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diff --git a/doc/src/sgml/ref/postgres-ref.sgml b/doc/src/sgml/ref/postgres-ref.sgml new file mode 100644 index 0000000..4aaa7ab --- /dev/null +++ b/doc/src/sgml/ref/postgres-ref.sgml @@ -0,0 +1,837 @@ +<!-- +doc/src/sgml/ref/postgres-ref.sgml +PostgreSQL documentation +--> + +<refentry id="app-postgres"> + <indexterm zone="app-postgres"> + <primary>postgres</primary> + </indexterm> + + <refmeta> + <refentrytitle><application>postgres</application></refentrytitle> + <manvolnum>1</manvolnum> + <refmiscinfo>Application</refmiscinfo> + </refmeta> + + <refnamediv> + <refname>postgres</refname> + <refpurpose><productname>PostgreSQL</productname> database server</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <cmdsynopsis> + <command>postgres</command> + <arg rep="repeat"><replaceable>option</replaceable></arg> + </cmdsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para> + <command>postgres</command> is the + <productname>PostgreSQL</productname> database server. In order + for a client application to access a database it connects (over a + network or locally) to a running <command>postgres</command> instance. + The <command>postgres</command> instance then starts a separate server + process to handle the connection. + </para> + + <para> + One <command>postgres</command> 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 + <quote>data area</quote>). More than one + <command>postgres</command> instance can run on a system at one + time, so long as they use different data areas and different + communication ports (see below). When + <command>postgres</command> starts it needs to know the location + of the data area. The location must be specified by the + <option>-D</option> option or the <envar>PGDATA</envar> environment + variable; there is no default. Typically, <option>-D</option> or + <envar>PGDATA</envar> points directly to the data area directory + created by <xref linkend="app-initdb"/>. Other possible file layouts are + discussed in <xref linkend="runtime-config-file-locations"/>. + </para> + + <para> + By default <command>postgres</command> starts in the + foreground and prints log messages to the standard error stream. In + practical applications <command>postgres</command> + should be started as a background process, perhaps at boot time. + </para> + + <para> + The <command>postgres</command> command can also be called in + single-user mode. The primary use for this mode is during + bootstrapping by <xref linkend="app-initdb"/>. 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. + </para> + </refsect1> + + <refsect1 id="app-postgres-options"> + <title>Options</title> + + <para> + <command>postgres</command> accepts the following command-line + arguments. For a detailed discussion of the options consult <xref + linkend="runtime-config"/>. 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 <envar>PGOPTIONS</envar> is + set, then <application>libpq</application>-based clients will pass that + string to the server, which will interpret it as + <command>postgres</command> command-line options. + </para> + + <refsect2> + <title>General Purpose</title> + + <variablelist> + <varlistentry> + <term><option>-B <replaceable class="parameter">nbuffers</replaceable></option></term> + <listitem> + <para> + Sets the number of shared buffers for use by the server + processes. The default value of this parameter is chosen + automatically by <application>initdb</application>. + Specifying this option is equivalent to setting the + <xref linkend="guc-shared-buffers"/> configuration parameter. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-c <replaceable>name</replaceable>=<replaceable>value</replaceable></option></term> + <listitem> + <para> + Sets a named run-time parameter. The configuration parameters + supported by <productname>PostgreSQL</productname> are + described in <xref linkend="runtime-config"/>. Most of the + other command line options are in fact short forms of such a + parameter assignment. <option>-c</option> can appear multiple times + to set multiple parameters. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-C <replaceable>name</replaceable></option></term> + <listitem> + <para> + Prints the value of the named run-time parameter, and exits. + (See the <option>-c</option> option above for details.) This can + be used on a running server, and returns values from + <filename>postgresql.conf</filename>, modified by any parameters + supplied in this invocation. It does not reflect parameters + supplied when the cluster was started. + </para> + + <para> + This option is meant for other programs that interact with a server + instance, such as <xref linkend="app-pg-ctl"/>, to query configuration + parameter values. User-facing applications should instead use <link + linkend="sql-show"><command>SHOW</command></link> or the <structname>pg_settings</structname> view. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-d <replaceable>debug-level</replaceable></option></term> + <listitem> + <para> + 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 <literal>-d + 0</literal> for a specific session, which will prevent the + server log level of the parent <command>postgres</command> process from being + propagated to this session. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-D <replaceable class="parameter">datadir</replaceable></option></term> + <listitem> + <para> + Specifies the file system location of the database + configuration files. See + <xref linkend="runtime-config-file-locations"/> for details. