| | pg_dumpNamepg_dump -- extract an EnterpriseDB database into a script file or other archive file
Synopsispg_dump [option...] [dbname] Description
pg_dump is a utility for backing up an
EnterpriseDB 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. The script
files are in plain-text format and contain the SQL commands required
to reconstruct the database to the state it was in at the time it was
saved. To restore these scripts, use edb-psql. They
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 that are meant to be used with
pg_restore to rebuild the database, and they also
allow pg_restore to be selective about
what is restored, or even to reorder the items prior to being
restored. The archive files are also 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. The tar format
(-Ft) is not compressed and it is not possible to
reorder data when loading, but it is otherwise quite flexible;
moreover, it can be manipulated with other tools such as
tar.
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 are used to control the output format.
- 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 object definitions (schema)
This option is only meaningful for the plain-text format. For
the other formats, you may specify the option when you
call pg_restore.
- -b
--blobs Include large objects in dump.
- -c
--clean Output commands to clean (drop)
database objects prior to (the commands for) creating them.
This option is only meaningful for the plain-text format. For
the other formats, you may 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 you connect
to before running the script.)
This option is only meaningful for the plain-text format. For
the other formats, you may specify the option when you
call pg_restore.
- -d
--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-EnterpriseDB databases. Note that
the restore may fail altogether if you have rearranged column order.
The -D option is safer, though even slower.
- -D
--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-EnterpriseDB databases.
- -f file
--file=file Send output to the specified file. If this is omitted, the
standard output is used.
- -F format
--format=format Selects the format of the output.
format can be one of the following:
- p
Output a plain-text SQL script file (default)
- t
Output a tar archive suitable for input into
pg_restore. Using this archive format
allows reordering and/or exclusion of database objects
at the time the database is restored. It is also possible to limit
which data is reloaded at restore time.
- c
Output a custom archive suitable for input into
pg_restore. This is the most flexible
format in that it allows reordering of loading data as well
as object definitions. This format is also compressed by default.
- -i
--ignore-version Ignore version mismatch between
pg_dump and the database server.
- -n namespace
--schema=schema Dump the contents of schema
only. If this option is not specified, all non-system schemas
in the target database will be dumped.
Note: In this mode, pg_dump makes no
attempt to dump any other database objects that objects in the
selected schema may depend upon. Therefore, there is no
guarantee that the results of a single-schema dump can be
successfully restored by themselves into a clean database.
- -o
--oids Dump object identifiers (OIDs) 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
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 other formats, you may 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.
- -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 data for table
only. It is possible for there to be
multiple tables with the same name in different schemas; if that
is the case, all matching tables will be dumped. Specify both
--schema and --table to select just one table.
Note: In this mode, pg_dump makes no
attempt to dump any other database objects that the selected table
may depend upon. Therefore, there is no guarantee
that the results of a single-table dump can be successfully
restored by themselves into a clean database.
- -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.
- -x
--no-privileges
--no-acl Prevent dumping of access privileges (grant/revoke commands).
- -X disable-dollar-quoting
--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.
- -X disable-triggers
--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 other formats, you may specify the option when you
call pg_restore.
- -X use-set-session-authorization
--use-set-session-authorization Output SQL standard SET SESSION AUTHORIZATION commands instead
of OWNER TO commands. This makes the dump more standards compatible,
but depending on the history of the objects in the dump, may not
restore properly.
- -Z 0..9
--compress=0..9 Specify the compression level to use in archive formats that
support compression. (Currently only the custom archive
format supports compression.)
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
Connect as the given user
- -W
Force a password prompt. This should happen automatically if
the server requires password authentication.
Environment- PGDATABASE
PGHOST
PGPORT
PGUSER Default connection parameters.
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, edb-psql.
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;
pg_dump has a few limitations:
When dumping a single table or as plain text, pg_dump
does not handle large objects. Large objects must be dumped with the
entire database using one of the non-text archive formats.
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 commands
to re-enable them after the data has been inserted. If the
restore is stopped in the middle, the system catalogs may 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 a 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 good performance.
Examples To dump a database:
$ pg_dump mydb > db.out
To reload this database:
$ psql -d database -f db.out
To dump a database called mydb that contains
large objects to a tar file:
$ pg_dump -Ft -b mydb > db.tar
To reload this database (with large objects) to an
existing database called newdb:
$ pg_restore -d newdb db.tar
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