Provided by: postgres-xc-client_1.1-2ubuntu2_amd64 
NAME
pg_dump - extract a PostgreSQL database into a script file or other archive file
SYNOPSIS
pg_dump [connection-option...] [option...] [dbname]
DESCRIPTION
pg_dump is a utility for backing up a PostgreSQL database. It makes consistent backups even if the
database is being used concurrently. pg_dump does not block other users accessing the database (readers
or writers).
Dumps can be output in script or archive file formats. Script dumps are plain-text files containing the
SQL commands required to reconstruct the database to the state it was in at the time it was saved. To
restore from such a script, feed it to psql(1). Script files can be used to reconstruct the database even
on other machines and other architectures; with some modifications, even on other SQL database products.
The alternative archive file formats must be used with pg_restore(1) to rebuild the database. They allow
pg_restore to be selective about what is restored, or even to reorder the items prior to being restored.
The archive file formats are designed to be portable across architectures.
When used with one of the archive file formats and combined with pg_restore, pg_dump provides a flexible
archival and transfer mechanism. pg_dump can be used to backup an entire database, then pg_restore can
be used to examine the archive and/or select which parts of the database are to be restored. The most
flexible output file format is the “custom” format (-Fc). It allows for selection and reordering of all
archived items, and is compressed by default.
While running pg_dump, one should examine the output for any warnings (printed on standard error),
especially in light of the limitations listed below.
OPTIONS
The following command-line options control the content and format of the output.
dbname
Specifies the name of the database to be dumped. If this is not specified, the environment variable
PGDATABASE is used. If that is not set, the user name specified for the connection is used.
-a, --data-only
Dump only the data, not the schema (data definitions). Table data, large objects, and sequence values
are dumped.
This option is similar to, but for historical reasons not identical to, specifying --section=data.
-b, --blobs
Include large objects in the dump. This is the default behavior except when --schema, --table, or
--schema-only is specified, so the -b switch is only useful to add large objects to selective dumps.
-c, --clean
Output commands to clean (drop) database objects prior to outputting the commands for creating them.
(Restore might generate some harmless error messages, if any objects were not present in the
destination database.)
This option is only meaningful for the plain-text format. For the archive formats, you can specify
the option when you call pg_restore.
-C, --create
Begin the output with a command to create the database itself and reconnect to the created database.
(With a script of this form, it doesn't matter which database in the destination installation you
connect to before running the script.) If --clean is also specified, the script drops and recreates
the target database before reconnecting to it.
This option is only meaningful for the plain-text format. For the archive formats, you can specify
the option when you call pg_restore.
-E encoding, --encoding=encoding
Create the dump in the specified character set encoding. By default, the dump is created in the
database encoding. (Another way to get the same result is to set the PGCLIENTENCODING environment
variable to the desired dump encoding.)
-f file, --file=file
Send output to the specified file. This parameter can be omitted for file based output formats, in
which case the standard output is used. It must be given for the directory output format however,
where it specifies the target directory instead of a file. In this case the directory is created by
pg_dump and must not exist before.
-F format, --format=format
Selects the format of the output. format can be one of the following:
p, plain
Output a plain-text SQL script file (the default).
c, custom
Output a custom-format archive suitable for input into pg_restore. Together with the directory
output format, this is the most flexible output format in that it allows manual selection and
reordering of archived items during restore. This format is also compressed by default.
d, directory
Output a directory-format archive suitable for input into pg_restore. This will create a
directory with one file for each table and blob being dumped, plus a so-called Table of Contents
file describing the dumped objects in a machine-readable format that pg_restore can read. A
directory format archive can be manipulated with standard Unix tools; for example, files in an
uncompressed archive can be compressed with the gzip tool. This format is compressed by default.
t, tar
Output a tar-format archive suitable for input into pg_restore. The tar-format is compatible with
the directory-format; extracting a tar-format archive produces a valid directory-format archive.
However, the tar-format does not support compression and has a limit of 8 GB on the size of
individual tables. Also, the relative order of table data items cannot be changed during restore.
-i, --ignore-version
A deprecated option that is now ignored.
-n schema, --schema=schema
Dump only schemas matching schema; this selects both the schema itself, and all its contained
objects. When this option is not specified, all non-system schemas in the target database will be
dumped. Multiple schemas can be selected by writing multiple -n switches. Also, the schema parameter
is interpreted as a pattern according to the same rules used by psql's \d commands (see Patterns), so
multiple schemas can also be selected by writing wildcard characters in the pattern. When using
wildcards, be careful to quote the pattern if needed to prevent the shell from expanding the
wildcards; see EXAMPLES.
Note
When -n is specified, pg_dump makes no attempt to dump any other database objects that the
selected schema(s) might depend upon. Therefore, there is no guarantee that the results of a
specific-schema dump can be successfully restored by themselves into a clean database.