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-e</option></term> + <listitem> + <para> + Sets the default date style to <quote>European</quote>, that is + <literal>DMY</literal> ordering of input date fields. This also causes + the day to be printed before the month in certain date output formats. + See <xref linkend="datatype-datetime"/> for more information. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-F</option></term> + <listitem> + <para> + Disables <function>fsync</function> 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 <xref linkend="guc-fsync"/> configuration + parameter. Read the detailed documentation before using this! + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-h <replaceable class="parameter">hostname</replaceable></option></term> + <listitem> + <para> + Specifies the IP host name or address on which + <command>postgres</command> is to listen for TCP/IP + connections from client applications. The value can also be a + comma-separated list of addresses, or <literal>*</literal> 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 + <systemitem class="systemname">localhost</systemitem>. + Specifying this option is equivalent to setting the <xref + linkend="guc-listen-addresses"/> configuration parameter. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-i</option></term> + <listitem> + <para> + 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 + <varname>listen_addresses</varname> to <literal>*</literal> in + <filename>postgresql.conf</filename> or via <option>-h</option>. + </para> + <para> + This option is deprecated since it does not allow access to the + full functionality of <xref linkend="guc-listen-addresses"/>. + It's usually better to set <varname>listen_addresses</varname> directly. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-k <replaceable class="parameter">directory</replaceable></option></term> + <listitem> + <para> + Specifies the directory of the Unix-domain socket on which + <command>postgres</command> 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 + <filename>/tmp</filename>, but that can be changed at build time. + Specifying this option is equivalent to setting the <xref + linkend="guc-unix-socket-directories"/> configuration parameter. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-l</option></term> + <listitem> + <para> + Enables secure connections using <acronym>SSL</acronym>. + <productname>PostgreSQL</productname> must have been compiled with + support for <acronym>SSL</acronym> for this option to be + available. For more information on using <acronym>SSL</acronym>, + refer to <xref linkend="ssl-tcp"/>. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-N <replaceable class="parameter">max-connections</replaceable></option></term> + <listitem> + <para> + Sets the maximum number of client connections that this + server will accept. The default value of this parameter is chosen + automatically by <application>initdb</application>. + Specifying this option is equivalent to setting the + <xref linkend="guc-max-connections"/> configuration parameter. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-p <replaceable class="parameter">port</replaceable></option></term> + <listitem> + <para> + Specifies the TCP/IP port or local Unix domain socket file + extension on which <command>postgres</command> + is to listen for connections from client applications. + Defaults to the value of the <envar>PGPORT</envar> environment + variable, or if <envar>PGPORT</envar> 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 <envar>PGPORT</envar>. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-s</option></term> + <listitem> + <para> + 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. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-S</option> <replaceable class="parameter">work-mem</replaceable></term> + <listitem> + <para> + 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 <varname>work_mem</varname> configuration + parameter in <xref linkend="runtime-config-resource-memory"/>. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-V</option></term> + <term><option>--version</option></term> + <listitem> + <para> + Print the <application>postgres</application> version and exit. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>--<replaceable>name</replaceable>=<replaceable>value</replaceable></option></term> + <listitem> + <para> + Sets a named run-time parameter; a shorter form of + <option>-c</option>. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>--describe-config</option></term> + <listitem> + <para> + This option dumps out the server's internal configuration variables, + descriptions, and defaults in tab-delimited <command>COPY</command> format. + It is designed primarily for use by administration tools. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-?</option></term> + <term><option>--help</option></term> + <listitem> + <para> + Show help about <application>postgres</application> command line + arguments, and exit. + </para> + </listitem> + </varlistentry> + </variablelist> + </refsect2> + + <refsect2> + <title>Semi-Internal Options</title> + + <para> + 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 <productname>PostgreSQL</productname> + system developers. Furthermore, these options might + change or be removed in a future release without notice. + </para> + + <variablelist> + <varlistentry> + <term><option>-f</option> <literal>{ s | i | o | b | t | n | m | h }</literal></term> + <listitem> + <para> + Forbids the use of particular scan and join methods: + <literal>s</literal> and <literal>i</literal> + disable sequential and index scans respectively, + <literal>o</literal>, <literal>b</literal> and <literal>t</literal> + disable index-only scans, bitmap index scans, and TID scans + respectively, while + <literal>n</literal>, <literal>m</literal>, and <literal>h</literal> + disable nested-loop, merge and hash joins respectively. + </para> + + <para> + Neither sequential scans nor nested-loop joins can be disabled + completely; the <literal>-fs</literal> and + <literal>-fn</literal> options simply discourage the optimizer + from using those plan types if it has any other alternative. