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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>pg_basebackup</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="app-pgamcheck.html" title="pg_amcheck" /><link rel="next" href="pgbench.html" title="pgbench" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center"><span class="application">pg_basebackup</span></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="app-pgamcheck.html" title="pg_amcheck">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="reference-client.html" title="PostgreSQL Client Applications">Up</a></td><th width="60%" align="center">PostgreSQL Client Applications</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.6 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="pgbench.html" title="pgbench">Next</a></td></tr></table><hr /></div><div class="refentry" id="APP-PGBASEBACKUP"><div class="titlepage"></div><a id="id-1.9.4.10.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle"><span class="application">pg_basebackup</span></span></h2><p>pg_basebackup — take a base backup of a <span class="productname">PostgreSQL</span> cluster</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="cmdsynopsis"><p id="id-1.9.4.10.4.1"><code class="command">pg_basebackup</code> [<em class="replaceable"><code>option</code></em>...]</p></div></div><div class="refsect1" id="id-1.9.4.10.5"><h2>Description</h2><p>
   <span class="application">pg_basebackup</span> is used to take a base backup of
   a running <span class="productname">PostgreSQL</span> database cluster. The backup
   is taken without affecting other clients of the database, and can be used
   both for point-in-time recovery (see <a class="xref" href="continuous-archiving.html" title="26.3. Continuous Archiving and Point-in-Time Recovery (PITR)">Section 26.3</a>)
   and as the starting point for a log-shipping or streaming-replication standby
   server (see <a class="xref" href="warm-standby.html" title="27.2. Log-Shipping Standby Servers">Section 27.2</a>).
  </p><p>
   <span class="application">pg_basebackup</span> makes an exact copy of the database
   cluster's files, while making sure the server is put into and
   out of backup mode automatically. Backups are always taken of the entire
   database cluster; it is not possible to back up individual databases or
   database objects. For selective backups, another tool such as
   <a class="xref" href="app-pgdump.html" title="pg_dump"><span class="refentrytitle"><span class="application">pg_dump</span></span></a> must be used.
  </p><p>
   The backup is made over a regular <span class="productname">PostgreSQL</span>
   connection that uses the replication protocol. The connection must be made
   with a user ID that has <code class="literal">REPLICATION</code> permissions
   (see <a class="xref" href="role-attributes.html" title="22.2. Role Attributes">Section 22.2</a>) or is a superuser,
   and <a class="link" href="auth-pg-hba-conf.html" title="21.1. The pg_hba.conf File"><code class="filename">pg_hba.conf</code></a>
   must permit the replication connection. The server must also be configured
   with <a class="xref" href="runtime-config-replication.html#GUC-MAX-WAL-SENDERS">max_wal_senders</a> set high enough to provide at
   least one walsender for the backup plus one for WAL streaming (if used).
  </p><p>
   There can be multiple <code class="command">pg_basebackup</code>s running at the same time, but it is usually
   better from a performance point of view to take only one backup, and copy
   the result.
  </p><p>
   <span class="application">pg_basebackup</span> can make a base backup from
   not only a primary server but also a standby. To take a backup from a standby,
   set up the standby so that it can accept replication connections (that is, set
   <code class="varname">max_wal_senders</code> and <a class="xref" href="runtime-config-replication.html#GUC-HOT-STANDBY">hot_standby</a>,
   and configure its <code class="filename">pg_hba.conf</code> appropriately).
   You will also need to enable <a class="xref" href="runtime-config-wal.html#GUC-FULL-PAGE-WRITES">full_page_writes</a> on the primary.
  </p><p>
   Note that there are some limitations in taking a backup from a standby:

   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
      The backup history file is not created in the database cluster backed up.
     </p></li><li class="listitem"><p>
      <span class="application">pg_basebackup</span> cannot force the standby
      to switch to a new WAL file at the end of backup.
      When you are using <code class="literal">-X none</code>, if write activity on
      the primary is low, <span class="application">pg_basebackup</span> may
      need to wait a long time for the last WAL file required for the backup
      to be switched and archived.  In this case, it may be useful to run
      <code class="function">pg_switch_wal</code> on the primary in order to
      trigger an immediate WAL file switch.
     </p></li><li class="listitem"><p>
      If the standby is promoted to be primary during backup, the backup fails.
     </p></li><li class="listitem"><p>
      All WAL records required for the backup must contain sufficient full-page writes,
      which requires you to enable <code class="varname">full_page_writes</code> on the primary.
