pg_restore - Online in the Cloud

PROGRAM:

NAME

pg_restore - restore a PostgreSQL database from an archive file created by pg_dump

SYNOPSIS

pg_restore [connection-option...] [option...] [filename]

DESCRIPTION

pg_restore is a utility for restoring a PostgreSQL database from an archive created by
pg_dump(1) in one of the non-plain-text formats. It will issue the commands necessary to
reconstruct the database to the state it was in at the time it was saved. The archive
files 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 designed to be portable across
architectures.

pg_restore can operate in two modes. If a database name is specified, pg_restore connects
to that database and restores archive contents directly into the database. Otherwise, a
script containing the SQL commands necessary to rebuild the database is created and
written to a file or standard output. This script output is equivalent to the plain text
output format of pg_dump. Some of the options controlling the output are therefore
analogous to pg_dump options.

Obviously, pg_restore cannot restore information that is not present in the archive file.
For instance, if the archive was made using the “dump data as INSERT commands” option,
pg_restore will not be able to load the data using COPY statements.

OPTIONS

pg_restore accepts the following command line arguments.

filename
Specifies the location of the archive file (or directory, for a directory-format
archive) to be restored. If not specified, the standard input is used.

-a
--data-only
Restore only the data, not the schema (data definitions). Table data, large objects,
and sequence values are restored, if present in the archive.

This option is similar to, but for historical reasons not identical to, specifying
--section=data.

-c
--clean
Clean (drop) database objects before recreating them. (Unless --if-exists is used,
this might generate some harmless error messages, if any objects were not present in
the destination database.)

-C
--create
Create the database before restoring into it. If --clean is also specified, drop and
recreate the target database before connecting to it.

When this option is used, the database named with -d is used only to issue the initial
DROP DATABASE and CREATE DATABASE commands. All data is restored into the database
name that appears in the archive.

-d dbname
--dbname=dbname
Connect to database dbname and restore directly into the database.

-e
--exit-on-error
Exit if an error is encountered while sending SQL commands to the database. The
default is to continue and to display a count of errors at the end of the restoration.

-f filename
--file=filename
Specify output file for generated script, or for the listing when used with -l.
Default is the standard output.

-F format
--format=format
Specify format of the archive. It is not necessary to specify the format, since
pg_restore will determine the format automatically. If specified, it can be one of the
following:

c
custom
The archive is in the custom format of pg_dump.

d
directory
The archive is a directory archive.

t
tar
The archive is a tar archive.

-I index
--index=index
Restore definition of named index only. Multiple indexes may be specified with
multiple -I switches.

-j number-of-jobs
--jobs=number-of-jobs
Run the most time-consuming parts of pg_restore — those which load data, create
indexes, or create constraints — using multiple concurrent jobs. This option can
dramatically reduce the time to restore a large database to a server running on a
multiprocessor machine.

Each job is one process or one thread, depending on the operating system, and uses a
separate connection to the server.

The optimal value for this option depends on the hardware setup of the server, of the
client, and of the network. Factors include the number of CPU cores and the disk
setup. A good place to start is the number of CPU cores on the server, but values
larger than that can also lead to faster restore times in many cases. Of course,
values that are too high will lead to decreased performance because of thrashing.

Only the custom and directory archive formats are supported with this option. The
input must be a regular file or directory (not, for example, a pipe). This option is
ignored when emitting a script rather than connecting directly to a database server.
Also, multiple jobs cannot be used together with the option --single-transaction.

-l
--list
List the contents of the archive. The output of this operation can be used as input to
the -L option. Note that if filtering switches such as -n or -t are used with -l, they
will restrict the items listed.

-L list-file
--use-list=list-file
Restore only those archive elements that are listed in list-file, and restore them in
the order they appear in the file. Note that if filtering switches such as -n or -t
are used with -L, they will further restrict the items restored.

list-file is normally created by editing the output of a previous -l operation. Lines
can be moved or removed, and can also be commented out by placing a semicolon (;) at
the start of the line. See below for examples.

-n namespace
--schema=schema
Restore only objects that are in the named schema. Multiple schemas may be specified
with multiple -n switches. This can be combined with the -t option to restore just a
specific table.

-O
--no-owner
Do not output commands to set ownership of objects to match the original database. By
default, pg_restore issues ALTER OWNER or SET SESSION AUTHORIZATION statements to set
ownership of created schema elements. These statements will fail unless the initial
connection to the database is made by a superuser (or the same user that owns all of
the objects in the script). With -O, any user name can be used for the initial
connection, and this user will own all the created objects.

-P function-name(argtype [, ...])
--function=function-name(argtype [, ...])
Restore the named function only. Be careful to spell the function name and arguments
exactly as they appear in the dump file's table of contents. Multiple functions may be
specified with multiple -P switches.

-R
--no-reconnect
This option is obsolete but still accepted for backwards compatibility.

-s
--schema-only
Restore only the schema (data definitions), not data, to the extent that schema
entries are present in the archive.

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.)

-S username
--superuser=username
Specify the superuser user name to use when disabling triggers. This is relevant only
if --disable-triggers is used.

-t table
--table=table
Restore definition and/or data of named table only. Multiple tables may be specified
with multiple -t switches. This can be combined with the -n option to specify a
schema.

-T trigger
--trigger=trigger
Restore named trigger only. Multiple triggers may be specified with multiple -T
switches.

-v
--verbose
Specifies verbose mode.

-V
--version
Print the pg_restore version and exit.

-x
--no-privileges
--no-acl
Prevent restoration of access privileges (grant/revoke commands).

