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PG_DUMP(1) PostgreSQL Client Applications PG_DUMP(1)
NAME
pg_dump - extract a PostgreSQL database into a script file or other archive file
SYNOPSIS
pg_dump [ 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 pro-
vides 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 com-
pressed 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 manipu-
lated with standard Unix 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 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 speci-
fied for the connection is used.
-a
--data-only
Dump only the data, not the schema (data definitions).
This option is only meaningful for the plain-text format. For the archive formats,
you can specify the option when you call pg_restore.
-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 (the commands for) creat-
ing them.
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 you
connect to before running the script.)
This option is only meaningful for the plain-text format. For the archive formats,
you can 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-PostgreSQL
databases. Also, 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 ta-
ble contents. Note that the restore might fail altogether if you have rearranged
column order. The -D option is safe against column order changes, 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-PostgreSQL databases. Also, 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.
-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. 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
plain Output a plain-text SQL script file (the default).
c
custom 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.
t
tar 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.
-i
--ignore-version
Ignore version mismatch between pg_dump and the database server.
pg_dump can dump from servers running previous releases of PostgreSQL, but very old
versions are not supported anymore (currently, those prior to 7.0). Dumping from a
server newer than pg_dump is likely not to work at all. Use this option if you
need to override the version check (and if pg_dump then fails, don't say you
weren't warned).
-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 multi-
ple -n switches. Also, the schema parameter is interpreted as a pattern according
to the same rules used by psql's \d commands (see Patterns [psql(1)]), 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.
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 guar-
antee 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.
-S username
--superuser=username
Specify the superuser user name to use when disabling triggers. This is only rele-
vant 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) 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
[psql(1)]), 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.
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 guar-
antee 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.
-x
--no-privileges
--no-acl
Prevent dumping of access privileges (grant/revoke commands).
--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 trig-
gers 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.
--use-set-session-authorization
Output SQL-standard SET SESSION AUTHORIZATION commands instead of ALTER OWNER com-
mands 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 prop-
erly. Also, a dump using SET SESSION AUTHORIZATION will certainly require superuser
privileges to restore correctly, whereas ALTER OWNER requires lesser privileges.
-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.
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
--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 pass-
word 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.
ENVIRONMENT
PGDATABASE
PGHOST
PGPORT
PGUSER Default connection parameters.
This utility, like most other PostgreSQL utilities, also uses the environment variables
supported by libpq (see 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.
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 with-
out any local additions, copy from template0 not template1, for example:
CREATE DATABASE foo WITH TEMPLATE template0;
pg_dump has a limitation; when a data-only dump is chosen and the option --disable-trig-
gers 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 might be left in the wrong state.
Members of tar archives are limited to a size less than 8 GB. (This is an inherent limi-
tation of the tar file format.) Therefore this format cannot be used if the textual repre-
sentation 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 good performance. 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 loaded into newer PostgreSQL databases. It also can read older PostgreSQL
databases. However, it usually cannot read newer PostgreSQL databases or produce dump out-
put that can be loaded into older database versions. To do this, manual editing of the
dump file might be required.
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 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 dou-
ble-quote the name; else it will be folded to lower case (see Patterns [psql(1)]). 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)
Application 2011-09-22 PG_DUMP(1)
Generated by $Id: phpMan.php,v 4.49 2006/02/26 13:18:18 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2012-05-26 02:01 @38.107.179.240 Crawled by CCBot/1.0 (+http://www.commoncrawl.org/bot.html)