INFORMATICS

pg restore manual:

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

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. (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, --ignore-version
           A deprecated option that is now ignored.

       -I index, --index=index
           Restore definition of named index only.

       -j number-of-jobs, --jobs=number-of-jobs
           Run the most time-consuming parts of pg_restorethose which load data, create indexes,
           or create constraintsusing 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. 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.

       -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.

       -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.

       --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 ROLErolename 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.


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

1. Restore a database with psql command
Recently, one of our customers approached us to restore the Postgres database from files. His database backup was a plaintext file containing SQL scripts.

For restoring, our Support Engineers run the psql command.

psql -U user_db user_name < dump_db.sql
Here, user_db and user_name are the database user and database name respectively. And, dump_db.sql is the name of the backup file.

This command effectively restored the Postgres database from files.

 

2. Restore a database with pg_restore command
Similarly, another method to restore the Postgres database is using the pg_restore command.

If the backup file created by pg_dump is of custom, directory or archive format, we use the command.

pg_restore -d user_db /path/to/your/file/dump_db.tar -c -U user_name
Here, -c prompts to drop the database before recreating it.

By default, pg_restore has various options similar to this.