1PG_BASEBACKUP(1) PostgreSQL 9.2.24 Documentation PG_BASEBACKUP(1)
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6 pg_basebackup - take a base backup of a PostgreSQL cluster
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9 pg_basebackup [option...]
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12 pg_basebackup is used to take base backups of a running PostgreSQL
13 database cluster. These are taken without affecting other clients to
14 the database, and can be used both for point-in-time recovery (see
15 Section 24.3, “Continuous Archiving and Point-in-Time Recovery (PITR)”,
16 in the documentation) and as the starting point for a log shipping or
17 streaming replication standby servers (see Section 25.2, “Log-Shipping
18 Standby Servers”, in the documentation).
19 pg_basebackup makes a binary copy of the database cluster files, while
21 making sure the system is put in and out of backup mode automatically.
22 Backups are always taken of the entire database cluster; it is not
23 possible to back up individual databases or database objects. For
24 individual database backups, a tool such as pg_dump(1) must be used.
25 The backup is made over a regular PostgreSQL connection, and uses the
27 replication protocol. The connection must be made with a superuser or a
28 user having REPLICATION permissions (see Section 20.2, “Role
29 Attributes”, in the documentation), and pg_hba.conf must explicitly
30 permit the replication connection. The server must also be configured
31 with max_wal_senders set high enough to leave at least one session
32 available for the backup.
33 There can be multiple pg_basebackups running at the same time, but it
35 is better from a performance point of view to take only one backup, and
36 copy the result.
37 pg_basebackup can make a base backup from not only the master but also
39 the standby. To take a backup from the standby, set up the standby so
40 that it can accept replication connections (that is, set
41 max_wal_senders and hot_standby, and configure host-based
42 authentication). You will also need to enable full_page_writes on the
43 master.
44 Note that there are some limitations in an online backup from the
46 standby:
47 · The backup history file is not created in the database cluster
49 backed up.
50 · There is no guarantee that all WAL files required for the backup
52 are archived at the end of backup. If you are planning to use the
53 backup for an archive recovery and want to ensure that all required
54 files are available at that moment, you need to include them into
55 the backup by using the -x option.
56 · If the standby is promoted to the master during online backup, the
58 backup fails.
59 · All WAL records required for the backup must contain sufficient
61 full-page writes, which requires you to enable full_page_writes on
62 the master and not to use a tool like pg_compresslog as
63 archive_command to remove full-page writes from WAL files.
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67 The following command-line options control the location and format of
68 the output.
69 -D directory, --pgdata=directory
71 Directory to write the output to. pg_basebackup will create the
72 directory and any parent directories if necessary. The directory
73 may already exist, but it is an error if the directory already
74 exists and is not empty.
75 When the backup is in tar mode, and the directory is specified as -
77 (dash), the tar file will be written to stdout.
78 This option is required.
80 -F format, --format=format
82 Selects the format for the output. format can be one of the
83 following:
84 p, plain
86 Write the output as plain files, with the same layout as the
87 current data directory and tablespaces. When the cluster has no
88 additional tablespaces, the whole database will be placed in
89 the target directory. If the cluster contains additional
90 tablespaces, the main data directory will be placed in the
91 target directory, but all other tablespaces will be placed in
92 the same absolute path as they have on the server.
93 This is the default format.
95 t, tar
97 Write the output as tar files in the target directory. The main
98 data directory will be written to a file named base.tar, and
99 all other tablespaces will be named after the tablespace OID.
100 If the value - (dash) is specified as target directory, the tar
102 contents will be written to standard output, suitable for
103 piping to for example gzip. This is only possible if the
104 cluster has no additional tablespaces.
105 -x, --xlog
107 Using this option is equivalent of using -X with method fetch.
108 -X method, --xlog-method=method
110 Includes the required transaction log files (WAL files) in the
111 backup. This will include all transaction logs generated during the
112 backup. If this option is specified, it is possible to start a
113 postmaster directly in the extracted directory without the need to
114 consult the log archive, thus making this a completely standalone
115 backup.
116 The following methods for collecting the transaction logs are
118 supported:
119 f, fetch
121 The transaction log files are collected at the end of the
122 backup. Therefore, it is necessary for the wal_keep_segments
123 parameter to be set high enough that the log is not removed
124 before the end of the backup. If the log has been rotated when
125 it's time to transfer it, the backup will fail and be unusable.
126 s, stream
128 Stream the transaction log while the backup is created. This
129 will open a second connection to the server and start streaming
130 the transaction log in parallel while running the backup.
