Creating a copy of a database in PostgreSQL

Postgres allows the use of any existing database on the server as a template when creating a new database. I'm not sure whether pgAdmin gives you the option on the create database dialog but you should be able to execute the following in a query window if it doesn't:

CREATE DATABASE newdb WITH TEMPLATE originaldb OWNER dbuser;

Still, you may get:

ERROR:  source database "originaldb" is being accessed by other users

To disconnect all other users from the database, you can use this query:

SELECT pg_terminate_backend(pg_stat_activity.pid) FROM pg_stat_activity 
WHERE pg_stat_activity.datname = 'originaldb' AND pid <> pg_backend_pid();

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A command-line version of Bell's answer:

createdb -O ownername -T originaldb newdb

This should be run under the privileges of the database master, usually postgres.

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To clone an existing database with postgres you can do that

/* KILL ALL EXISTING CONNECTION FROM ORIGINAL DB (sourcedb)*/
SELECT pg_terminate_backend(pg_stat_activity.pid) FROM pg_stat_activity 
WHERE pg_stat_activity.datname = 'SOURCE_DB' AND pid <> pg_backend_pid();

/* CLONE DATABASE TO NEW ONE(TARGET_DB) */
CREATE DATABASE TARGET_DB WITH TEMPLATE SOURCE_DB OWNER USER_DB;

IT will kill all the connection to the source db avoiding the error

ERROR:  source database "SOURCE_DB" is being accessed by other users

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In production environment, where the original database is under traffic, I'm simply using:

pg_dump production-db | psql test-db

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Don't know about pgAdmin, but pgdump gives you a dump of the database in SQL. You only need to create a database by the same name and do

psql mydatabase < my dump

to restore all of the tables and their data and all access privileges.

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First, sudo as the database user:

sudo su postgres

Go to PostgreSQL command line:

psql

Create the new database, give the rights and exit:

CREATE DATABASE new_database_name;
GRANT ALL PRIVILEGES ON DATABASE new_database_name TO my_user;
\d

Copy structure and data from the old database to the new one:

pg_dump old_database_name | psql new_database_name

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In pgAdmin you can make a backup from your original database, and then just create a new database and restore from the backup just created:

Right click the source database, Backup... and dump to a file. Right click, New Object, New Database... and name the destination. Right click the new database, Restore... and select your file.

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Copying an "under load" db

I pieced this approach together with the examples from above. I'm working on an "under load" server and got the error when I attempted the approach from @zbyszek. I also was after a "command line only" solution.

createdb: database creation failed: ERROR: source database "exampledb" is being accessed by other users.

Here's what worked for me (Commands prepended with nohup to move output into a file and protect from a server disconnect):

nohup pg_dump exampledb > example-01.sql createdb -O postgres exampledbclone_01 my user is "postgres" nohup psql exampledbclone_01 < example-01.sql

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What's the correct way to copy entire database (its structure and data) to a new one in pgAdmin?

Answer:

CREATE DATABASE newdb WITH TEMPLATE originaldb;

Tried and tested.

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Here's the whole process of creating a copying over a database using only pgadmin4 GUI (via backup and restore)

Postgres comes with Pgadmin4. If you use macOS you can press CMD+SPACE and type pgadmin4 to run it. This will open up a browser tab in chrome.

Steps for copying

1. Create the backup

Do this by rightclicking the database -> "backup"

https://i.stack.imgur.com/2hQt9.png

2. Give the file a name.

Like test12345. Click backup. This creates a binary file dump, it's not in a .sql format

https://i.stack.imgur.com/FyEZm.png

3. See where it downloaded

There should be a popup at the bottomright of your screen. Click the "more details" page to see where your backup downloaded to

https://i.stack.imgur.com/5cXqM.png

4. Find the location of downloaded file

In this case, it's /users/vincenttang

https://i.stack.imgur.com/vJiyy.png

5. Restore the backup from pgadmin

Assuming you did steps 1 to 4 correctly, you'll have a restore binary file. There might come a time your coworker wants to use your restore file on their local machine. Have said person go to pgadmin and restore

Do this by rightclicking the database -> "restore"

https://i.stack.imgur.com/bAUhb.png

6. Select file finder

Make sure to select the file location manually, DO NOT drag and drop a file onto the uploader fields in pgadmin. Because you will run into error permissions. Instead, find the file you just created:

https://i.stack.imgur.com/0FL3F.png

7. Find said file

You might have to change the filter at bottomright to "All files". Find the file thereafter, from step 4. Now hit the bottomright "Select" button to confirm

https://i.stack.imgur.com/woFcW.png

8. Restore said file

You'll see this page again, with the location of the file selected. Go ahead and restore it

https://i.stack.imgur.com/i7cTv.png

9. Success

If all is good, the bottom right should popup an indicator showing a successful restore. You can navigate over to your tables to see if the data has been restored propery on each table.

