10000 Backend support for streaming base backups · postgres/postgres@0eb59c4 · GitHub
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Backend support for streaming base backups
Add BASE_BACKUP command to walsender, allowing it to stream a base backup to the client (in tar format). The syntax is still far from ideal, that will be fixed in the switch to use a proper grammar for walsender. No client included yet, will come as a separate commit. Magnus Hagander and Heikki Linnakangas
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  • doc/src/sgml
  • src
    • < 10000 div style="grid-area:spacer;display:flex">
      backend/replication
  • include/replication

    • 5 files changed

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    -1
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    ‎doc/src/sgml/protocol.sgml

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    @@ -1458,6 +1458,98 @@ The commands accepted in walsender mode are:
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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>BASE_BACKUP <replaceable>options</><literal>;</><replaceable>label</></term>
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    <listitem>
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    <para>
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    Instructs the server to start streaming a base backup.
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    The system will automatically be put in backup mode with the label
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    specified in <replaceable>label</> before the backup is started, and
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    taken out of it when the backup is complete. The following options
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    are accepted:
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    <variablelist>
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    <varlistentry>
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    <term><literal>PROGRESS</></term>
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    <listitem>
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    <para>
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    Request information required to generate a progress report. This will
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    send back an approximate size in the header of each tablespace, which
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    can be used to calculate how far along the stream is done. This is
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    calculated by enumerating all the file sizes once before the transfer
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    is even started, and may as such have a negative impact on the
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    performance - in particular it may take longer before the first data
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    is streamed. Since the database files can change during the backup,
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    the size is only approximate and may both grow and shrink between
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    the time of approximation and the sending of the actual files.
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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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    When the backup is started, the server will first send a header in
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    ordinary result set format, followed by one or more CopyResponse
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    results, one for PGDATA and one for each additional tablespace other
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    than <literal>pg_default</> and <literal>pg_global</>. The data in
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    the CopyResponse results will be a tar format (using ustar00
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    extensions) dump of the tablespace contents.
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    </para>
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    <para>
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    The header is an ordinary resultset with one row for each tablespace.
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    The fields in this row are:
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    <variablelist>
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    <varlistentry>
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    <term>spcoid</term>
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    <listitem>
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    <para>
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    The oid of the tablespace, or <literal>NULL</> if it's the base
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    directory.
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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>spclocation</term>
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    <listitem>
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    <para>
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    The full path of the tablespace directory, or <literal>NULL</>
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    if it's the base directory.
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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>size</term>
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    <listitem>
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    <para>
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    The approximate size of the tablespace, if progress report has
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    been requested; otherwise it's <literal>NULL</>.
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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 tar archive for the data directory and each tablespace will contain
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    all files in the directories, regardless of whether they are
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    <productname>PostgreSQL</> files or other files added to the same
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    directory. The only excluded files are:
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    <itemizedlist spacing="compact" mark="bullet">
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    <listitem>
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    <para>
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    <filename>postmaster.pid</>
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    </para>
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    </listitem>
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    <listitem>
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    <para>
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    <filename>pg_xlog</> (including subdirectories)
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    </para>
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    </listitem>
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    </itemizedlist>
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    Owner, group and file mode are set if the underlying filesystem on
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    the server supports it.
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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>

    ‎src/backend/replication/Makefile

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    @@ -12,6 +12,6 @@ subdir = src/backend/replication
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    top_builddir = ../../..
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    include $(top_builddir)/src/Makefile.global
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    15-
    OBJS = walsender.o walreceiverfuncs.o walreceiver.o
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    OBJS = walsender.o walreceiverfuncs.o walreceiver.o basebackup.o
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    include $(top_srcdir)/src/backend/common.mk

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