt><dd><p> |
| Specifies the base amount of memory to be used by sorts and |
| hash tables before resorting to temporary disk files. See the |
| description of the <code class="varname">work_mem</code> configuration |
| parameter in <a class="xref" href="runtime-config-resource.html#RUNTIME-CONFIG-RESOURCE-MEMORY" title="20.4.1. Memory">Section 20.4.1</a>. |
| </p></dd><dt><span class="term"><code class="option">-V</code><br /></span><span class="term"><code class="option">--version</code></span></dt><dd><p> |
| Print the <span class="application">postgres</span> version and exit. |
| </p></dd><dt><span class="term"><code class="option">--<em class="replaceable"><code>name</code></em>=<em class="replaceable"><code>value</code></em></code></span></dt><dd><p> |
| Sets a named run-time parameter; a shorter form of |
| <code class="option">-c</code>. |
| </p></dd><dt><span class="term"><code class="option">--describe-config</code></span></dt><dd><p> |
| This option dumps out the server's internal configuration variables, |
| descriptions, and defaults in tab-delimited <code class="command">COPY</code> format. |
| It is designed primarily for use by administration tools. |
| </p></dd><dt><span class="term"><code class="option">-?</code><br /></span><span class="term"><code class="option">--help</code></span></dt><dd><p> |
| Show help about <span class="application">postgres</span> command line |
| arguments, and exit. |
| </p></dd></dl></div></div><div class="refsect2" id="id-1.9.5.14.6.4"><h3>Semi-Internal Options</h3><p> |
| 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 <span class="productname">PostgreSQL</span> |
| system developers. Furthermore, these options might |
| change or be removed in a future release without notice. |
| </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="option">-f</code> <code class="literal">{ s | i | o | b | t | n | m | h }</code></span></dt><dd><p> |
| Forbids the use of particular scan and join methods: |
| <code class="literal">s</code> and <code class="literal">i</code> |
| disable sequential and index scans respectively, |
| <code class="literal">o</code>, <code class="literal">b</code> and <code class="literal">t</code> |
| disable index-only scans, bitmap index scans, and TID scans |
| respectively, while |
| <code class="literal">n</code>, <code class="literal">m</code>, and <code class="literal">h</code> |
| disable nested-loop, merge and hash joins respectively. |
| </p><p> |
| Neither sequential scans nor nested-loop joins can be disabled |
| completely; the <code class="literal">-fs</code> and |
| <code class="literal">-fn</code> options simply discourage the optimizer |
| from using those plan types if it has any other alternative. |
| </p></dd><dt><span class="term"><code class="option">-O</code></span></dt><dd><p> |
| Allows the structure of system tables to be modified. This is |
| used by <code class="command">initdb</code>. |
| </p></dd><dt><span class="term"><code class="option">-P</code></span></dt><dd><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. |
| </p></dd><dt><span class="term"><code class="option">-t</code> <code class="literal">pa[rser] | pl[anner] | e[xecutor]</code></span></dt><dd><p> |
| Print timing statistics for each query relating to each of the |
| major system modules. This option cannot be used together |
| with the <code class="option">-s</code> option. |
| </p></dd><dt><span class="term"><code class="option">-T</code></span></dt><dd><p> |
| 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, by sending them <span class="systemitem">SIGQUIT</span> |
| signals. With this option, <span class="systemitem">SIGABRT</span> |
| will be sent instead, resulting in production of core dump files. |
| </p></dd><dt><span class="term"><code class="option">-v</code> <em class="replaceable"><code>protocol</code></em></span></dt><dd><p> |
| Specifies the version number of the frontend/backend protocol |
| to be used for a particular session. This option is for |
| internal use only. |
| </p></dd><dt><span class="term"><code class="option">-W</code> <em class="replaceable"><code>seconds</code></em></span></dt><dd><p> |
| 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. |
| </p></dd></dl></div></div><div class="refsect2" id="id-1.9.5.14.6.5"><h3>Options for Single-User Mode</h3><a id="id-1.9.5.14.6.5.2" class="indexterm"></a><p> |
| The following options only apply to the single-user mode |
| (see <a class="xref" href="app-postgres.html#APP-POSTGRES-SINGLE-USER" title="Single-User Mode">Single-User Mode</a> below). |
| </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="option">--single</code></span></dt><dd><p> |
| Selects the single-user mode. This must be the first argument |
| on the command line. |
| </p></dd><dt><span class="term"><em class="replaceable"><code>database</code></em></span></dt><dd><p> |
| 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. |
| </p></dd><dt><span class="term"><code class="option">-E</code></span></dt><dd><p> |
| Echo all commands to standard output before executing them. |
| </p></dd><dt><span class="term"><code class="option">-j</code></span></dt><dd><p> |
| Use semicolon followed by two newlines, rather than just newline, |
| as the command entry terminator. |
| </p></dd><dt><span class="term"><code class="option">-r</code> <em class="replaceable"><code>filename</code></em></span></dt><dd><p> |