     </p></li></ul></div><p>
  </p><p>
   Whenever <span class="application">pg_basebackup</span> is taking a base
   backup, the server's <code class="structname">pg_stat_progress_basebackup</code>
   view will report the progress of the backup.
   See <a class="xref" href="progress-reporting.html#BASEBACKUP-PROGRESS-REPORTING" title="28.4.5. Base Backup Progress Reporting">Section 28.4.5</a> for details.
  </p></div><div class="refsect1" id="id-1.9.4.10.6"><h2>Options</h2><p>
    The following command-line options control the location and format of the
    output:

    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="option">-D <em class="replaceable"><code>directory</code></em></code><br /></span><span class="term"><code class="option">--pgdata=<em class="replaceable"><code>directory</code></em></code></span></dt><dd><p>
        Sets the target directory to write the output to.
        <span class="application">pg_basebackup</span> will create this directory
        (and any missing parent directories) if it does not exist.  If it
        already exists, it must be empty.
       </p><p>
        When the backup is in tar format, the target directory may be
        specified as <code class="literal">-</code> (dash), causing the tar file to be
        written to <code class="literal">stdout</code>.
       </p><p>
        This option is required.
       </p></dd><dt><span class="term"><code class="option">-F <em class="replaceable"><code>format</code></em></code><br /></span><span class="term"><code class="option">--format=<em class="replaceable"><code>format</code></em></code></span></dt><dd><p>
        Selects the format for the output. <em class="replaceable"><code>format</code></em>
        can be one of the following:

        </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">p</code><br /></span><span class="term"><code class="literal">plain</code></span></dt><dd><p>
            Write the output as plain files, with the same layout as the
            source server's data directory and tablespaces. When the cluster has
            no additional tablespaces, the whole database will be placed in
            the target directory. If the cluster contains additional
            tablespaces, the main data directory will be placed in the
            target directory, but all other tablespaces will be placed
            in the same absolute path as they have on the source server.
            (See <code class="option">--tablespace-mapping</code> to change that.)
           </p><p>
            This is the default format.
           </p></dd><dt><span class="term"><code class="literal">t</code><br /></span><span class="term"><code class="literal">tar</code></span></dt><dd><p>
            Write the output as tar files in the target directory. The main
            data directory's contents will be written to a file named
            <code class="filename">base.tar</code>, and each other tablespace will be
            written to a separate tar file named after that tablespace's OID.
           </p><p>
            If the target directory is specified as <code class="literal">-</code>
            (dash), the tar contents will be written to
            standard output, suitable for piping to (for example)
            <span class="productname">gzip</span>. This is only allowed if
            the cluster has no additional tablespaces and WAL
            streaming is not used.
           </p></dd></dl></div></dd><dt><span class="term"><code class="option">-R</code><br /></span><span class="term"><code class="option">--write-recovery-conf</code></span></dt><dd><p>
        Creates a
        <a class="link" href="warm-standby.html#FILE-STANDBY-SIGNAL"><code class="filename">standby.signal</code></a>
        <a id="id-1.9.4.10.6.2.1.3.3.1.2" class="indexterm"></a>
        file and appends
        connection settings to the <code class="filename">postgresql.auto.conf</code>
        file in the target directory (or within the base archive file when
        using tar format).  This eases setting up a standby server using the
        results of the backup.
       </p><p>
        The <code class="filename">postgresql.auto.conf</code> file will record the connection
        settings and, if specified, the replication slot
        that <span class="application">pg_basebackup</span> is using, so that
        streaming replication will use the same settings later on.
       </p></dd><dt><span class="term"><code class="option">-t <em class="replaceable"><code>target</code></em></code><br /></span><span class="term"><code class="option">--target=<em class="replaceable"><code>target</code></em></code></span></dt><dd><p>
        Instructs the server where to place the base backup. The default target
        is <code class="literal">client</code>, which specifies that the backup should
        be sent to the machine where <span class="application">pg_basebackup</span>
        is running. If the target is instead set to
        <code class="literal">server:/some/path</code>, the backup will be stored on
        the machine where the server is running in the
        <code class="literal">/some/path</code> directory. Storing a backup on the
        server requires superuser privileges or having privileges of the
        <code class="literal">pg_write_server_files</code> role. If the target is set to
        <code class="literal">blackhole</code>, the contents are discarded and not
        stored anywhere. This should only be used for testing purposes, as you
        will not end up with an actual backup.
