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).

pg_dump only dumps a single database. To back up an entire cluster, or to back up global objects that are common to all databases in a cluster (such as roles and tablespaces), use pg_dumpall(1).

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 formats are the “custom” format (-Fc) and the “directory” format (-Fd). They allow for selection and reordering of all archived items, support parallel restoration, and are compressed by default. The “directory” format is the only format that supports parallel dumps.

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

-a
--data-only

-b
--blobs

-B
--no-blobs

-c
--clean

-C
--create

-e pattern
--extension=pattern

-E encoding
--encoding=encoding

-f file
--file=file

-F format
--format=format

-j njobs
--jobs=njobs

-n pattern
--schema=pattern

-N pattern
--exclude-schema=pattern

-O
--no-owner

-R
--no-reconnect

-s
--schema-only

-S username
--superuser=username

-t pattern
--table=pattern

-T pattern
--exclude-table=pattern

-v
--verbose

-V
--version

-x
--no-privileges
--no-acl

-Z 0..9
--compress=0..9

--binary-upgrade

--column-inserts
--attribute-inserts

--disable-dollar-quoting

--disable-triggers

--enable-row-security

--exclude-table-data=pattern

--extra-float-digits=ndigits

--if-exists

--include-foreign-data=foreignserver

--inserts

--load-via-partition-root

--lock-wait-timeout=timeout

--no-comments

--no-publications

--no-security-labels

--no-subscriptions

--no-sync

--no-table-access-method

--no-tablespaces

--no-toast-compression

--no-unlogged-table-data

--on-conflict-do-nothing

--quote-all-identifiers

--rows-per-insert=nrows

--section=sectionname

--serializable-deferrable

--snapshot=snapshotname

--strict-names

--use-set-session-authorization

-?
--help

The following command-line options control the database connection parameters.

-d dbname
--dbname=dbname

-h host
--host=host

-p port
--port=port

-U username
--username=username

-w
--no-password

-W
--password

--role=rolename

ENVIRONMENT¶

PGDATABASE
PGHOST
PGOPTIONS
PGPORT
PGUSER

PG_COLOR

This utility, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Section 34.15).

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 cumulative statistics system. 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.

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 25.1.3 and Section 25.1.6 for more information.

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 9.2 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 version — not 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. Use of the --quote-all-identifiers option is recommended in cross-version cases, as it can prevent problems arising from varying reserved-word lists in different PostgreSQL versions.

When dumping logical replication subscriptions, pg_dump will generate CREATE SUBSCRIPTION commands that use the connect = false option, so that restoring the subscription does not make remote connections for creating a replication slot or for initial table copy. That way, the dump can be restored without requiring network access to the remote servers. It is then up to the user to reactivate the subscriptions in a suitable way. If the involved hosts have changed, the connection information might have to be changed. It might also be appropriate to truncate the target tables before initiating a new full table copy. If users intend to copy initial data during refresh they must create the slot with two_phase = false. After the initial sync, the two_phase option will be automatically enabled by the subscriber if the subscription had been originally created with two_phase = true option.

EXAMPLES¶

To dump a database called mydb into an 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 dump a database into a directory-format archive in parallel with 5 worker jobs:

$ pg_dump -Fd mydb -j 5 -f dumpdir

To reload an archive file into a (freshly created) database named newdb:

$ pg_restore -d newdb db.dump

To reload an archive file into the same database it was dumped from, discarding the current contents of that database:

$ pg_restore -d postgres --clean --create 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 below). 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)