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><H1
><A
NAME="APP-PGBASEBACKUP"
></A
>pg_basebackup</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN81651"
></A
><H2
>Name</H2
>pg_basebackup -- take a base backup of a <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> cluster</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN81657"
></A
><H2
>Synopsis</H2
><P
><TT
CLASS="COMMAND"
>pg_basebackup</TT
> [<TT
CLASS="REPLACEABLE"
><I
>option</I
></TT
>...]</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN81662"
></A
><H2
> Description
</H2
><P
> <SPAN
CLASS="APPLICATION"
>pg_basebackup</SPAN
> is used to take base backups of
a running <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> database cluster. These
are taken without affecting other clients to the database, and can be used
both for point-in-time recovery (see <A
HREF="continuous-archiving.html"
>Section 24.3</A
>)
and as the starting point for a log shipping or streaming replication standby
servers (see <A
HREF="warm-standby.html"
>Section 25.2</A
>).
</P
><P
> <SPAN
CLASS="APPLICATION"
>pg_basebackup</SPAN
> makes a binary copy of the database
cluster files, while making sure the system is put in 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 individual database backups, a tool such as
<A
HREF="app-pgdump.html"
>pg_dump</A
> must be used.
</P
><P
> The backup is made over a regular <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
connection, and uses the replication protocol. The connection must be made
with a superuser or a user having <TT
CLASS="LITERAL"
>REPLICATION</TT
>
permissions (see <A
HREF="role-attributes.html"
>Section 20.2</A
>),
and <TT
CLASS="FILENAME"
>pg_hba.conf</TT
> must explicitly permit the replication
connection. The server must also be configured
with <A
HREF="runtime-config-replication.html#GUC-MAX-WAL-SENDERS"
>max_wal_senders</A
> set high enough to leave at least
one session available for the backup.
</P
><P
> There can be multiple <TT
CLASS="COMMAND"
>pg_basebackup</TT
>s running at the same time, but it is
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 the master but also the standby. To take a backup from the standby,
set up the standby so that it can accept replication connections (that is, set
<TT
CLASS="VARNAME"
>max_wal_senders</TT
> and <A
HREF="runtime-config-replication.html#GUC-HOT-STANDBY"
>hot_standby</A
>,
and configure <A
HREF="auth-pg-hba-conf.html"
>host-based authentication</A
>).
You will also need to enable <A
HREF="runtime-config-wal.html#GUC-FULL-PAGE-WRITES"
>full_page_writes</A
> on the master.
</P
><P
> Note that there are some limitations in an online backup from the standby:
<P
></P
></P><UL
><LI
><P
> The backup history file is not created in the database cluster backed up.
</P
></LI
><LI
><P
> There is no guarantee that all WAL files required for the backup are archived
at the end of backup. If you are planning to use the backup for an archive
recovery and want to ensure that all required files are available at that moment,
you need to include them into the backup by using the <TT
CLASS="LITERAL"
>-x</TT
> option.
</P
></LI
><LI
><P
> If the standby is promoted to the master during online backup, the backup fails.
</P
></LI
><LI
><P
> All WAL records required for the backup must contain sufficient full-page writes,
which requires you to enable <TT
CLASS="VARNAME"
>full_page_writes</TT
> on the master and
not to use a tool like <SPAN
CLASS="APPLICATION"
>pg_compresslog</SPAN
> as
<TT
CLASS="VARNAME"
>archive_command</TT
> to remove full-page writes from WAL files.
</P
></LI
></UL
><P>
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN81700"
></A
><H2
>Options</H2
><P
> The following command-line options control the location and format of the
output.
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="OPTION"
>-D <TT
CLASS="REPLACEABLE"
><I
>directory</I
></TT
></TT
><BR><TT
CLASS="OPTION"
>--pgdata=<TT
CLASS="REPLACEABLE"
><I
>directory</I
></TT
></TT
></DT
><DD
><P
> Directory to write the output to.
<SPAN
CLASS="APPLICATION"
>pg_basebackup</SPAN
> will create the directory and
any parent directories if necessary. The directory may already exist,
but it is an error if the directory already exists and is not empty.
</P
><P
> When the backup is in tar mode, and the directory is specified as
<TT
CLASS="LITERAL"
>-</TT
> (dash), the tar file will be written to
<TT
CLASS="LITERAL"
>stdout</TT
>.
</P
><P
> This option is required.
</P
></DD
><DT
><TT
CLASS="OPTION"
>-F <TT
CLASS="REPLACEABLE"
><I
>format</I
></TT
></TT
><BR><TT
CLASS="OPTION"
>--format=<TT
CLASS="REPLACEABLE"
><I
>format</I
></TT
></TT
></DT
><DD
><P
> Selects the format for the output. <TT
CLASS="REPLACEABLE"
><I
>format</I
></TT
>
can be one of the following:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>p</TT
><BR><TT
CLASS="LITERAL"
>plain</TT
></DT
><DD
><P
> Write the output as plain files, with the same layout as the
current 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 server.