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-n</option></term> + <listitem> + <para> + 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 <command>postgres</command> will + not reinitialize shared data structures. A knowledgeable + system programmer can then use a debugger to examine shared + memory and semaphore state. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-O</option></term> + <listitem> + <para> + Allows the structure of system tables to be modified. This is + used by <command>initdb</command>. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-P</option></term> + <listitem> + <para> + 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. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-t</option> <literal>pa[rser] | pl[anner] | e[xecutor]</literal></term> + <listitem> + <para> + Print timing statistics for each query relating to each of the + major system modules. This option cannot be used together + with the <option>-s</option> option. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-T</option></term> + <listitem> + <para> + 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 <command>postgres</command> will + stop all other server processes by sending the signal + <literal>SIGSTOP</literal>, but will not cause them to + terminate. This permits system programmers to collect core + dumps from all server processes by hand. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-v</option> <replaceable class="parameter">protocol</replaceable></term> + <listitem> + <para> + Specifies the version number of the frontend/backend protocol + to be used for a particular session. This option is for + internal use only. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-W</option> <replaceable class="parameter">seconds</replaceable></term> + <listitem> + <para> + 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. + </para> + </listitem> + </varlistentry> + </variablelist> + </refsect2> + + <refsect2> + <title>Options for Single-User Mode</title> + + <indexterm> + <primary>single-user mode</primary> + </indexterm> + + <para> + The following options only apply to the single-user mode + (see <xref linkend="app-postgres-single-user"/> below). + </para> + + <variablelist> + <varlistentry> + <term><option>--single</option></term> + <listitem> + <para> + Selects the single-user mode. This must be the first argument + on the command line. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><replaceable class="parameter">database</replaceable></term> + <listitem> + <para> + 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. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-E</option></term> + <listitem> + <para> + Echo all commands to standard output before executing them. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-j</option></term> + <listitem> + <para> + Use semicolon followed by two newlines, rather than just newline, + as the command entry terminator. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-r</option> <replaceable class="parameter">filename</replaceable></term> + <listitem> + <para> + Send all server log output to <replaceable + class="parameter">filename</replaceable>. This option is only + honored when supplied as a command-line option. + </para> + </listitem> + </varlistentry> + </variablelist> + </refsect2> + </refsect1> + + <refsect1> + <title>Environment</title> + + <variablelist> + <varlistentry> + <term><envar>PGCLIENTENCODING</envar></term> + + <listitem> + <para> + Default character encoding used by clients. (The clients can + override this individually.) This value can also be set in the + configuration file. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><envar>PGDATA</envar></term> + + <listitem> + <para> + Default data directory location + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><envar>PGDATESTYLE</envar></term> + + <listitem> + <para> + Default value of the <xref linkend="guc-datestyle"/> run-time + parameter. (The use of this environment variable is deprecated.) + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><envar>PGPORT</envar></term> + + <listitem> + <para> + Default port number (preferably set in the configuration file) + </para> + </listitem> + </varlistentry> + + </variablelist> + </refsect1> + + <refsect1> + <title>Diagnostics</title> + + <para> + A failure message mentioning <literal>semget</literal> or + <literal>shmget</literal> probably indicates you need to configure your + kernel to provide adequate shared memory and semaphores. For more + discussion see <xref linkend="kernel-resources"/>. You might be able + to postpone reconfiguring your kernel by decreasing <xref + linkend="guc-shared-buffers"/> to reduce the shared memory + consumption of <productname>PostgreSQL</productname>, and/or by reducing + <xref linkend="guc-max-connections"/> to reduce the semaphore + consumption. + </para> + + <para> + A failure message suggesting that another server is already running + should be checked carefully, for example by using the command +<screen> +<prompt>$</prompt> <userinput>ps ax | grep postgres</userinput> +</screen> + or +<screen> +<prompt>$</prompt> <userinput>ps -ef | grep postgres</userinput> +</screen> + 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. + </para> + + <para> + A failure message indicating inability to bind to a port might + indicate that that port is already in use by