Note
Non-schema objects such as blobs are not dumped when -n is specified. You can add blobs back to
the dump with the --blobs switch.
-N schema, --exclude-schema=schema
Do not dump any schemas matching the schema pattern. The pattern is interpreted according to the same
rules as for -n. -N can be given more than once to exclude schemas matching any of several patterns.
When both -n and -N are given, the behavior is to dump just the schemas that match at least one -n
switch but no -N switches. If -N appears without -n, then schemas matching -N are excluded from what
is otherwise a normal dump.
-o, --oids
Dump object identifiers (OIDs) as part of the data for every table. Use this option if your
application references the OID columns in some way (e.g., in a foreign key constraint). Otherwise,
this option should not be used.
-O, --no-owner
Do not output commands to set ownership of objects to match the original database. By default,
pg_dump issues ALTER OWNER or SET SESSION AUTHORIZATION statements to set ownership of created
database objects. These statements will fail when the script is run unless it is started by a
superuser (or the same user that owns all of the objects in the script). To make a script that can be
restored by any user, but will give that user ownership of all the objects, specify -O.
This option is only meaningful for the plain-text format. For the archive formats, you can specify
the option when you call pg_restore.
-R, --no-reconnect
This option is obsolete but still accepted for backwards compatibility.
-s, --schema-only
Dump only the object definitions (schema), not data.
This option is the inverse of --data-only. It is similar to, but for historical reasons not identical
to, specifying --section=pre-data --section=post-data.
(Do not confuse this with the --schema option, which uses the word “schema” in a different meaning.)
To exclude table data for only a subset of tables in the database, see --exclude-table-data.
-S username, --superuser=username
Specify the superuser user name to use when disabling triggers. This is only relevant if
--disable-triggers is used. (Usually, it's better to leave this out, and instead start the resulting
script as superuser.)
-t table, --table=table
Dump only tables (or views or sequences or foreign tables) matching table. Multiple tables can be
selected by writing multiple -t switches. Also, the table parameter is interpreted as a pattern
according to the same rules used by psql's \d commands (see Patterns), so multiple tables can also be
selected by writing wildcard characters in the pattern. When using wildcards, be careful to quote the
pattern if needed to prevent the shell from expanding the wildcards; see EXAMPLES.
The -n and -N switches have no effect when -t is used, because tables selected by -t will be dumped
regardless of those switches, and non-table objects will not be dumped.
Note
When -t is specified, pg_dump makes no attempt to dump any other database objects that the
selected table(s) might depend upon. Therefore, there is no guarantee that the results of a
specific-table dump can be successfully restored by themselves into a clean database.
Note
The behavior of the -t switch is not entirely upward compatible with pre-8.2 PostgreSQL versions.
Formerly, writing -t tab would dump all tables named tab, but now it just dumps whichever one is
visible in your default search path. To get the old behavior you can write -t '*.tab'. Also, you
must write something like -t sch.tab to select a table in a particular schema, rather than the
old locution of -n sch -t tab.
-T table, --exclude-table=table
Do not dump any tables matching the table pattern. The pattern is interpreted according to the same
rules as for -t. -T can be given more than once to exclude tables matching any of several patterns.
When both -t and -T are given, the behavior is to dump just the tables that match at least one -t
switch but no -T switches. If -T appears without -t, then tables matching -T are excluded from what
is otherwise a normal dump.
-v, --verbose
Specifies verbose mode. This will cause pg_dump to output detailed object comments and start/stop
times to the dump file, and progress messages to standard error.
-V, --version
Print the pg_dump version and exit.
-x, --no-privileges, --no-acl
Prevent dumping of access privileges (grant/revoke commands).
-Z 0..9, --compress=0..9
Specify the compression level to use. Zero means no compression. For the custom archive format, this
specifies compression of individual table-data segments, and the default is to compress at a moderate
level. For plain text output, setting a nonzero compression level causes the entire output file to be
compressed, as though it had been fed through gzip; but the default is not to compress. The tar
archive format currently does not support compression at all.
--binary-upgrade
This option is for use by in-place upgrade utilities. Its use for other purposes is not recommended
or supported. The behavior of the option may change in future releases without notice.
--column-inserts, --attribute-inserts
Dump data as INSERT commands with explicit column names (INSERT INTO table (column, ...) VALUES ...).
This will make restoration very slow; it is mainly useful for making dumps that can be loaded into
non-PostgreSQL databases. However, since this option generates a separate command for each row, an
error in reloading a row causes only that row to be lost rather than the entire table contents.
--disable-dollar-quoting
This option disables the use of dollar quoting for function bodies, and forces them to be quoted
using SQL standard string syntax.
