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Adjust documentation for syncfs().

Browse Source 
Commit 8c16ad3b43 created a new appendix for syncfs(), which is
excessive for such a small amount of content.  This commit moves
the description of the caveats to be aware of when using syncfs()
back to the documentation for recovery_init_sync_method.  The
documentation for the other utilities with syncfs() support now
directs readers to recovery_init_sync_method for information about
these caveats.

Reported-by: Peter Eisentraut, Robert Haas
Suggested-by: Robert Haas
Reviewed-by: Robert Haas
Discussion: https://postgr.es/m/42804669-7063-1320-ed37-3226d5f1067d%40eisentraut.org
Discussion: https://postgr.es/m/CA%2BTgmobUiqKr%2BZMCLc5Qap-sXBnjfGUU%2BZBmzYEjUuWyjsGr1g%40mail.gmail.com
This commit is contained in:
Nathan Bossart 2024-03-27 10:23:13 -05:00
parent de7e96bd0f
commit 44a4cca991
11 changed files with 24 additions and 55 deletions
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12
doc/src/sgml/config.sgml
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@ -10870,9 +10870,15 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
On Linux, <literal>syncfs</literal> may be used instead, to ask the
operating system to synchronize the file systems that contain the
data directory, the WAL files and each tablespace (but not any other
file systems that may be reachable through symbolic links). See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
file systems that may be reachable through symbolic links). This may
be a lot faster than the <literal>fsync</literal> setting, because it
doesn't need to open each file one by one. On the other hand, it may
be slower if a file system is shared by other applications that
modify a lot of files, since those files will also be written to disk.
Furthermore, on versions of Linux before 5.8, I/O errors encountered
while writing data to disk may not be reported to
<productname>PostgreSQL</productname>, and relevant error messages may
appear only in kernel logs.
</para>
<para>
This parameter can only be set in the

1
doc/src/sgml/filelist.sgml
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@ -182,7 +182,6 @@
<!ENTITY acronyms SYSTEM "acronyms.sgml">
<!ENTITY glossary SYSTEM "glossary.sgml">
<!ENTITY color SYSTEM "color.sgml">
<!ENTITY syncfs SYSTEM "syncfs.sgml">
<!ENTITY features-supported SYSTEM "features-supported.sgml">
<!ENTITY features-unsupported SYSTEM "features-unsupported.sgml">

1
doc/src/sgml/postgres.sgml
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@ -289,7 +289,6 @@ break is not needed in a wider output rendering.
&acronyms;
&glossary;
&color;
&syncfs;
&obsolete;
</part>

4
doc/src/sgml/ref/initdb.sgml
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@ -394,8 +394,8 @@ PostgreSQL documentation
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file systems that contain the
data directory, the WAL files, and each tablespace. See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
<xref linkend="guc-recovery-init-sync-method"/> for information about
the caveats to be aware of when using <literal>syncfs</literal>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.

4
doc/src/sgml/ref/pg_basebackup.sgml
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@ -642,8 +642,8 @@ PostgreSQL documentation
backup directory. When the plain format is used,
<command>pg_basebackup</command> will also synchronize the file systems
that contain the WAL files and each tablespace. See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
<xref linkend="guc-recovery-init-sync-method"/> for information about
the caveats to be aware of when using <literal>syncfs</literal>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.

4
doc/src/sgml/ref/pg_checksums.sgml
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@ -152,8 +152,8 @@ PostgreSQL documentation
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file systems that contain the
data directory, the WAL files, and each tablespace. See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
<xref linkend="guc-recovery-init-sync-method"/> for information about
the caveats to be aware of when using <literal>syncfs</literal>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.

4
doc/src/sgml/ref/pg_combinebackup.sgml
View File

@ -176,8 +176,8 @@ PostgreSQL documentation
backup directory. When the plain format is used,
<command>pg_combinebackup</command> will also synchronize the file systems
that contain the WAL files and each tablespace. See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
<xref linkend="guc-recovery-init-sync-method"/> for information about
the caveats to be aware of when using <literal>syncfs</literal>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.

5
doc/src/sgml/ref/pg_dump.sgml
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@ -1319,8 +1319,9 @@ PostgreSQL documentation
<para>
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file system that contains the
archive directory. See <xref linkend="syncfs"/> for more information
about using <function>syncfs()</function>.
archive directory. See <xref linkend="guc-recovery-init-sync-method"/>
for information about the caveats to be aware of when using
<literal>syncfs</literal>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used or

4
doc/src/sgml/ref/pg_rewind.sgml
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@ -297,8 +297,8 @@ PostgreSQL documentation
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file systems that contain the
data directory, the WAL files, and each tablespace. See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
<xref linkend="guc-recovery-init-sync-method"/> for information about
the caveats to be aware of when using <literal>syncfs</literal>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.

4
doc/src/sgml/ref/pgupgrade.sgml
View File

@ -204,8 +204,8 @@ PostgreSQL documentation
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file systems that contain the
upgraded cluster's data directory, its WAL files, and each tablespace.
See <xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
See <xref linkend="guc-recovery-init-sync-method"/> for information
about the caveats to be aware of when using <literal>syncfs</literal>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.

36
doc/src/sgml/syncfs.sgml
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@ -1,36 +0,0 @@
<!-- doc/src/sgml/syncfs.sgml -->
<appendix id="syncfs">
<title><function>syncfs()</function> Caveats</title>
<indexterm zone="syncfs">
<primary>syncfs</primary>
</indexterm>
<para>
On Linux <function>syncfs()</function> may be specified for some
configuration parameters (e.g.,
<xref linkend="guc-recovery-init-sync-method"/>), server applications (e.g.,
<application>pg_upgrade</application>), and client applications (e.g.,
<application>pg_basebackup</application>) that involve synchronizing many
files to disk. <function>syncfs()</function> is advantageous in many cases,
but there are some trade-offs to keep in mind.
</para>
<para>
Since <function>syncfs()</function> instructs the operating system to
synchronize a whole file system, it typically requires many fewer system
calls than using <function>fsync()</function> to synchronize each file one by
one. Therefore, using <function>syncfs()</function> may be a lot faster than
using <function>fsync()</function>. However, it may be slower if a file
system is shared by other applications that modify a lot of files, since
those files will also be written to disk.
</para>
<para>
Furthermore, on versions of Linux before 5.8, I/O errors encountered while
writing data to disk may not be reported to the calling program, and relevant
error messages may appear only in kernel logs.
</para>
</appendix>