       </p><p>
        Since WAL streaming is implemented by
        <span class="application">pg_basebackup</span> rather than by the server,
        this option cannot be used together with <code class="literal">-Xstream</code>.
        Since that is the default, when this option is specified, you must also
        specify either <code class="literal">-Xfetch</code> or <code class="literal">-Xnone</code>.
       </p></dd><dt><span class="term"><code class="option">-T <em class="replaceable"><code>olddir</code></em>=<em class="replaceable"><code>newdir</code></em></code><br /></span><span class="term"><code class="option">--tablespace-mapping=<em class="replaceable"><code>olddir</code></em>=<em class="replaceable"><code>newdir</code></em></code></span></dt><dd><p>
        Relocates the tablespace in directory <em class="replaceable"><code>olddir</code></em>
        to <em class="replaceable"><code>newdir</code></em> during the backup.  To be
        effective, <em class="replaceable"><code>olddir</code></em> must exactly match the
        path specification of the tablespace as it is defined on the source
        server.  (But it is not an error if there is no tablespace
        in <em class="replaceable"><code>olddir</code></em> on the source server.)
        Meanwhile <em class="replaceable"><code>newdir</code></em> is a directory in the
        receiving host's filesystem.  As with the main target directory,
        <em class="replaceable"><code>newdir</code></em> need not exist already, but if
        it does exist it must be empty.
        Both <em class="replaceable"><code>olddir</code></em>
        and <em class="replaceable"><code>newdir</code></em> must be absolute paths.  If
        either path needs to contain an equal sign (<code class="literal">=</code>),
        precede that with a backslash.  This option can be specified multiple
        times for multiple tablespaces.
       </p><p>
        If a tablespace is relocated in this way, the symbolic links inside
        the main data directory are updated to point to the new location.  So
        the new data directory is ready to be used for a new server instance
        with all tablespaces in the updated locations.
       </p><p>
        Currently, this option only works with plain output format; it is
        ignored if tar format is selected.
       </p></dd><dt><span class="term"><code class="option">--waldir=<em class="replaceable"><code>waldir</code></em></code></span></dt><dd><p>
        Sets the directory to write WAL (write-ahead log) files to.
        By default WAL files will be placed in
        the <code class="filename">pg_wal</code> subdirectory of the target
        directory, but this option can be used to place them elsewhere.
        <em class="replaceable"><code>waldir</code></em> must be an absolute path.
        As with the main target directory,
        <em class="replaceable"><code>waldir</code></em> need not exist already, but if
        it does exist it must be empty.
        This option can only be specified when
        the backup is in plain format.
       </p></dd><dt><span class="term"><code class="option">-X <em class="replaceable"><code>method</code></em></code><br /></span><span class="term"><code class="option">--wal-method=<em class="replaceable"><code>method</code></em></code></span></dt><dd><p>
        Includes the required WAL (write-ahead log) files in the
        backup. This will include all write-ahead logs generated during
        the backup. Unless the method <code class="literal">none</code> is specified,
        it is possible to start a postmaster in the target
        directory without the need to consult the log archive, thus
        making the output a completely standalone backup.
       </p><p>
        The following <em class="replaceable"><code>method</code></em>s for collecting the
        write-ahead logs are supported:

        </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">n</code><br /></span><span class="term"><code class="literal">none</code></span></dt><dd><p>
            Don't include write-ahead logs in the backup.
           </p></dd><dt><span class="term"><code class="literal">f</code><br /></span><span class="term"><code class="literal">fetch</code></span></dt><dd><p>
            The write-ahead log files are collected at the end of the backup.
            Therefore, it is necessary for the source server's
            <a class="xref" href="runtime-config-replication.html#GUC-WAL-KEEP-SIZE">wal_keep_size</a> parameter to be set high
            enough that the required log data is not removed before the end
            of the backup.  If the required log data has been recycled
            before it's time to transfer it, the backup will fail and be
            unusable.
           </p><p>
            When tar format is used, the write-ahead log files will be
            included in the <code class="filename">base.tar</code> file.
           </p></dd><dt><span class="term"><code class="literal">s</code><br /></span><span class="term"><code class="literal">stream</code></span></dt><dd><p>
            Stream write-ahead log data while the backup is being taken.
            This method will open a second connection to the server and
            start streaming the write-ahead log in parallel while running
            the backup.  Therefore, it will require two replication
            connections not just one.  As long as the client can keep up
            with the write-ahead log data, using this method requires no
            extra write-ahead logs to be saved on the source server.
