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This unifies the various ad hoc logging (message printing, error printing) systems used throughout the command-line programs. Features: - Program name is automatically prefixed. - Message string does not end with newline. This removes a common source of inconsistencies and omissions. - Additionally, a final newline is automatically stripped, simplifying use of PQerrorMessage() etc., another common source of mistakes. - I converted error message strings to use %m where possible. - As a result of the above several points, more translatable message strings can be shared between different components and between frontends and backend, without gratuitous punctuation or whitespace differences. - There is support for setting a "log level". This is not meant to be user-facing, but can be used internally to implement debug or verbose modes. - Lazy argument evaluation, so no significant overhead if logging at some level is disabled. - Some color in the messages, similar to gcc and clang. Set PG_COLOR=auto to try it out. Some colors are predefined, but can be customized by setting PG_COLORS. - Common files (common/, fe_utils/, etc.) can handle logging much more simply by just using one API without worrying too much about the context of the calling program, requiring callbacks, or having to pass "progname" around everywhere. - Some programs called setvbuf() to make sure that stderr is unbuffered, even on Windows. But not all programs did that. This is now done centrally. Soft goals: - Reduces vertical space use and visual complexity of error reporting in the source code. - Encourages more deliberate classification of messages. For example, in some cases it wasn't clear without analyzing the surrounding code whether a message was meant as an error or just an info. - Concepts and terms are vaguely aligned with popular logging frameworks such as log4j and Python logging. This is all just about printing stuff out. Nothing affects program flow (e.g., fatal exits). The uses are just too varied to do that. Some existing code had wrappers that do some kind of print-and-exit, and I adapted those. I tried to keep the output mostly the same, but there is a lot of historical baggage to unwind and special cases to consider, and I might not always have succeeded. One significant change is that pg_rewind used to write all error messages to stdout. That is now changed to stderr. Reviewed-by: Donald Dong <xdong@csumb.edu> Reviewed-by: Arthur Zakirov <a.zakirov@postgrespro.ru> Discussion: https://www.postgresql.org/message-id/flat/6a609b43-4f57-7348-6480-bd022f924310@2ndquadrant.com
436 lines
14 KiB
Plaintext
436 lines
14 KiB
Plaintext
<!--
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doc/src/sgml/ref/pg_recvlogical.sgml
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PostgreSQL documentation
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-->
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<refentry id="app-pgrecvlogical">
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<indexterm zone="app-pgrecvlogical">
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<primary>pg_recvlogical</primary>
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</indexterm>
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<refmeta>
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<refentrytitle><application>pg_recvlogical</application></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_recvlogical</refname>
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<refpurpose>control <productname>PostgreSQL</productname> logical decoding streams</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>pg_recvlogical</command>
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<arg rep="repeat" choice="opt"><replaceable>option</replaceable></arg>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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<command>pg_recvlogical</command> controls logical decoding replication
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slots and streams data from such replication slots.
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</para>
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<para>
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It creates a replication-mode connection, so it is subject to the same
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constraints as <xref linkend="app-pgreceivewal"/>, plus those for logical
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replication (see <xref linkend="logicaldecoding"/>).
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</para>
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<para>
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<command>pg_recvlogical</command> has no equivalent to the logical decoding
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SQL interface's peek and get modes. It sends replay confirmations for
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data lazily as it receives it and on clean exit. To examine pending data on
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a slot without consuming it, use
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<link linkend="functions-replication"><function>pg_logical_slot_peek_changes</function></link>.
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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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At least one of the following options must be specified to select an action:
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<variablelist>
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<varlistentry>
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<term><option>--create-slot</option></term>
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<listitem>
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<para>
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Create a new logical replication slot with the name specified by
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<option>--slot</option>, using the output plugin specified by
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<option>--plugin</option>, for the database specified
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by <option>--dbname</option>.
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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>--drop-slot</option></term>
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<listitem>
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<para>
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Drop the replication slot with the name specified
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by <option>--slot</option>, then 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>--start</option></term>
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<listitem>
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<para>
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Begin streaming changes from the logical replication slot specified
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by <option>--slot</option>, continuing until terminated by a
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signal. If the server side change stream ends with a server shutdown
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or disconnect, retry in a loop unless
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<option>--no-loop</option> is specified.
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</para>
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<para>
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The stream format is determined by the output plugin specified when
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the slot was created.
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</para>
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<para>
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The connection must be to the same database used to create the slot.
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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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<option>--create-slot</option> and <option>--start</option> can be
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specified together. <option>--drop-slot</option> cannot be combined with
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another action.
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</para>
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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 and other replication behavior:
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<variablelist>
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<varlistentry>
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<term><option>-E <replaceable>lsn</replaceable></option></term>
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<term><option>--endpos=<replaceable>lsn</replaceable></option></term>
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<listitem>
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<para>
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In <option>--start</option> mode, automatically stop replication
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and exit with normal exit status 0 when receiving reaches the
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specified LSN. If specified when not in <option>--start</option>
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mode, an error is raised.
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</para>
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<para>
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If there's a record with LSN exactly equal to <replaceable>lsn</replaceable>,
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the record will be output.
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</para>
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<para>
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The <option>--endpos</option> option is not aware of transaction
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boundaries and may truncate output partway through a transaction.