10. If it wasn't successful:

Should step 9 fail, try deleting your old public schema on your database. Go to "Query Tool"

https://i.stack.imgur.com/bqmyP.png

Execute this code block:

DROP SCHEMA public CASCADE; CREATE SCHEMA public;

https://i.stack.imgur.com/BaHyr.png

Now try steps 5 to 9 again, it should work out

EDIT - Some additional notes. Update PGADMIN4 if you are getting an error during upload with something along the lines of "archiver header 1.14 unsupported version" during restore

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From the documentation, using createdb or CREATE DATABASE with templates is not encouraged:

Although it is possible to copy a database other than template1 by specifying its name as the template, this is not (yet) intended as a general-purpose “COPY DATABASE” facility. The principal limitation is that no other sessions can be connected to the template database while it is being copied. CREATE DATABASE will fail if any other connection exists when it starts; otherwise, new connections to the template database are locked out until CREATE DATABASE completes.

pg_dump or pg_dumpall is a good way to go for copying database AND ALL THE DATA. If you are using a GUI like pgAdmin, these commands are called behind the scenes when you execute a backup command. Copying to a new database is done in two phases: Backup and Restore

pg_dumpall saves all of the databases on the PostgreSQL cluster. The disadvantage to this approach is that you end up with a potentially very large text file full of SQL required to create the database and populate the data. The advantage of this approach is that you get all of the roles (permissions) for the cluster for free. To dump all databases do this from the superuser account

pg_dumpall > db.out

and to restore

psql -f db.out postgres

pg_dump has some compression options that give you much smaller files. I have a production database I backup twice a day with a cron job using

pg_dump --create --format=custom --compress=5 --file=db.dump mydatabase

where compress is the compression level (0 to 9) and create tells pg_dump to add commands to create the database. Restore (or move to new cluster) by using

pg_restore -d newdb db.dump

where newdb is the name of the database you want to use.

Other things to think about

PostgreSQL uses ROLES for managing permissions. These are not copied by pg_dump. Also, we have not dealt with the settings in postgresql.conf and pg_hba.conf (if you're moving the database to another server). You'll have to figure out the conf settings on your own. But there is a trick I just discovered for backing up roles. Roles are managed at the cluster level and you can ask pg_dumpall to backup just the roles with the --roles-only command line switch.

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For those still interested, I have come up with a bash script that does (more or less) what the author wanted. I had to make a daily business database copy on a production system, this script seems to do the trick. Remember to change the database name/user/pw values.

#!/bin/bash

if [ 1 -ne $# ]
then
  echo "Usage `basename $0` {tar.gz database file}"
  exit 65;
fi

if [ -f "$1" ]
then
  EXTRACTED=`tar -xzvf $1`
  echo "using database archive: $EXTRACTED";
else
  echo "file $1 does not exist"
  exit 1
fi


PGUSER=dbuser
PGPASSWORD=dbpw
export PGUSER PGPASSWORD

datestr=`date +%Y%m%d`


dbname="dbcpy_$datestr"
createdbcmd="CREATE DATABASE $dbname WITH OWNER = postgres ENCODING = 'UTF8' TABLESPACE = pg_default LC_COLLATE = 'en_US.UTF-8' LC_CTYPE = 'en_US.UTF-8' CONNECTION LIMIT = -1;"
dropdbcmp="DROP DATABASE $dbname"

echo "creating database $dbname"
psql -c "$createdbcmd"

rc=$?
if [[ $rc != 0 ]] ; then
  rm -rf "$EXTRACTED"
  echo "error occured while creating database $dbname ($rc)"
  exit $rc
fi


echo "loading data into database"
psql $dbname < $EXTRACTED > /dev/null

rc=$?

