133 lines
4.0 KiB
Plaintext
133 lines
4.0 KiB
Plaintext
<!--
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doc/src/sgml/ref/pg_walsummary.sgml
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PostgreSQL documentation
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-->
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<refentry id="app-pgwalsummary">
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<indexterm zone="app-pgwalsummary">
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<primary>pg_walsummary</primary>
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</indexterm>
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<refmeta>
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<refentrytitle><application>pg_walsummary</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_walsummary</refname>
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<refpurpose>print contents of WAL summary files</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>pg_walsummary</command>
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<arg rep="repeat" choice="opt"><replaceable>option</replaceable></arg>
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<arg rep="repeat"><replaceable>file</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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<application>pg_walsummary</application> is used to print the contents of
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WAL summary files. These binary files are found with the
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<literal>pg_wal/summaries</literal> subdirectory of the data directory,
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and can be converted to text using this tool. This is not ordinarily
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necessary, since WAL summary files primarily exist to support
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<link linkend="backup-incremental-backup">incremental backup</link>,
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but it may be useful for debugging purposes.
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</para>
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<para>
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A WAL summary file is indexed by tablespace OID, relation OID, and relation
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fork. For each relation fork, it stores the list of blocks that were
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modified by WAL within the range summarized in the file. It can also
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store a "limit block," which is 0 if the relation fork was created or
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truncated within the relevant WAL range, and otherwise the shortest length
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to which the relation fork was truncated. If the relation fork was not
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created, deleted, or truncated within the relevant WAL range, the limit
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block is undefined or infinite and will not be printed by this tool.
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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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<variablelist>
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<varlistentry>
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<term><option>-i</option></term>
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<term><option>--individual</option></term>
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<listitem>
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<para>
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By default, <literal>pg_walsummary</literal> prints one line of output
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for each range of one or more consecutive modified blocks. This can
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make the output a lot briefer, since a relation where all blocks from
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0 through 999 were modified will produce only one line of output rather
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than 1000 separate lines. This option requests a separate line of
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output for every modified block.
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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>-q</option></term>
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<term><option>--quiet</option></term>
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<listitem>
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<para>
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Do not print any output, except for errors. This can be useful
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when you want to know whether a WAL summary file can be successfully
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parsed but don't care about the contents.
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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>--version</option></term>
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<listitem>
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<para>
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Display version information, 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>-?</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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Shows help about <application>pg_walsummary</application> command line
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arguments, and exits.
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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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The environment variable <envar>PG_COLOR</envar> specifies whether to use
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color in diagnostic messages. Possible values are
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<literal>always</literal>, <literal>auto</literal> and
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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>See Also</title>
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<simplelist type="inline">
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<member><xref linkend="app-pgbasebackup"/></member>
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<member><xref linkend="app-pgcombinebackup"/></member>
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</simplelist>
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</refsect1>
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</refentry>
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