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Any partially output transaction will not be consumed and will be
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replayed again when the slot is next read from. Individual messages
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are never truncated.
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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>-f <replaceable>filename</replaceable></option></term>
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<term><option>--file=<replaceable>filename</replaceable></option></term>
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<listitem>
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<para>
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Write received and decoded transaction data into this
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file. Use <literal>-</literal> for <systemitem>stdout</systemitem>.
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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>-F <replaceable>interval_seconds</replaceable></option></term>
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<term><option>--fsync-interval=<replaceable>interval_seconds</replaceable></option></term>
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<listitem>
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<para>
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Specifies how often <application>pg_recvlogical</application> should
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issue <function>fsync()</function> calls to ensure the output file is
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safely flushed to disk.
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</para>
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<para>
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The server will occasionally request the client to perform a flush and
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report the flush position to the server. This setting is in addition
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to that, to perform flushes more frequently.
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</para>
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<para>
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Specifying an interval of <literal>0</literal> disables
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issuing <function>fsync()</function> calls altogether, while still
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reporting progress to the server. In this case, data could be lost in
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the event of a crash.
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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>-I <replaceable>lsn</replaceable></option></term>
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<term><option>--startpos=<replaceable>lsn</replaceable></option></term>
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<listitem>
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<para>
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In <option>--start</option> mode, start replication from the given
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LSN. For details on the effect of this, see the documentation
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in <xref linkend="logicaldecoding"/>
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and <xref linkend="protocol-replication"/>. Ignored in other modes.
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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>--if-not-exists</option></term>
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<listitem>
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<para>
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Do not error out when <option>--create-slot</option> is specified
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and a slot with the specified name already exists.
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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>-n</option></term>
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<term><option>--no-loop</option></term>
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<listitem>
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<para>
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When the connection to the server is lost, do not retry in a loop, just 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>-o <replaceable>name</replaceable>[=<replaceable>value</replaceable>]</option></term>
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<term><option>--option=<replaceable>name</replaceable>[=<replaceable>value</replaceable>]</option></term>
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<listitem>
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<para>
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Pass the option <replaceable>name</replaceable> to the output plugin with,
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if specified, the option value <replaceable>value</replaceable>. Which
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options exist and their effects depends on the used output plugin.
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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>plugin</replaceable></option></term>
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<term><option>--plugin=<replaceable>plugin</replaceable></option></term>
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<listitem>
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<para>
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When creating a slot, use the specified logical decoding output
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plugin. See <xref linkend="logicaldecoding"/>. This option has no
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effect if the slot already exists.
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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>-s <replaceable>interval_seconds</replaceable></option></term>
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<term><option>--status-interval=<replaceable>interval_seconds</replaceable></option></term>
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<listitem>
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<para>
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This option has the same effect as the option of the same name
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in <xref linkend="app-pgreceivewal"/>. See the description there.
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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>-S <replaceable>slot_name</replaceable></option></term>
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<term><option>--slot=<replaceable>slot_name</replaceable></option></term>
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<listitem>
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<para>
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In <option>--start</option> mode, use the existing logical replication slot named
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<replaceable>slot_name</replaceable>. In <option>--create-slot</option>
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mode, create the slot with this name. In <option>--drop-slot</option>
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mode, delete the slot with this name.
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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>-d <replaceable>database</replaceable></option></term>
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<term><option>--dbname=<replaceable>database</replaceable></option></term>
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<listitem>
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<para>
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The database to connect to. See the description of the actions for
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what this means in detail. This can be a <application>libpq</application> connection string;
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see <xref linkend="libpq-connstring"/> for more information. Defaults
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to user name.
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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>hostname-or-ip</replaceable></option></term>
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<term><option>--host=<replaceable>hostname-or-ip</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>port</replaceable></option></term>
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<term><option>--port=<replaceable>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>user</replaceable></option></term>
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<term><option>--username=<replaceable>user</replaceable></option></term>
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<listitem>
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<para>
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User name to connect as. Defaults to current operating system user
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name.
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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>--no-password</option></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_recvlogical</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_recvlogical</application> will automatically prompt
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for a password if the server demands password authentication.
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However, <application>pg_recvlogical</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</option> 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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The following additional options are available:
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<variablelist>
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<varlistentry>
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<term><option>-V</option></term>
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<term><option>--version</option></term>
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<listitem>
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<para>
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Print the <application>pg_recvlogical</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>-?</option></term>
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<term><option>--help</option></term>
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<listitem>
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<para>
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Show help about <application>pg_recvlogical</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</productname> utilities,
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uses the environment variables supported by <application>libpq</application>
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(see <xref linkend="libpq-envars"/>).
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</para>
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<para>
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The environment variable <envar>PG_COLOR</envar> specifies whether to use
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color in diagnostics messages. Possible values are
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<literal>always</literal>, <literal>auto</literal>,
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<literal>never</literal>.
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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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<application>pg_recvlogical</application> will preserve group permissions on
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the received WAL files if group permissions are enabled on the source
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cluster.
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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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See <xref linkend="logicaldecoding-example"/> for an example.
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</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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|
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<simplelist type="inline">
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<member><xref linkend="app-pgreceivewal"/></member>
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</simplelist>
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</refsect1>
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</refentry>
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