-1
--single-transaction
Execute the restore as a single transaction (that is, wrap the emitted commands in
BEGIN/COMMIT). This ensures that either all the commands complete successfully, or no
changes are applied. This option implies --exit-on-error.

--disable-triggers
This option is relevant only when performing a data-only restore. It instructs
pg_restore to execute 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, run pg_restore as a
PostgreSQL superuser.

--enable-row-security
This option is relevant only when restoring the contents of a table which has row
security. By default, pg_restore will set row_security to off, to ensure that all data
is restored in to the table. If the user does not have sufficient privileges to bypass
row security, then an error is thrown. This parameter instructs pg_restore to set
row_security to on instead, allowing the user to attempt to restore the contents of
the table with row security enabled. This might still fail if the user does not have
the right to insert the rows from the dump into the table.

Note that this option currently also requires the dump be in INSERT format, as COPY TO
does not support row security.

--if-exists
Use conditional commands (i.e. add an IF EXISTS clause) when cleaning database
objects. This option is not valid unless --clean is also specified.

--no-data-for-failed-tables
By default, table data is restored even if the creation command for the table failed
(e.g., because it already exists). With this option, data for such a table is skipped.
This behavior is useful if the target database already contains the desired table
contents. For example, auxiliary tables for PostgreSQL extensions such as PostGIS
might already be loaded in the target database; specifying this option prevents
duplicate or obsolete data from being loaded into them.

This option is effective only when restoring directly into a database, not when
producing SQL script output.

--no-security-labels
Do not output commands to restore security labels, even if the archive contains them.

--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.

--section=sectionname
Only restore 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 restore all sections.

The data section contains actual table data as well as large-object definitions.
Post-data items consist of definitions of indexes, triggers, rules and constraints
other than validated check constraints. Pre-data items consist of all other data
definition items.

--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.

-?
--help
Show help about pg_restore command line arguments, and exit.

pg_restore also accepts the following command line arguments for 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_restore to prompt for a password before connecting to a database.

This option is never essential, since pg_restore will automatically prompt for a
password if the server demands password authentication. However, pg_restore 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 perform the restore. This option causes pg_restore
to issue a SET ROLE rolename command after connecting to the database. It is useful
when the authenticated user (specified by -U) lacks privileges needed by pg_restore,
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 restores to
be performed without violating the policy.

ENVIRONMENT

PGHOST
PGOPTIONS
PGPORT
PGUSER
Default connection parameters

This utility, like most other PostgreSQL utilities, also uses the environment variables
supported by libpq (see Section 31.14, “Environment Variables”, in the documentation).
However, it does not read PGDATABASE when a database name is not supplied.

DIAGNOSTICS

When a direct database connection is specified using the -d option, pg_restore internally
executes SQL statements. If you have problems running pg_restore, 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.

NOTES

If your installation has any local additions to the template1 database, be careful to load
the output of pg_restore 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;

The limitations of pg_restore are detailed below.

· When restoring data to a pre-existing table and the option --disable-triggers is used,
pg_restore emits commands to disable triggers on user tables before inserting the
data, then emits 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.

· pg_restore cannot restore large objects selectively; for instance, only those for a
specific table. If an archive contains large objects, then all large objects will be
restored, or none of them if they are excluded via -L, -t, or other options.

See also the pg_dump(1) documentation for details on limitations of pg_dump.

Once restored, it is wise to run ANALYZE on each restored table so the optimizer has
useful statistics; see Section 23.1.3, “Updating Planner Statistics”, in the documentation
and Section 23.1.6, “The Autovacuum Daemon”, in the documentation for more information.

EXAMPLES

Assume we have dumped a database called mydb into a custom-format dump file:

$ pg_dump -Fc mydb > db.dump

To drop the database and recreate it from the dump:

$ dropdb mydb
$ pg_restore -C -d postgres db.dump

The database named in the -d switch can be any database existing in the cluster;
pg_restore only uses it to issue the CREATE DATABASE command for mydb. With -C, data is
always restored into the database name that appears in the dump file.

To reload the dump into a new database called newdb:

$ createdb -T template0 newdb
$ pg_restore -d newdb db.dump

Notice we don't use -C, and instead connect directly to the database to be restored into.
Also note that we clone the new database from template0 not template1, to ensure it is
initially empty.

To reorder database items, it is first necessary to dump the table of contents of the
archive:

$ pg_restore -l db.dump > db.list

The listing file consists of a header and one line for each item, e.g.:

;
; Archive created at Mon Sep 14 13:55:39 2009
; dbname: DBDEMOS
; TOC Entries: 81
; Compression: 9
; Dump Version: 1.10-0
; Format: CUSTOM
; Integer: 4 bytes
; Offset: 8 bytes
; Dumped from database version: 8.3.5
; Dumped by pg_dump version: 8.3.8
;
;
; Selected TOC Entries:
;
3; 2615 2200 SCHEMA - public pasha
1861; 0 0 COMMENT - SCHEMA public pasha
1862; 0 0 ACL - public pasha
317; 1247 17715 TYPE public composite pasha
319; 1247 25899 DOMAIN public domain0 pasha

Semicolons start a comment, and the numbers at the start of lines refer to the internal
archive ID assigned to each item.

Lines in the file can be commented out, deleted, and reordered. For example:

10; 145433 TABLE map_resolutions postgres
;2; 145344 TABLE species postgres
;4; 145359 TABLE nt_header postgres
6; 145402 TABLE species_records postgres
;8; 145416 TABLE ss_old postgres

could be used as input to pg_restore and would only restore items 10 and 6, in that order:

$ pg_restore -L db.list db.dump

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