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<!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 16.3 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="28.4.6. Base Backup Progress Reporting">Section 28.4.6</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 WAL 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>,
<code class="literal">none</code> for no compression or an integer (no
compression if 0, <code class="literal">gzip</code> if greater than 0).
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>,
<code class="literal">long</code>, and <code class="literal">workers</code>.
The detail string cannot be used when the compression method
is specified as a plain integer.
</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="28.2.16. 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 and operating system files. 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">$</code> <strong class="userinput"><code>pg_basebackup -D - -Ft -X fetch | bzip2 > backup.tar.bz2</code></strong>
</pre><p>
(This command will fail if there are multiple tablespaces in the
database.)
</p><p>
To create a backup of a local database where the tablespace in
<code class="filename">/opt/ts</code> is relocated
to <code class="filename">./backup/ts</code>:
</p><pre class="screen">
<code class="prompt">$</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="28.4.6. Base Backup Progress Reporting">Section 28.4.6</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 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> <span class="application">pgbench</span></td></tr></table></div></body></html>