</P
><P
> This is the default format.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>t</TT
><BR><TT
CLASS="LITERAL"
>tar</TT
></DT
><DD
><P
> Write the output as tar files in the target directory. The main
data directory will be written to a file named
<TT
CLASS="FILENAME"
>base.tar</TT
>, and all other tablespaces will
be named after the tablespace OID.
</P
><P
> If the value <TT
CLASS="LITERAL"
>-</TT
> (dash) is specified as
target directory, the tar contents will be written to
standard output, suitable for piping to for example
<SPAN
CLASS="PRODUCTNAME"
>gzip</SPAN
>. This is only possible if
the cluster has no additional tablespaces.
</P
></DD
></DL
></DIV
><P></P
></DD
><DT
><TT
CLASS="OPTION"
>-x</TT
><BR><TT
CLASS="OPTION"
>--xlog</TT
></DT
><DD
><P
> Using this option is equivalent of using <TT
CLASS="LITERAL"
>-X</TT
> with
method <TT
CLASS="LITERAL"
>fetch</TT
>.
</P
></DD
><DT
><TT
CLASS="OPTION"
>-X <TT
CLASS="REPLACEABLE"
><I
>method</I
></TT
></TT
><BR><TT
CLASS="OPTION"
>--xlog-method=<TT
CLASS="REPLACEABLE"
><I
>method</I
></TT
></TT
></DT
><DD
><P
> Includes the required transaction log files (WAL files) in the
backup. This will include all transaction logs generated during
the backup. If this option is specified, it is possible to start
a postmaster directly in the extracted directory without the need
to consult the log archive, thus making this a completely standalone
backup.
</P
><P
> The following methods for collecting the transaction logs are
supported:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>f</TT
><BR><TT
CLASS="LITERAL"
>fetch</TT
></DT
><DD
><P
> The transaction log files are collected at the end of the backup.
Therefore, it is necessary for the
<A
HREF="runtime-config-replication.html#GUC-WAL-KEEP-SEGMENTS"
>wal_keep_segments</A
> parameter to be set high
enough that the log is not removed before the end of the backup.
If the log has been rotated when it's time to transfer it, the
backup will fail and be unusable.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>s</TT
><BR><TT
CLASS="LITERAL"
>stream</TT
></DT
><DD
><P
> Stream the transaction log while the backup is created. This will
open a second connection to the server and start streaming the
transaction log in parallel while running the backup. Therefore,
it will use up two slots configured by the
<A
HREF="runtime-config-replication.html#GUC-MAX-WAL-SENDERS"
>max_wal_senders</A
> parameter. As long as the
client can keep up with transaction log received, using this mode
requires no extra transaction logs to be saved on the master.
</P
></DD
></DL
></DIV
><P>
</P
></DD
><DT
><TT
CLASS="OPTION"
>-z</TT
><BR><TT
CLASS="OPTION"
>--gzip</TT
></DT
><DD
><P
> Enables gzip compression of tar file output, with the default
compression level. Compression is only available when using
the tar format.
</P
></DD
><DT
><TT
CLASS="OPTION"
>-Z <TT
CLASS="REPLACEABLE"
><I
>level</I
></TT
></TT
><BR><TT
CLASS="OPTION"
>--compress=<TT
CLASS="REPLACEABLE"
><I
>level</I
></TT
></TT
></DT
><DD
><P
> Enables gzip compression of tar file output, and specifies the
compression level (0 through 9, 0 being no compression and 9 being best
compression). Compression is only available when using the tar
format.
</P
></DD
></DL
></DIV
><P>
</P
><P
> The following command-line options control the generation of the
backup and the running of the program.
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="OPTION"
>-c <TT
CLASS="REPLACEABLE"
><I
>fast|spread</I
></TT
></TT
><BR><TT
CLASS="OPTION"
>--checkpoint=<TT
CLASS="REPLACEABLE"
><I
>fast|spread</I
></TT
></TT
></DT
><DD
><P
> Sets checkpoint mode to fast or spread (default).
</P
></DD
><DT
><TT
CLASS="OPTION"
>-l <TT
CLASS="REPLACEABLE"
><I
>label</I
></TT
></TT
><BR><TT
CLASS="OPTION"
>--label=<TT
CLASS="REPLACEABLE"
><I
>label</I
></TT
></TT
></DT
><DD
><P
> Sets the label for the backup. If none is specified, a default value of
<SPAN
CLASS="QUOTE"
>"<TT
CLASS="LITERAL"
>pg_basebackup base backup</TT
>"</SPAN
> will be used.
</P
></DD
><DT
><TT
CLASS="OPTION"
>-P</TT
><BR><TT
CLASS="OPTION"
>--progress</TT
></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
<TT
CLASS="LITERAL"
>100%</TT
>. 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
><P
> When this is enabled, 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.
</P
></DD
><DT
><TT
CLASS="OPTION"
>-v</TT
><BR><TT
CLASS="OPTION"
>--verbose</TT
></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
></DL
></DIV
><P>
</P
><P
> The following command-line options control the database connection parameters.