| Send all server log output to <em class="replaceable"><code>filename</code></em>. This option is only |
| honored when supplied as a command-line option. |
| </p></dd></dl></div></div></div><div class="refsect1" id="id-1.9.5.14.7"><h2>Environment</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="envar">PGCLIENTENCODING</code></span></dt><dd><p> |
| Default character encoding used by clients. (The clients can |
| override this individually.) This value can also be set in the |
| configuration file. |
| </p></dd><dt><span class="term"><code class="envar">PGDATA</code></span></dt><dd><p> |
| Default data directory location |
| </p></dd><dt><span class="term"><code class="envar">PGDATESTYLE</code></span></dt><dd><p> |
| Default value of the <a class="xref" href="runtime-config-client.html#GUC-DATESTYLE">DateStyle</a> run-time |
| parameter. (The use of this environment variable is deprecated.) |
| </p></dd><dt><span class="term"><code class="envar">PGPORT</code></span></dt><dd><p> |
| Default port number (preferably set in the configuration file) |
| </p></dd></dl></div></div><div class="refsect1" id="id-1.9.5.14.8"><h2>Diagnostics</h2><p> |
| A failure message mentioning <code class="literal">semget</code> or |
| <code class="literal">shmget</code> probably indicates you need to configure your |
| kernel to provide adequate shared memory and semaphores. For more |
| discussion see <a class="xref" href="kernel-resources.html" title="19.4. Managing Kernel Resources">Section 19.4</a>. You might be able |
| to postpone reconfiguring your kernel by decreasing <a class="xref" href="runtime-config-resource.html#GUC-SHARED-BUFFERS">shared_buffers</a> to reduce the shared memory |
| consumption of <span class="productname">PostgreSQL</span>, and/or by reducing |
| <a class="xref" href="runtime-config-connection.html#GUC-MAX-CONNECTIONS">max_connections</a> to reduce the semaphore |
| consumption. |
| </p><p> |
| A failure message suggesting that another server is already running |
| should be checked carefully, for example by using the command |
| </p><pre class="screen"> |
| <code class="prompt">$</code> <strong class="userinput"><code>ps ax | grep postgres</code></strong> |
| </pre><p> |
| or |
| </p><pre class="screen"> |
| <code class="prompt">$</code> <strong class="userinput"><code>ps -ef | grep postgres</code></strong> |
| </pre><p> |
| 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. |
| </p><p> |
| A failure message indicating inability to bind to a port might |
| indicate that that port is already in use by some |
| non-<span class="productname">PostgreSQL</span> process. You might also |
| get this error if you terminate <code class="command">postgres</code> |
| 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 <span class="quote">“<span class="quote">trusted</span>”</span> and only permit |
| the Unix superuser to access them. |
| </p></div><div class="refsect1" id="id-1.9.5.14.9"><h2>Notes</h2><p> |
| The utility command <a class="xref" href="app-pg-ctl.html" title="pg_ctl"><span class="refentrytitle"><span class="application">pg_ctl</span></span></a> can be used to |
| start and shut down the <code class="command">postgres</code> server |
| safely and comfortably. |
| </p><p> |
| If at all possible, <span class="emphasis"><em>do not</em></span> use |
| <code class="literal">SIGKILL</code> to kill the main |
| <code class="command">postgres</code> server. Doing so will prevent |
| <code class="command">postgres</code> from freeing the system |
| resources (e.g., shared memory and semaphores) that it holds before |
| terminating. This might cause problems for starting a fresh |
| <code class="command">postgres</code> run. |
| </p><p> |
| To terminate the <code class="command">postgres</code> server normally, the |
| signals <code class="literal">SIGTERM</code>, <code class="literal">SIGINT</code>, or |
| <code class="literal">SIGQUIT</code> 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. |
| </p><p> |
| The <code class="literal">SIGHUP</code> signal will reload |
| the server configuration files. It is also possible to send |
| <code class="literal">SIGHUP</code> to an individual server process, but that |
| is usually not sensible. |
| </p><p> |
| To cancel a running query, send the <code class="literal">SIGINT</code> signal |
| to the process running that command. To terminate a backend process |
| cleanly, send <code class="literal">SIGTERM</code> to that process. See |
| also <code class="function">pg_cancel_backend</code> and <code class="function">pg_terminate_backend</code> |
| in <a class="xref" href="functions-admin.html#FUNCTIONS-ADMIN-SIGNAL" title="9.27.2. Server Signaling Functions">Section 9.27.2</a> for the SQL-callable equivalents |
| of these two actions. |
| </p><p> |
| The <code class="command">postgres</code> server uses <code class="literal">SIGQUIT</code> |
| to tell subordinate server processes to terminate without normal |
| cleanup. |
| This signal <span class="emphasis"><em>should not</em></span> be used by users. It |
| is also unwise to send <code class="literal">SIGKILL</code> to a server |
| process — the main <code class="command">postgres</code> process will |
| interpret this as a crash and will force all the sibling processes |
| to quit as part of its standard crash-recovery procedure. |
| </p></div><div class="refsect1" id="APP-POSTGRES-BUGS"><h2>Bugs</h2><p> |