--disable-triggers
This option is only relevant when creating a data-only dump. It instructs pg_dump to include commands
to temporarily disable triggers on the target tables while the data is reloaded. Use this if you have
referential integrity checks or other triggers on the tables that you do not want to invoke during
data reload.
Presently, the commands emitted for --disable-triggers must be done as superuser. So, you should also
specify a superuser name with -S, or preferably be careful to start the resulting script as a
superuser.
This option is only meaningful for the plain-text format. For the archive formats, you can specify
the option when you call pg_restore.
--exclude-table-data=table
Do not dump data for any tables matching the table pattern. The pattern is interpreted according to
the same rules as for -t. --exclude-table-data can be given more than once to exclude tables
matching any of several patterns. This option is useful when you need the definition of a particular
table even though you do not need the data in it.
To exclude data for all tables in the database, see --schema-only.
--inserts
Dump data as INSERT commands (rather than COPY). This will make restoration very slow; it is mainly
useful for making dumps that can be loaded into non-PostgreSQL databases. However, since this option
generates a separate command for each row, an error in reloading a row causes only that row to be
lost rather than the entire table contents. Note that the restore might fail altogether if you have
rearranged column order. The --column-inserts option is safe against column order changes, though
even slower.
--lock-wait-timeout=timeout
Do not wait forever to acquire shared table locks at the beginning of the dump. Instead fail if
unable to lock a table within the specified timeout. The timeout may be specified in any of the
formats accepted by SET statement_timeout. (Allowed values vary depending on the server version you
are dumping from, but an integer number of milliseconds is accepted by all versions since 7.3. This
option is ignored when dumping from a pre-7.3 server.)
--no-security-labels
Do not dump security labels.
--no-tablespaces
Do not output commands to select tablespaces. With this option, all objects will be created in
whichever tablespace is the default during restore.
This option is only meaningful for the plain-text format. For the archive formats, you can specify
the option when you call pg_restore.
--no-unlogged-table-data
Do not dump the contents of unlogged tables. This option has no effect on whether or not the table
definitions (schema) are dumped; it only suppresses dumping the table data. Data in unlogged tables
is always excluded when dumping from a standby server.
--quote-all-identifiers
Force quoting of all identifiers. This may be useful when dumping a database for migration to a
future version that may have introduced additional keywords.
--section=sectionname
Only dump the named section. The section name can be pre-data, data, or post-data. This option can be
specified more than once to select multiple sections. The default is to dump all sections.
The data section contains actual table data, large-object contents, and sequence values. Post-data
items include definitions of indexes, triggers, rules, and constraints other than validated check
constraints. Pre-data items include all other data definition items.
--serializable-deferrable
Use a serializable transaction for the dump, to ensure that the snapshot used is consistent with
later database states; but do this by waiting for a point in the transaction stream at which no
anomalies can be present, so that there isn't a risk of the dump failing or causing other
transactions to roll back with a serialization_failure. See Chapter 13, Concurrency Control, in the
documentation for more information about transaction isolation and concurrency control.
This option is not beneficial for a dump which is intended only for disaster recovery. It could be
useful for a dump used to load a copy of the database for reporting or other read-only load sharing
while the original database continues to be updated. Without it the dump may reflect a state which is
not consistent with any serial execution of the transactions eventually committed. For example, if
batch processing techniques are used, a batch may show as closed in the dump without all of the items
which are in the batch appearing.
This option will make no difference if there are no read-write transactions active when pg_dump is
started. If read-write transactions are active, the start of the dump may be delayed for an
indeterminate length of time. Once running, performance with or without the switch is the same.
--use-set-session-authorization
Output SQL-standard SET SESSION AUTHORIZATION commands instead of ALTER OWNER commands to determine
object ownership. This makes the dump more standards-compatible, but depending on the history of the
objects in the dump, might not restore properly. Also, a dump using SET SESSION AUTHORIZATION will
certainly require superuser privileges to restore correctly, whereas ALTER OWNER requires lesser
privileges.
--dump-nodes
Note
The following description applies only to Postgres-XC
Output commands to create nodes and node groups. This option may be used while adding a new
coordinator to an existing Postgres-XC cluster.
-?, --help
Show help about pg_dump command line arguments, and exit.
The following command-line options control the database connection parameters.
-h host, --host=host
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 PGHOST
environment variable, if set, else a Unix domain socket connection is attempted.
-p port, --port=port
Specifies the TCP port or local Unix domain socket file extension on which the server is listening
for connections. Defaults to the PGPORT environment variable, if set, or a compiled-in default.
-U username, --username=username
User name to connect as.
-w, --no-password
Never issue a password prompt. If the server requires password authentication and a password is not
available by other means such as a .pgpass 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.
-W, --password
Force pg_dump to prompt for a password before connecting to a database.
This option is never essential, since pg_dump will automatically prompt for a password if the server
demands password authentication. However, pg_dump will waste a connection attempt finding out that
the server wants a password. In some cases it is worth typing -W to avoid the extra connection
attempt.