           </p><p>
            When tar format is used, the write-ahead log files will be
            written to a separate file named <code class="filename">pg_wal.tar</code>
            (if the server is a version earlier than 10, the file will be named
            <code class="filename">pg_xlog.tar</code>).
           </p><p>
            This value is the default.
           </p></dd></dl></div></dd><dt><span class="term"><code class="option">-z</code><br /></span><span class="term"><code class="option">--gzip</code></span></dt><dd><p>
        Enables gzip compression of tar file output, with the default
        compression level. Compression is only available when using
        the tar format, and the suffix <code class="filename">.gz</code> will
        automatically be added to all tar filenames.
       </p></dd><dt><span class="term"><code class="option">-Z <em class="replaceable"><code>level</code></em></code><br /></span><span class="term"><code class="option">-Z [{client|server}-]<em class="replaceable"><code>method</code></em>[:<em class="replaceable"><code>detail</code></em>]</code><br /></span><span class="term"><code class="option">--compress=<em class="replaceable"><code>level</code></em></code><br /></span><span class="term"><code class="option">--compress=[{client|server}-]<em class="replaceable"><code>method</code></em>[:<em class="replaceable"><code>detail</code></em>]</code></span></dt><dd><p>
        Requests compression of the backup. If <code class="literal">client</code> or
        <code class="literal">server</code> is included, it specifies where the
        compression is to be performed. Compressing on the server will reduce
        transfer bandwidth but will increase server CPU consumption.  The
        default is <code class="literal">client</code> except when
        <code class="literal">--target</code> is used. In that case, the backup is not
        being sent to the client, so only server compression is sensible.
        When <code class="literal">-Xstream</code>, which is the default, is used,
        server-side compression will not be applied to the WAL. To compress
        the WAL, use client-side compression, or
        specify <code class="literal">-Xfetch</code>.
       </p><p>
        The compression method can be set to <code class="literal">gzip</code>,
        <code class="literal">lz4</code>, <code class="literal">zstd</code>, or
        <code class="literal">none</code> for no compression. A compression detail
        string can optionally be specified.  If the detail string is an
        integer, it specifies the compression level.  Otherwise, it should be
        a comma-separated list of items, each of the form
        <code class="literal">keyword</code> or <code class="literal">keyword=value</code>.
        Currently, the supported keywords are <code class="literal">level</code>
        and <code class="literal">workers</code>.
       </p><p>
        If no compression level is specified, the default compression level
        will be used. If only a level is specified without mentioning an
        algorithm, <code class="literal">gzip</code> compression will be used if the
        level is greater than 0, and no compression will be used if the level
        is 0.
       </p><p>
        When the tar format is used with <code class="literal">gzip</code>,
        <code class="literal">lz4</code>, or <code class="literal">zstd</code>, the suffix
        <code class="filename">.gz</code>, <code class="filename">.lz4</code>, or
        <code class="filename">.zst</code>, respectively, will be automatically added to
        all tar filenames. When the plain format is used, client-side
        compression may not be specified, but it is still possible to request
        server-side compression. If this is done, the server will compress the
        backup for transmission, and the client will decompress and extract it.
       </p><p>
        When this option is used in combination with
        <code class="literal">-Xstream</code>, <code class="literal">pg_wal.tar</code> will
        be compressed using <code class="literal">gzip</code> if client-side gzip
        compression is selected, but will not be compressed if any other
        compression algorithm is selected, or if server-side compression
        is selected.
       </p></dd></dl></div><p>
   </p><p>
    The following command-line options control the generation of the
    backup and the invocation of the program:

    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="option">-c {fast|spread}</code><br /></span><span class="term"><code class="option">--checkpoint={fast|spread}</code></span></dt><dd><p>
        Sets checkpoint mode to fast (immediate) or spread (the default)
        (see <a class="xref" href="continuous-archiving.html#BACKUP-LOWLEVEL-BASE-BACKUP" title="26.3.3. Making a Base Backup Using the Low Level API">Section 26.3.3</a>).
       </p></dd><dt><span class="term"><code class="option">-C</code><br /></span><span class="term"><code class="option">--create-slot</code></span></dt><dd><p>
        Specifies that the replication slot named by the
        <code class="literal">--slot</code> option should be created before starting
        the backup.  An error is raised if the slot already exists.