| The <code class="option">--</code> options will not work on <span class="systemitem">FreeBSD</span> or <span class="systemitem">OpenBSD</span>. |
| Use <code class="option">-c</code> instead. This is a bug in the affected operating |
| systems; a future release of <span class="productname">PostgreSQL</span> |
| will provide a workaround if this is not fixed. |
| </p></div><div class="refsect1" id="APP-POSTGRES-SINGLE-USER"><h2>Single-User Mode</h2><p> |
| To start a single-user mode server, use a command like |
| </p><pre class="screen"> |
| <strong class="userinput"><code>postgres --single -D /usr/local/pgsql/data <em class="replaceable"><code>other-options</code></em> my_database</code></strong> |
| </pre><p> |
| Provide the correct path to the database directory with <code class="option">-D</code>, or |
| make sure that the environment variable <code class="envar">PGDATA</code> is set. |
| Also specify the name of the particular database you want to work in. |
| </p><p> |
| Normally, the single-user mode server treats newline as the command |
| entry terminator; there is no intelligence about semicolons, |
| as there is in <span class="application">psql</span>. To continue a command |
| across multiple lines, you must type backslash just before each |
| newline except the last one. The backslash and adjacent newline are |
| both dropped from the input command. Note that this will happen even |
| when within a string literal or comment. |
| </p><p> |
| But if you use the <code class="option">-j</code> command line switch, a single newline |
| does not terminate command entry; instead, the sequence |
| semicolon-newline-newline does. That is, type a semicolon immediately |
| followed by a completely empty line. Backslash-newline is not |
| treated specially in this mode. Again, there is no intelligence about |
| such a sequence appearing within a string literal or comment. |
| </p><p> |
| In either input mode, if you type a semicolon that is not just before or |
| part of a command entry terminator, it is considered a command separator. |
| When you do type a command entry terminator, the multiple statements |
| you've entered will be executed as a single transaction. |
| </p><p> |
| To quit the session, type <acronym class="acronym">EOF</acronym> |
| (<span class="keycap"><strong>Control</strong></span>+<span class="keycap"><strong>D</strong></span>, usually). |
| If you've entered any text since the last command entry terminator, |
| then <acronym class="acronym">EOF</acronym> will be taken as a command entry terminator, |
| and another <acronym class="acronym">EOF</acronym> will be needed to exit. |
| </p><p> |
| 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, such as |
| automatic checkpoints or replication. |
| </p></div><div class="refsect1" id="APP-POSTGRES-EXAMPLES"><h2>Examples</h2><p> |
| To start <code class="command">postgres</code> in the background |
| using default values, type: |
|
|
| </p><pre class="screen"> |
| <code class="prompt">$</code> <strong class="userinput"><code>nohup postgres >logfile 2>&1 </dev/null &</code></strong> |
| </pre><p> |
| </p><p> |
| To start <code class="command">postgres</code> with a specific |
| port, e.g., 1234: |
| </p><pre class="screen"> |
| <code class="prompt">$</code> <strong class="userinput"><code>postgres -p 1234</code></strong> |
| </pre><p> |
| To connect to this server using <span class="application">psql</span>, specify this port with the -p option: |
| </p><pre class="screen"> |
| <code class="prompt">$</code> <strong class="userinput"><code>psql -p 1234</code></strong> |
| </pre><p> |
| or set the environment variable <code class="envar">PGPORT</code>: |
| </p><pre class="screen"> |
| <code class="prompt">$</code> <strong class="userinput"><code>export PGPORT=1234</code></strong> |
| <code class="prompt">$</code> <strong class="userinput"><code>psql</code></strong> |
| </pre><p> |
| </p><p> |
| Named run-time parameters can be set in either of these styles: |
| </p><pre class="screen"> |
| <code class="prompt">$</code> <strong class="userinput"><code>postgres -c work_mem=1234</code></strong> |
| <code class="prompt">$</code> <strong class="userinput"><code>postgres --work-mem=1234</code></strong> |
| </pre><p> |
| Either form overrides whatever setting might exist for |
| <code class="varname">work_mem</code> in <code class="filename">postgresql.conf</code>. 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 |
| <code class="filename">postgresql.conf</code> than to rely on a command-line switch |
| to set a parameter. |
| </p></div><div class="refsect1" id="id-1.9.5.14.13"><h2>See Also</h2><p> |
| <a class="xref" href="app-initdb.html" title="initdb"><span class="refentrytitle"><span class="application">initdb</span></span></a>, |
| <a class="xref" href="app-pg-ctl.html" title="pg_ctl"><span class="refentrytitle"><span class="application">pg_ctl</span></span></a> |
| </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="pgwaldump.html" title="pg_waldump">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="reference-server.html" title="PostgreSQL Server Applications">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="internals.html" title="Part VII. Internals">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="application">pg_waldump</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> Part VII. Internals</td></tr></table></div></body></html> |
