bb7520cc26
Before, some places didn't document the short options (-? and -V), some documented both, some documented nothing, and they were listed in various orders. Now this is hopefully more consistent and complete.
295 lines
9.2 KiB
Plaintext
295 lines
9.2 KiB
Plaintext
<!--
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doc/src/sgml/ref/pg_receivexlog.sgml
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PostgreSQL documentation
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-->
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<refentry id="app-pgreceivexlog">
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<refmeta>
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<refentrytitle>pg_receivexlog</refentrytitle>
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<manvolnum>1</manvolnum>
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<refmiscinfo>Application</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>pg_receivexlog</refname>
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<refpurpose>streams transaction logs from a <productname>PostgreSQL</productname> cluster</refpurpose>
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</refnamediv>
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<indexterm zone="app-pgreceivexlog">
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<primary>pg_receivexlog</primary>
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</indexterm>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>pg_receivexlog</command>
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<arg rep="repeat"><replaceable>option</></arg>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>
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Description
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</title>
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<para>
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<application>pg_receivexlog</application> is used to stream transaction log
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from a running <productname>PostgreSQL</productname> cluster. The transaction
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log is streamed using the streaming replication protocol, and is written
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to a local directory of files. This directory can be used as the archive
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location for doing a restore using point-in-time recovery (see
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<xref linkend="continuous-archiving">).
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</para>
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<para>
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<application>pg_receivexlog</application> streams the transaction
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log in real time as it's being generated on the server, and does not wait
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for segments to complete like <xref linkend="guc-archive-command"> does.
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For this reason, it is not necessary to set
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<xref linkend="guc-archive-timeout"> when using
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<application>pg_receivexlog</application>.
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</para>
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<para>
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The transaction log is streamed over a regular
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<productname>PostgreSQL</productname> connection, and uses the replication
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protocol. The connection must be made with a superuser or a user
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having <literal>REPLICATION</literal> permissions (see
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<xref linkend="role-attributes">), and <filename>pg_hba.conf</filename>
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must explicitly permit the replication connection. The server must also be
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configured with <xref linkend="guc-max-wal-senders"> set high enough to
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leave at least one session available for the stream.
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</para>
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<para>
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If the connection is lost, or if it cannot be initially established,
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with a non-fatal error, <application>pg_receivexlog</application> will
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retry the connection indefinitely, and reestablish streaming as soon
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as possible. To avoid this behavior, use the <literal>-n</literal>
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parameter.
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</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>
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The following command-line options control the location and format of the
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output.
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<variablelist>
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<varlistentry>
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<term><option>-D <replaceable class="parameter">directory</replaceable></option></term>
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<term><option>--directory=<replaceable class="parameter">directory</replaceable></option></term>
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<listitem>
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<para>
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Directory to write the output to.
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</para>
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<para>
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This parameter is required.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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The following command-line options control the running of the program.
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<variablelist>
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<varlistentry>
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<term><option>-n</option></term>
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<term><option>--noloop</option></term>
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<listitem>
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<para>
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Don't loop on connection errors. Instead, exit right away with
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an error.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-v</option></term>
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<term><option>--verbose</option></term>
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<listitem>
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<para>
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Enables verbose mode.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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The following command-line options control the database connection parameters.
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<variablelist>
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<varlistentry>
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<term><option>-s <replaceable class="parameter">interval</replaceable></option></term>
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<term><option>--statusint=<replaceable class="parameter">interval</replaceable></option></term>
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<listitem>
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<para>
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Specifies the number of seconds between status packets sent back to the
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server. This is required if replication timeout is configured on the
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server, and allows for easier monitoring. A value of zero disables the
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status updates completely. The default value is 10 seconds.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-h <replaceable class="parameter">host</replaceable></option></term>
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<term><option>--host=<replaceable class="parameter">host</replaceable></option></term>
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<listitem>
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<para>
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Specifies the host name of the machine on which the server is
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running. If the value begins with a slash, it is used as the
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directory for the Unix domain socket. The default is taken
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from the <envar>PGHOST</envar> environment variable, if set,
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else a Unix domain socket connection is attempted.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-p <replaceable class="parameter">port</replaceable></option></term>
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<term><option>--port=<replaceable class="parameter">port</replaceable></option></term>
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<listitem>
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<para>
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Specifies the TCP port or local Unix domain socket file
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extension on which the server is listening for connections.
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Defaults to the <envar>PGPORT</envar> environment variable, if
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set, or a compiled-in default.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-U <replaceable>username</replaceable></option></term>
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<term><option>--username=<replaceable class="parameter">username</replaceable></option></term>
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<listitem>
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<para>
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User name to connect as.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-w</></term>
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<term><option>--no-password</></term>
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<listitem>
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<para>
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Never issue a password prompt. If the server requires
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password authentication and a password is not available by
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other means such as a <filename>.pgpass</filename> file, the
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connection attempt will fail. This option can be useful in
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batch jobs and scripts where no user is present to enter a
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password.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-W</option></term>
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<term><option>--password</option></term>
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<listitem>
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<para>
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Force <application>pg_receivexlog</application> to prompt for a
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password before connecting to a database.
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</para>
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<para>
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This option is never essential, since
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<application>pg_receivexlog</application> will automatically prompt
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for a password if the server demands password authentication.
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However, <application>pg_receivexlog</application> will waste a
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connection attempt finding out that the server wants a password.
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In some cases it is worth typing <option>-W</> to avoid the extra
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connection attempt.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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Other options are also available:
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<variablelist>
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<varlistentry>
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<term><option>-V</></term>
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<term><option>--version</></term>
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<listitem>
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<para>
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Print the <application>pg_receivexlog</application> version and exit.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-?</></term>
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<term><option>--help</></term>
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<listitem>
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<para>
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Show help about <application>pg_receivexlog</application> command line
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arguments, and exit.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1>
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<title>Environment</title>
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<para>
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This utility, like most other <productname>PostgreSQL</> utilities,
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uses the environment variables supported by <application>libpq</>
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(see <xref linkend="libpq-envars">).
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</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>
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When using <application>pg_receivexlog</application> instead of
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<xref linkend="guc-archive-command">, the server will continue to
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recycle transaction log files even if the backups are not properly
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archived, since there is no command that fails. This can be worked
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around by having an <xref linkend="guc-archive-command"> that fails
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when the file has not been properly archived yet, for example:
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<programlisting>
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archive_command = 'sleep 5 && test -f /mnt/server/archivedir/%f'
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</programlisting>
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The initial timeout is necessary because
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<application>pg_receivexlog</application> works using asynchronous
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replication and can therefore be slightly behind the master.
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</para>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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<para>
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To stream the transaction log from the server at
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<literal>mydbserver</literal> and store it in the local directory
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<filename>/usr/local/pgsql/archive</filename>:
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<screen>
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<prompt>$</prompt> <userinput>pg_receivexlog -h mydbserver -D /usr/local/pgsql/archive</userinput>
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</screen></para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<simplelist type="inline">
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<member><xref linkend="APP-PGBASEBACKUP"></member>
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</simplelist>
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</refsect1>
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</refentry>
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