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="OPTION"
>-h <TT
CLASS="REPLACEABLE"
><I
>host</I
></TT
></TT
><BR><TT
CLASS="OPTION"
>--host=<TT
CLASS="REPLACEABLE"
><I
>host</I
></TT
></TT
></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 the Unix domain socket. The default is taken
from the <TT
CLASS="ENVAR"
>PGHOST</TT
> environment variable, if set,
else a Unix domain socket connection is attempted.
</P
></DD
><DT
><TT
CLASS="OPTION"
>-p <TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
></TT
><BR><TT
CLASS="OPTION"
>--port=<TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
></TT
></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 <TT
CLASS="ENVAR"
>PGPORT</TT
> environment variable, if
set, or a compiled-in default.
</P
></DD
><DT
><TT
CLASS="OPTION"
>-s <TT
CLASS="REPLACEABLE"
><I
>interval</I
></TT
></TT
><BR><TT
CLASS="OPTION"
>--status-interval=<TT
CLASS="REPLACEABLE"
><I
>interval</I
></TT
></TT
></DT
><DD
><P
> Specifies the number of seconds between status packets sent back to the
server. This is required when streaming the transaction log (using
<TT
CLASS="LITERAL"
>--xlog=stream</TT
>) if replication timeout is configured
on the server, and allows for easier monitoring. A value of zero disables
the status updates completely. The default value is 10 seconds.
</P
></DD
><DT
><TT
CLASS="OPTION"
>-U <TT
CLASS="REPLACEABLE"
><I
>username</I
></TT
></TT
><BR><TT
CLASS="OPTION"
>--username=<TT
CLASS="REPLACEABLE"
><I
>username</I
></TT
></TT
></DT
><DD
><P
> User name to connect as.
</P
></DD
><DT
><TT
CLASS="OPTION"
>-w</TT
><BR><TT
CLASS="OPTION"
>--no-password</TT
></DT
><DD
><P
> Never issue a password prompt. If the server requires
password authentication and a password is not available by
other means such as a <TT
CLASS="FILENAME"
>.pgpass</TT
> 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
><TT
CLASS="OPTION"
>-W</TT
><BR><TT
CLASS="OPTION"
>--password</TT
></DT
><DD
><P
> Force <SPAN
CLASS="APPLICATION"
>pg_basebackup</SPAN
> to prompt for a
password before connecting to a database.
</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 <TT
CLASS="OPTION"
>-W</TT
> to avoid the extra
connection attempt.
</P
></DD
></DL
></DIV
><P>
</P
><P
> Other options are also available:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="OPTION"
>-V</TT
><BR><TT
CLASS="OPTION"
>--version</TT
></DT
><DD
><P
> Print the <SPAN
CLASS="APPLICATION"
>pg_basebackup</SPAN
> version and exit.
</P
></DD
><DT
><TT
CLASS="OPTION"
>-?</TT
><BR><TT
CLASS="OPTION"
>--help</TT
></DT
><DD
><P
> Show help about <SPAN
CLASS="APPLICATION"
>pg_basebackup</SPAN
> command line
arguments, and exit.
</P
></DD
></DL
></DIV
><P>
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN81917"
></A
><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
HREF="libpq-envars.html"
>Section 31.14</A
>).
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN81923"
></A
><H2
>Notes</H2
><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. Only regular files and directories are allowed
in the data directory, no symbolic links or special device files.
</P
><P
> The way <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> manages tablespaces, the path
for all additional tablespaces must be identical whenever a backup is
restored. The main data directory, however, is relocatable to any location.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN81928"
></A
><H2
>Examples</H2
><P
> To create a base backup of the server at <TT
CLASS="LITERAL"
>mydbserver</TT
>
and store it in the local directory
<TT
CLASS="FILENAME"
>/usr/local/pgsql/data</TT
>:
</P><PRE
CLASS="SCREEN"
><SAMP
CLASS="PROMPT"
>$</SAMP
> <KBD
CLASS="USERINPUT"
>pg_basebackup -h mydbserver -D /usr/local/pgsql/data</KBD
></PRE
><P>
</P
><P
> To create a backup of the local server with one compressed
tar file for each tablespace, and store it in the directory
<TT
CLASS="FILENAME"
>backup</TT
>, showing a progress report while running:
</P><PRE
CLASS="SCREEN"
><SAMP
CLASS="PROMPT"
>$</SAMP
> <KBD
CLASS="USERINPUT"
>pg_basebackup -D backup -Ft -z -P</KBD
></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"
><SAMP
CLASS="PROMPT"
>$</SAMP
> <KBD
CLASS="USERINPUT"
>pg_basebackup -D - -Ft | bzip2 > backup.tar.bz2</KBD
></PRE
><P>
(This command will fail if there are multiple tablespaces in the
database.)
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN81946"
></A
><H2
>See Also</H2
><A
HREF="app-pgdump.html"
>pg_dump</A
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