       </p></dd><dt><span class="term"><code class="option">-l <em class="replaceable"><code>label</code></em></code><br /></span><span class="term"><code class="option">--label=<em class="replaceable"><code>label</code></em></code></span></dt><dd><p>
        Sets the label for the backup. If none is specified, a default value of
        <span class="quote"><span class="quote"><code class="literal">pg_basebackup base backup</code></span></span> will be used.
       </p></dd><dt><span class="term"><code class="option">-n</code><br /></span><span class="term"><code class="option">--no-clean</code></span></dt><dd><p>
        By default, when <code class="command">pg_basebackup</code> aborts with an
        error, it removes any directories it might have created before
        discovering that it cannot finish the job (for example, the target
        directory and write-ahead log directory). This option inhibits
        tidying-up and is thus useful for debugging.
       </p><p>
        Note that tablespace directories are not cleaned up either way.
       </p></dd><dt><span class="term"><code class="option">-N</code><br /></span><span class="term"><code class="option">--no-sync</code></span></dt><dd><p>
        By default, <code class="command">pg_basebackup</code> will wait for all files
        to be written safely to disk.  This option causes
        <code class="command">pg_basebackup</code> to return without waiting, which is
        faster, but means that a subsequent operating system crash can leave
        the base backup corrupt.  Generally, this option is useful for testing
        but should not be used when creating a production installation.
       </p></dd><dt><span class="term"><code class="option">-P</code><br /></span><span class="term"><code class="option">--progress</code></span></dt><dd><p>
        Enables progress reporting. Turning this on will deliver an approximate
        progress report during the backup. Since the database may change during
        the backup, this is only an approximation and may not end at exactly
        <code class="literal">100%</code>. In particular, when WAL log is included in the
        backup, the total amount of data cannot be estimated in advance, and
        in this case the estimated target size will increase once it passes the
        total estimate without WAL.
       </p></dd><dt><span class="term"><code class="option">-r <em class="replaceable"><code>rate</code></em></code><br /></span><span class="term"><code class="option">--max-rate=<em class="replaceable"><code>rate</code></em></code></span></dt><dd><p>
        Sets the maximum transfer rate at which data is collected from the
        source server.  This can be useful to limit the impact
        of <span class="application">pg_basebackup</span> on the server.  Values
        are in kilobytes per second.  Use a suffix of <code class="literal">M</code>
        to indicate megabytes per second.  A suffix of <code class="literal">k</code>
        is also accepted, and has no effect.  Valid values are between 32
        kilobytes per second and 1024 megabytes per second.
       </p><p>
        This option always affects transfer of the data directory. Transfer of
        WAL files is only affected if the collection method
        is <code class="literal">fetch</code>.
       </p></dd><dt><span class="term"><code class="option">-S <em class="replaceable"><code>slotname</code></em></code><br /></span><span class="term"><code class="option">--slot=<em class="replaceable"><code>slotname</code></em></code></span></dt><dd><p>
        This option can only be used together with <code class="literal">-X
        stream</code>.  It causes WAL streaming to use the specified
        replication slot.  If the base backup is intended to be used as a
        streaming-replication standby using a replication slot, the standby
        should then use the same replication slot name as
        <a class="xref" href="runtime-config-replication.html#GUC-PRIMARY-SLOT-NAME">primary_slot_name</a>.  This ensures that the
        primary server does not remove any necessary WAL data in the time
        between the end of the base backup and the start of streaming
        replication on the new standby.
       </p><p>
        The specified replication slot has to exist unless the
        option <code class="option">-C</code> is also used.
       </p><p>
        If this option is not specified and the server supports temporary
        replication slots (version 10 and later), then a temporary replication
        slot is automatically used for WAL streaming.
       </p></dd><dt><span class="term"><code class="option">-v</code><br /></span><span class="term"><code class="option">--verbose</code></span></dt><dd><p>
        Enables verbose mode. Will output some extra steps during startup and
        shutdown, as well as show the exact file name that is currently being
        processed if progress reporting is also enabled.
       </p></dd><dt><span class="term"><code class="option">--manifest-checksums=<em class="replaceable"><code>algorithm</code></em></code></span></dt><dd><p>
        Specifies the checksum algorithm that should be applied to each file
        included in the backup manifest. Currently, the available
        algorithms are <code class="literal">NONE</code>, <code class="literal">CRC32C</code>,
        <code class="literal">SHA224</code>, <code class="literal">SHA256</code>,
        <code class="literal">SHA384</code>, and <code class="literal">SHA512</code>.