--role=rolename
Specifies a role name to be used to create the dump. This option causes pg_dump to issue a SET
ROLErolename command after connecting to the database. It is useful when the authenticated user
(specified by -U) lacks privileges needed by pg_dump, but can switch to a role with the required
rights. Some installations have a policy against logging in directly as a superuser, and use of this
option allows dumps to be made without violating the policy.
ENVIRONMENT
PGDATABASE, PGHOST, PGOPTIONS, PGPORT, PGUSER
Default connection parameters.
This utility, like most other PostgreSQL utilities, also uses the environment variables supported by
libpq (see Section 32.14, “Environment Variables”, in the documentation).
DIAGNOSTICS
pg_dump internally executes SELECT statements. If you have problems running pg_dump, make sure you are
able to select information from the database using, for example, psql(1). Also, any default connection
settings and environment variables used by the libpq front-end library will apply.
The database activity of pg_dump is normally collected by the statistics collector. If this is
undesirable, you can set parameter track_counts to false via PGOPTIONS or the ALTER USER command.
NOTES
If your database cluster has any local additions to the template1 database, be careful to restore the
output of pg_dump into a truly empty database; otherwise you are likely to get errors due to duplicate
definitions of the added objects. To make an empty database without any local additions, copy from
template0 not template1, for example:
CREATE DATABASE foo WITH TEMPLATE template0;
When a data-only dump is chosen and the option --disable-triggers is used, pg_dump emits commands to
disable triggers on user tables before inserting the data, and then commands to re-enable them after the
data has been inserted. If the restore is stopped in the middle, the system catalogs might be left in the
wrong state.
Members of tar archives are limited to a size less than 8 GB. (This is an inherent limitation of the tar
file format.) Therefore this format cannot be used if the textual representation of any one table exceeds
that size. The total size of a tar archive and any of the other output formats is not limited, except
possibly by the operating system.
The dump file produced by pg_dump does not contain the statistics used by the optimizer to make query
planning decisions. Therefore, it is wise to run ANALYZE after restoring from a dump file to ensure
optimal performance; see Section 22.1.3, “Updating Planner Statistics”, in the documentation and Section
22.1.6, “The Autovacuum Daemon”, in the documentation for more information. The dump file also does not
contain any ALTER DATABASE ... SET commands; these settings are dumped by pg_dumpall(1), along with
database users and other installation-wide settings.
Because pg_dump is used to transfer data to newer versions of PostgreSQL, the output of pg_dump can be
expected to load into PostgreSQL server versions newer than pg_dump's version. pg_dump can also dump
from PostgreSQL servers older than its own version. (Currently, servers back to version 7.0 are
supported.) However, pg_dump cannot dump from PostgreSQL servers newer than its own major version; it
will refuse to even try, rather than risk making an invalid dump. Also, it is not guaranteed that
pg_dump's output can be loaded into a server of an older major versionnot even if the dump was taken from
a server of that version. Loading a dump file into an older server may require manual editing of the dump
file to remove syntax not understood by the older server.
EXAMPLES
To dump a database called mydb into a SQL-script file:
$ pg_dump mydb > db.sql
To reload such a script into a (freshly created) database named newdb:
$ psql -d newdb -f db.sql
To dump a database into a custom-format archive file:
$ pg_dump -Fc mydb > db.dump
To dump a database into a directory-format archive:
$ pg_dump -Fd mydb -f dumpdir
To reload an archive file into a (freshly created) database named newdb:
$ pg_restore -d newdb db.dump
To dump a single table named mytab:
$ pg_dump -t mytab mydb > db.sql
To dump all tables whose names start with emp in the detroit schema, except for the table named
employee_log:
$ pg_dump -t 'detroit.emp*' -T detroit.employee_log mydb > db.sql
To dump all schemas whose names start with east or west and end in gsm, excluding any schemas whose names
contain the word test:
$ pg_dump -n 'east*gsm' -n 'west*gsm' -N '*test*' mydb > db.sql
The same, using regular expression notation to consolidate the switches:
$ pg_dump -n '(east|west)*gsm' -N '*test*' mydb > db.sql
To dump all database objects except for tables whose names begin with ts_:
$ pg_dump -T 'ts_*' mydb > db.sql
To specify an upper-case or mixed-case name in -t and related switches, you need to double-quote the
name; else it will be folded to lower case (see Patterns). But double quotes are special to the shell, so
in turn they must be quoted. Thus, to dump a single table with a mixed-case name, you need something like
$ pg_dump -t '"MixedCaseName"' mydb > mytab.sql
SEE ALSO
pg_dumpall(1), pg_restore(1), psql(1)
Postgres-XC 1.1 2014-04-07 PG_DUMP(1)