some + non-<productname>PostgreSQL</productname> process. You might also + get this error if you terminate <command>postgres</command> + 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 <quote>trusted</quote> and only permit + the Unix superuser to access them. + </para> + + </refsect1> + + <refsect1> + <title>Notes</title> + + <para> + The utility command <xref linkend="app-pg-ctl"/> can be used to + start and shut down the <command>postgres</command> server + safely and comfortably. + </para> + + <para> + If at all possible, <emphasis>do not</emphasis> use + <literal>SIGKILL</literal> to kill the main + <command>postgres</command> server. Doing so will prevent + <command>postgres</command> from freeing the system + resources (e.g., shared memory and semaphores) that it holds before + terminating. This might cause problems for starting a fresh + <command>postgres</command> run. + </para> + + <para> + To terminate the <command>postgres</command> server normally, the + signals <literal>SIGTERM</literal>, <literal>SIGINT</literal>, or + <literal>SIGQUIT</literal> 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. + </para> + + <para> + The <literal>SIGHUP</literal> signal will reload + the server configuration files. It is also possible to send + <literal>SIGHUP</literal> to an individual server process, but that + is usually not sensible. + </para> + + <para> + To cancel a running query, send the <literal>SIGINT</literal> signal + to the process running that command. To terminate a backend process + cleanly, send <literal>SIGTERM</literal> to that process. See + also <function>pg_cancel_backend</function> and <function>pg_terminate_backend</function> + in <xref linkend="functions-admin-signal"/> for the SQL-callable equivalents + of these two actions. + </para> + + <para> + The <command>postgres</command> server uses <literal>SIGQUIT</literal> + to tell subordinate server processes to terminate without normal + cleanup. + This signal <emphasis>should not</emphasis> be used by users. It + is also unwise to send <literal>SIGKILL</literal> to a server + process — the main <command>postgres</command> process will + interpret this as a crash and will force all the sibling processes + to quit as part of its standard crash-recovery procedure. + </para> + </refsect1> + + <refsect1 id="app-postgres-bugs"> + <title>Bugs</title> + <para> + The <option>--</option> options will not work on <systemitem + class="osname">FreeBSD</systemitem> or <systemitem class="osname">OpenBSD</systemitem>. + Use <option>-c</option> instead. This is a bug in the affected operating + systems; a future release of <productname>PostgreSQL</productname> + will provide a workaround if this is not fixed. + </para> + </refsect1> + + <refsect1 id="app-postgres-single-user" xreflabel="Single-User Mode"> + <title>Single-User Mode</title> + + <para> + To start a single-user mode server, use a command like +<screen> +<userinput>postgres --single -D /usr/local/pgsql/data <replaceable>other-options</replaceable> my_database</userinput> +</screen> + Provide the correct path to the database directory with <option>-D</option>, or + make sure that the environment variable <envar>PGDATA</envar> is set. + Also specify the name of the particular database you want to work in. + </para> + + <para> + Normally, the single-user mode server treats newline as the command + entry terminator; there is no intelligence about semicolons, + as there is in <application>psql</application>. 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. + </para> + + <para> + But if you use the <option>-j</option> 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. + </para> + + <para> + 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. + </para> + + <para> + To quit the session, type <acronym>EOF</acronym> + (<keycombo action="simul"><keycap>Control</keycap><keycap>D</keycap></keycombo>, usually). + If you've entered any text since the last command entry terminator, + then <acronym>EOF</acronym> will be taken as a command entry terminator, + and another <acronym>EOF</acronym> will be needed to exit. + </para> + + <para> + 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. + </para> + </refsect1> + + <refsect1 id="app-postgres-examples"> + <title>Examples</title> + + <para> + To start <command>postgres</command> in the background + using default values, type: + +<screen> +<prompt>$</prompt> <userinput>nohup postgres >logfile 2>&1 </dev/null &</userinput> +</screen> + </para> + + <para> + To start <command>postgres</command> with a specific + port, e.g., 1234: +<screen> +<prompt>$</prompt> <userinput>postgres -p 1234</userinput> +</screen> + To connect to this server using <application>psql</application>, specify this port with the -p option: +<screen> +<prompt>$</prompt> <userinput>psql -p 1234</userinput> +</screen> + or set the environment variable <envar>PGPORT</envar>: +<screen> +<prompt>$</prompt> <userinput>export PGPORT=1234</userinput> +<prompt>$</prompt> <userinput>psql</userinput> +</screen> + </para> + + <para> + Named run-time parameters can be set in either of these styles: +<screen> +<prompt>$</prompt> <userinput>postgres -c work_mem=1234</userinput> +<prompt>$</prompt> <userinput>postgres --work-mem=1234</userinput> +</screen> + Either form overrides whatever setting might exist for + <varname>work_mem</varname> in <filename>postgresql.conf</filename>. 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 + <filename>postgresql.conf</filename> than to rely on a command-line switch + to set a parameter. + </para> + </refsect1> + + <refsect1> + <title>See Also</title> + + <para> + <xref linkend="app-initdb"/>, + <xref linkend="app-pg-ctl"/> + </para> + </refsect1> +</refentry> |