        The default is <code class="literal">CRC32C</code>.
       </p><p>
        If <code class="literal">NONE</code> is selected, the backup manifest will
        not contain any checksums. Otherwise, it will contain a checksum
        of each file in the backup using the specified algorithm. In addition,
        the manifest will always contain a <code class="literal">SHA256</code>
        checksum of its own contents. The <code class="literal">SHA</code> algorithms
        are significantly more CPU-intensive than <code class="literal">CRC32C</code>,
        so selecting one of them may increase the time required to complete
        the backup.
       </p><p>
        Using a SHA hash function provides a cryptographically secure digest
        of each file for users who wish to verify that the backup has not been
        tampered with, while the CRC32C algorithm provides a checksum that is
        much faster to calculate; it is good at catching errors due to accidental
        changes but is not resistant to malicious modifications.  Note that, to
        be useful against an adversary who has access to the backup, the backup
        manifest would need to be stored securely elsewhere or otherwise
        verified not to have been modified since the backup was taken.
       </p><p>
        <a class="xref" href="app-pgverifybackup.html" title="pg_verifybackup"><span class="refentrytitle"><span class="application">pg_verifybackup</span></span></a> can be used to check the
        integrity of a backup against the backup manifest.
       </p></dd><dt><span class="term"><code class="option">--manifest-force-encode</code></span></dt><dd><p>
        Forces all filenames in the backup manifest to be hex-encoded.
        If this option is not specified, only non-UTF8 filenames are
        hex-encoded. This option is mostly intended to test that tools which
        read a backup manifest file properly handle this case.
       </p></dd><dt><span class="term"><code class="option">--no-estimate-size</code></span></dt><dd><p>
        Prevents the server from estimating the total
        amount of backup data that will be streamed, resulting in the
        <code class="structfield">backup_total</code> column in the
        <code class="structname">pg_stat_progress_basebackup</code> view
        always being <code class="literal">NULL</code>.
       </p><p>
        Without this option, the backup will start by enumerating
        the size of the entire database, and then go back and send
        the actual contents. This may make the backup take slightly
        longer, and in particular it will take longer before the first
        data is sent. This option is useful to avoid such estimation
        time if it's too long.
       </p><p>
        This option is not allowed when using <code class="option">--progress</code>.
       </p></dd><dt><span class="term"><code class="option">--no-manifest</code></span></dt><dd><p>
        Disables generation of a backup manifest. If this option is not
        specified, the server will generate and send a backup manifest
        which can be verified using <a class="xref" href="app-pgverifybackup.html" title="pg_verifybackup"><span class="refentrytitle"><span class="application">pg_verifybackup</span></span></a>.
        The manifest is a list of every file present in the backup with the
        exception of any WAL files that may be included. It also stores the
        size, last modification time, and an optional checksum for each file.
       </p></dd><dt><span class="term"><code class="option">--no-slot</code></span></dt><dd><p>
        Prevents the creation of a temporary replication slot
        for the backup.
       </p><p>
        By default, if log streaming is selected but no slot name is given
        with the <code class="option">-S</code> option, then a temporary replication
        slot is created (if supported by the source server).
       </p><p>
        The main purpose of this option is to allow taking a base backup when
        the server has no free replication slots.  Using a replication slot
        is almost always preferred, because it prevents needed WAL from being
        removed by the server during the backup.
       </p></dd><dt><span class="term"><code class="option">--no-verify-checksums</code></span></dt><dd><p>
        Disables verification of checksums, if they are enabled on the server
        the base backup is taken from.
       </p><p>
        By default, checksums are verified and checksum failures will result
        in a non-zero exit status. However, the base backup will not be
        removed in such a case, as if the <code class="option">--no-clean</code> option
        had been used.  Checksum verification failures will also be reported
        in the <a class="link" href="monitoring-stats.html#MONITORING-PG-STAT-DATABASE-VIEW" title="28.2.15. pg_stat_database">
        <code class="structname">pg_stat_database</code></a> view.
       </p></dd></dl></div><p>
   </p><p>
    The following command-line options control the connection to the source
    server:

    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="option">-d <em class="replaceable"><code>connstr</code></em></code><br /></span><span class="term"><code class="option">--dbname=<em class="replaceable"><code>connstr</code></em></code></span></dt><dd><p>
        Specifies parameters used to connect to the server, as a <a class="link" href="libpq-connect.html#LIBPQ-CONNSTRING" title="34.1.1. Connection Strings">connection string</a>;  these
        will override any conflicting command line options.