131 Therefore, it will use up two slots configured by the
132 max_wal_senders parameter. As long as the client can keep up
133 with transaction log received, using this mode requires no
134 extra transaction logs to be saved on the master.
135 -z, --gzip
138 Enables gzip compression of tar file output, with the default
139 compression level. Compression is only available when using the tar
140 format.
141 -Z level, --compress=level
143 Enables gzip compression of tar file output, and specifies the
144 compression level (0 through 9, 0 being no compression and 9 being
145 best compression). Compression is only available when using the tar
146 format.
147 The following command-line options control the generation of the backup
149 and the running of the program.
150 -c fast|spread, --checkpoint=fast|spread
152 Sets checkpoint mode to fast or spread (default).
153 -l label, --label=label
155 Sets the label for the backup. If none is specified, a default
156 value of “pg_basebackup base backup” will be used.
157 -P, --progress
159 Enables progress reporting. Turning this on will deliver an
160 approximate progress report during the backup. Since the database
161 may change during the backup, this is only an approximation and may
162 not end at exactly 100%. In particular, when WAL log is included in
163 the backup, the total amount of data cannot be estimated in
164 advance, and in this case the estimated target size will increase
165 once it passes the total estimate without WAL.
166 When this is enabled, the backup will start by enumerating the size
168 of the entire database, and then go back and send the actual
169 contents. This may make the backup take slightly longer, and in
170 particular it will take longer before the first data is sent.
171 -v, --verbose
173 Enables verbose mode. Will output some extra steps during startup
174 and shutdown, as well as show the exact file name that is currently
175 being processed if progress reporting is also enabled.
176 The following command-line options control the database connection
178 parameters.
179 -h host, --host=host
181 Specifies the host name of the machine on which the server is
182 running. If the value begins with a slash, it is used as the
183 directory for the Unix domain socket. The default is taken from the
184 PGHOST environment variable, if set, else a Unix domain socket
185 connection is attempted.
186 -p port, --port=port
188 Specifies the TCP port or local Unix domain socket file extension
189 on which the server is listening for connections. Defaults to the
190 PGPORT environment variable, if set, or a compiled-in default.
191 -s interval, --status-interval=interval
193 Specifies the number of seconds between status packets sent back to
194 the server. This is required when streaming the transaction log
195 (using --xlog=stream) if replication timeout is configured on the
196 server, and allows for easier monitoring. A value of zero disables
197 the status updates completely. The default value is 10 seconds.
198 -U username, --username=username
200 User name to connect as.
201 -w, --no-password
203 Never issue a password prompt. If the server requires password
204 authentication and a password is not available by other means such
205 as a .pgpass file, the connection attempt will fail. This option
206 can be useful in batch jobs and scripts where no user is present to
207 enter a password.
208 -W, --password
210 Force pg_basebackup to prompt for a password before connecting to a
211 database.
212 This option is never essential, since pg_basebackup will
214 automatically prompt for a password if the server demands password
215 authentication. However, pg_basebackup will waste a connection
216 attempt finding out that the server wants a password. In some cases
217 it is worth typing -W to avoid the extra connection attempt.
218 Other options are also available:
220 -V, --version
222 Print the pg_basebackup version and exit.
223 -?, --help
225 Show help about pg_basebackup command line arguments, and exit.
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228 This utility, like most other PostgreSQL utilities, uses the
229 environment variables supported by libpq (see Section 31.14,
230 “Environment Variables”, in the documentation).
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233 The backup will include all files in the data directory and
234 tablespaces, including the configuration files and any additional files
235 placed in the directory by third parties. Only regular files and
236 directories are allowed in the data directory, no symbolic links or
237 special device files.
238 The way PostgreSQL manages tablespaces, the path for all additional
240 tablespaces must be identical whenever a backup is restored. The main
241 data directory, however, is relocatable to any location.
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244 To create a base backup of the server at mydbserver and store it in the
245 local directory /usr/local/pgsql/data:
246 $ pg_basebackup -h mydbserver -D /usr/local/pgsql/data
248 To create a backup of the local server with one compressed tar file for
250 each tablespace, and store it in the directory backup, showing a
251 progress report while running:
252 $ pg_basebackup -D backup -Ft -z -P
254 To create a backup of a single-tablespace local database and compress
256 this with bzip2:
257 $ pg_basebackup -D - -Ft | bzip2 > backup.tar.bz2
259 (This command will fail if there are multiple tablespaces in the
261 database.)
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264 pg_dump(1)
265PostgreSQL 9.2.24 2017-11-06 PG_BASEBACKUP(1)