rm -rf "$EXTRACTED"

if [[ $rc != 0 ]] ; then
  psql -c "$dropdbcmd"
  echo "error occured while loading data to database $dbname ($rc)"
  exit $rc
fi


echo "finished OK"

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PostgreSQL 9.1.2:

$ CREATEDB new_db_name -T orig_db_name -O db_user;

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To create database dump

cd /var/lib/pgsql/
pg_dump database_name> database_name.out

To resote database dump

psql -d template1
CREATE DATABASE database_name WITH  ENCODING 'UTF8' LC_CTYPE 'en_US.UTF-8' LC_COLLATE 'en_US.UTF-8' TEMPLATE template0;
CREATE USER  role_name WITH PASSWORD 'password';
ALTER DATABASE database_name OWNER TO role_name;
ALTER USER role_name CREATEDB;
GRANT ALL PRIVILEGES ON DATABASE database_name to role_name;


CTR+D(logout from pgsql console)
cd /var/lib/pgsql/

psql -d database_name -f database_name.out

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If the database has open connections, this script may help. I use this to create a test database from a backup of the live-production database every night. This assumes that you have an .SQL backup file from the production db (I do this within webmin).

#!/bin/sh

dbname="desired_db_name_of_test_enviroment"
username="user_name"
fname="/path to /ExistingBackupFileOfLive.sql"

dropdbcmp="DROP DATABASE $dbname"
createdbcmd="CREATE DATABASE $dbname WITH OWNER = $username "

export PGPASSWORD=MyPassword



echo "**********"
echo "** Dropping $dbname"
psql -d postgres -h localhost -U "$username" -c "$dropdbcmp"

echo "**********"
echo "** Creating database $dbname"
psql -d postgres -h localhost -U "$username" -c "$createdbcmd"

echo "**********"
echo "** Loading data into database"
psql -d postgres -h localhost -U "$username" -d "$dbname" -a -f "$fname"

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Using pgAdmin, disconnect the database that you want to use as a template. Then you select it as the template to create the new database, this avoids getting the already in use error.

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If you want to copy whole schema you can make a pg_dump with following command:

pg_dump -h database.host.com -d database_name -n schema_name -U database_user --password

And when you want to import that dump, you can use:

psql "host=database.host.com user=database_user password=database_password dbname=database_name options=--search_path=schema_name" -f sql_dump_to_import.sql

More info about connection strings: https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING

Or then just combining it in one liner:

pg_dump -h database.host.com -d postgres -n schema_name -U database_user --password | psql "host=database.host.com user=database_user password=database_password dbname=database_name options=--search_path=schema_name”

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Open the Main Window in pgAdmin and then open another Query Tools Window In the main windows in pgAdmin,

Disconnect the "templated" database that you want to use as a template.

Goto the Query Tools Window

Run 2 queries as below

SELECT pg_terminate_backend(pg_stat_activity.pid) 
    FROM pg_stat_activity 
    WHERE pg_stat_activity.datname = 'TemplateDB' AND pid <> pg_backend_pid(); 

(The above SQL statement will terminate all active sessions with TemplateDB and then you can now select it as the template to create the new TargetDB database, this avoids getting the already in use error.)

CREATE DATABASE 'TargetDB'
  WITH TEMPLATE='TemplateDB'
       CONNECTION LIMIT=-1;

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pgAdmin4:

1.Select DB you want to copy and disconnect it

Rightclick "Disconnect DB"

2.Create a new db next to the old one:

Give it a name.

In the "definition" tab select the first table as an Template (dropdown menu)

Hit create and just left click on the new db to reconnect.

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New versions of pgAdmin (definitely 4.30) support creating new databases from template. All you need to populate are new database name and existing template database.

https://i.stack.imgur.com/bjtXp.png

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CREATE DATABASE newdb WITH TEMPLATE originaldb OWNER dbuser;

If you have using Ubuntu. 1 way createdb -O Owner -T old_db_name new_db_name

2 way createdb test_copy pg_dump old_db_name | psql test_copy

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Try this:

CREATE DATABASE newdb WITH ENCODING='UTF8' OWNER=owner TEMPLATE=templatedb LC_COLLATE='en_US.UTF-8' LC_CTYPE='en_US.UTF-8' CONNECTION LIMIT=-1;

gl XD

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