       </p><p>
        The option is called <code class="literal">--dbname</code> for consistency with other
        client applications, but because <span class="application">pg_basebackup</span>
        doesn't connect to any particular database in the cluster, any database
        name in the connection string will be ignored.
       </p></dd><dt><span class="term"><code class="option">-h <em class="replaceable"><code>host</code></em></code><br /></span><span class="term"><code class="option">--host=<em class="replaceable"><code>host</code></em></code></span></dt><dd><p>
        Specifies the host name of the machine on which the server is
        running.  If the value begins with a slash, it is used as the
        directory for a Unix domain socket. The default is taken
        from the <code class="envar">PGHOST</code> environment variable, if set,
        else a Unix domain socket connection is attempted.
       </p></dd><dt><span class="term"><code class="option">-p <em class="replaceable"><code>port</code></em></code><br /></span><span class="term"><code class="option">--port=<em class="replaceable"><code>port</code></em></code></span></dt><dd><p>
        Specifies the TCP port or local Unix domain socket file
        extension on which the server is listening for connections.
        Defaults to the <code class="envar">PGPORT</code> environment variable, if
        set, or a compiled-in default.
       </p></dd><dt><span class="term"><code class="option">-s <em class="replaceable"><code>interval</code></em></code><br /></span><span class="term"><code class="option">--status-interval=<em class="replaceable"><code>interval</code></em></code></span></dt><dd><p>
        Specifies the number of seconds between status packets sent back to
        the source server. Smaller values allow more accurate monitoring of
        backup progress from the server.
        A value of zero disables periodic status updates completely,
        although an update will still be sent when requested by the server, to
        avoid timeout-based disconnects. The default value is 10 seconds.
       </p></dd><dt><span class="term"><code class="option">-U <em class="replaceable"><code>username</code></em></code><br /></span><span class="term"><code class="option">--username=<em class="replaceable"><code>username</code></em></code></span></dt><dd><p>
        Specifies the user name to connect as.
       </p></dd><dt><span class="term"><code class="option">-w</code><br /></span><span class="term"><code class="option">--no-password</code></span></dt><dd><p>
        Prevents issuing a password prompt.  If the server requires
        password authentication and a password is not available by
        other means such as a <code class="filename">.pgpass</code> file, the
        connection attempt will fail.  This option can be useful in
        batch jobs and scripts where no user is present to enter a
        password.
       </p></dd><dt><span class="term"><code class="option">-W</code><br /></span><span class="term"><code class="option">--password</code></span></dt><dd><p>
        Forces <span class="application">pg_basebackup</span> to prompt for a
        password before connecting to the source server.
       </p><p>
        This option is never essential, since
        <span class="application">pg_basebackup</span> will automatically prompt
        for a password if the server demands password authentication.
        However, <span class="application">pg_basebackup</span> will waste a
        connection attempt finding out that the server wants a password.
        In some cases it is worth typing <code class="option">-W</code> to avoid the extra
        connection attempt.
       </p></dd></dl></div><p>
   </p><p>
    Other options are also available:

    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="option">-V</code><br /></span><span class="term"><code class="option">--version</code></span></dt><dd><p>
       Prints the <span class="application">pg_basebackup</span> version and exits.
       </p></dd><dt><span class="term"><code class="option">-?</code><br /></span><span class="term"><code class="option">--help</code></span></dt><dd><p>
       Shows help about <span class="application">pg_basebackup</span> command line
       arguments, and exits.
       </p></dd></dl></div><p>
   </p></div><div class="refsect1" id="id-1.9.4.10.7"><h2>Environment</h2><p>
   This utility, like most other <span class="productname">PostgreSQL</span> utilities,
   uses the environment variables supported by <span class="application">libpq</span>
   (see <a class="xref" href="libpq-envars.html" title="34.15. Environment Variables">Section 34.15</a>).
  </p><p>
   The environment variable <code class="envar">PG_COLOR</code> specifies whether to use
   color in diagnostic messages. Possible values are
   <code class="literal">always</code>, <code class="literal">auto</code> and
   <code class="literal">never</code>.
  </p></div><div class="refsect1" id="id-1.9.4.10.8"><h2>Notes</h2><p>
   At the beginning of the backup, a checkpoint needs to be performed on the
   source server.  This can take some time (especially if the option
   <code class="literal">--checkpoint=fast</code> is not used), during
   which <span class="application">pg_basebackup</span> will appear to be idle.
