database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-28 23:42:10 +03:00
Code Activity

Introduce file_copy_method setting.

Browse Source 
It can be set to either COPY (the default) or CLONE if the system
supports it.  CLONE causes callers of copydir(), currently CREATE
DATABASE ... STRATEGY=FILE_COPY and ALTER DATABASE ... SET TABLESPACE =
..., to use copy_file_range (Linux, FreeBSD) or copyfile (macOS) to copy
files instead of a read-write loop over the contents.

CLONE gives the kernel the opportunity to share block ranges on
copy-on-write file systems and push copying down to storage on others,
depending on configuration.  On some systems CLONE can be used to clone
large databases quickly with CREATE DATABASE ... TEMPLATE=source
STRATEGY=FILE_COPY.

Other operating systems could be supported; patches welcome.

Co-authored-by: Nazir Bilal Yavuz <byavuz81@gmail.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Ranier Vilela <ranier.vf@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKGLM%2Bt%2BSwBU-cHeMUXJCOgBxSHLGZutV5zCwY4qrCcE02w%40mail.gmail.com
This commit is contained in:
Thomas Munro
2025-04-08 20:52:47 +12:00
parent 042a66291b
commit f78ca6f3eb
9 changed files with 159 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
doc/src/sgml/config.sgml
View File

@ -2347,6 +2347,44 @@ include_dir 'conf.d'
</listitem>
</varlistentry>
<varlistentry id="guc_file_copy_method" xreflabel="file_copy_method">
<term><varname>file_copy_method</varname> (<type>enum</type>)
<indexterm>
<primary><varname>file_copy_method</varname> configuration parameter</primary>
</indexterm>
</term>
<listitem>
<para>
Specifies the method used to copy files.
Possible values are <literal>COPY</literal> (default) and
<literal>CLONE</literal> (if operating support is available).
</para>
<para>
This parameter affects:
</para>
<itemizedlist>
<listitem>
<para>
<literal><command>CREATE DATABASE ... STRATEGY=FILE_COPY</command></literal>
</para>
</listitem>
<listitem>
<para>
<command>ALTER DATABASE ... SET TABLESPACE ...</command>
</para>
</listitem>
</itemizedlist>
<para>
<literal>CLONE</literal> uses the <function>copy_file_range()</function>
(Linux, FreeBSD) or <function>copyfile</function>
(macOS) system calls, giving the kernel the opportunity to share disk
blocks or push work down to lower layers on some file systems.
</para>
</listitem>
</varlistentry>
<varlistentry id="guc-max-notify-queue-pages" xreflabel="max_notify_queue_pages">
<term><varname>max_notify_queue_pages</varname> (<type>integer</type>)
<indexterm>

3
doc/src/sgml/ref/alter_database.sgml
View File

@ -82,7 +82,8 @@ ALTER DATABASE <replaceable class="parameter">name</replaceable> RESET ALL
default tablespace to the new tablespace. The new default tablespace
must be empty for this database, and no one can be connected to
the database. Tables and indexes in non-default tablespaces are
unaffected.
unaffected. The method used to copy files to the new tablespace
is affected by the <xref glinkend="guc_file_copy_method"/> setting.
</para>
<para>

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

@ -138,7 +138,9 @@ CREATE DATABASE <replaceable class="parameter">name</replaceable>
log volume substantially, especially if the template database is large,
it also forces the system to perform a checkpoint both before and
after the creation of the new database. In some situations, this may
have a noticeable negative impact on overall system performance.
have a noticeable negative impact on overall system performance. The
<literal>FILE_COPY</literal> strategy is affected by the <xref
linkend="guc_file_copy_method"/> setting.
</para>
</listitem>
</varlistentry>