  </p><p>
   The backup will include all files in the data directory and tablespaces,
   including the configuration files and any additional files placed in the
   directory by third parties, except certain temporary files managed by
   PostgreSQL.  But only regular files and directories are copied, except that
   symbolic links used for tablespaces are preserved.  Symbolic links pointing
   to certain directories known to PostgreSQL are copied as empty directories.
   Other symbolic links and special device files are skipped.
   See <a class="xref" href="protocol-replication.html" title="55.4. Streaming Replication Protocol">Section 55.4</a> for the precise details.
  </p><p>
   In plain format, tablespaces will be backed up to the same path
   they have on the source server, unless the
   option <code class="literal">--tablespace-mapping</code> is used.  Without
   this option, running a plain format base backup on the same host as the
   server will not work if tablespaces are in use, because the backup would
   have to be written to the same directory locations as the original
   tablespaces.
  </p><p>
   When tar format is used, it is the user's responsibility to unpack each
   tar file before starting a PostgreSQL server that uses the data. If there
   are additional tablespaces, the
   tar files for them need to be unpacked in the correct locations. In this
   case the symbolic links for those tablespaces will be created by the server
   according to the contents of the <code class="filename">tablespace_map</code> file that is
   included in the <code class="filename">base.tar</code> file.
  </p><p>
   <span class="application">pg_basebackup</span> works with servers of the same
   or an older major version, down to 9.1. However, WAL streaming mode (<code class="literal">-X
   stream</code>) only works with server version 9.3 and later, and tar format
   (<code class="literal">--format=tar</code>) only works with server version 9.5
   and later.
  </p><p>
   <span class="application">pg_basebackup</span> will preserve group permissions
   for data files if group permissions are enabled on the source cluster.
  </p></div><div class="refsect1" id="id-1.9.4.10.9"><h2>Examples</h2><p>
   To create a base backup of the server at <code class="literal">mydbserver</code>
   and store it in the local directory
   <code class="filename">/usr/local/pgsql/data</code>:
</p><pre class="screen">
<code class="prompt">$</code> <strong class="userinput"><code>pg_basebackup -h mydbserver -D /usr/local/pgsql/data</code></strong>
</pre><p>
  </p><p>
   To create a backup of the local server with one compressed
   tar file for each tablespace, and store it in the directory
   <code class="filename">backup</code>, showing a progress report while running:
</p><pre class="screen">
<code class="prompt">$</code> <strong class="userinput"><code>pg_basebackup -D backup -Ft -z -P</code></strong>
</pre><p>
  </p><p>
   To create a backup of a single-tablespace local database and compress
   this with <span class="productname">bzip2</span>:
</p><pre class="screen">
<code class="prompt">$</code> <strong class="userinput"><code>pg_basebackup -D - -Ft -X fetch | bzip2 &gt; backup.tar.bz2</code></strong>
</pre><p>
   (This command will fail if there are multiple tablespaces in the
   database.)
  </p><p>
   To create a backup of a local database where the tablespace in
   <code class="filename">/opt/ts</code> is relocated
   to <code class="filename">./backup/ts</code>:
</p><pre class="screen">
<code class="prompt">$</code> <strong class="userinput"><code>pg_basebackup -D backup/data -T /opt/ts=$(pwd)/backup/ts</code></strong>
</pre><p>
   To create a backup of a local server with one tar file for each tablespace
   compressed with <span class="application">gzip</span> at level 9, stored in the
   directory <code class="filename">backup</code>:
</p><pre class="screen">
<code class="prompt">$</code> <strong class="userinput"><code>pg_basebackup -D backup -Ft --compress=gzip:9</code></strong>
</pre></div><div class="refsect1" id="id-1.9.4.10.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="app-pgdump.html" title="pg_dump"><span class="refentrytitle"><span class="application">pg_dump</span></span></a>, <a class="xref" href="progress-reporting.html#BASEBACKUP-PROGRESS-REPORTING" title="28.4.5. Base Backup Progress Reporting">Section 28.4.5</a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="app-pgamcheck.html" title="pg_amcheck">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="reference-client.html" title="PostgreSQL Client Applications">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="pgbench.html" title="pgbench">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="application">pg_amcheck</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.6 Documentation">Home</a></td><td width="40%" align="right" valign="top"> <span class="application">pgbench</span></td></tr></table></div></body></html>