PostgreSQL Copy Database Made Easy

Summary: in this tutorial, you will learn how to copy a PostgreSQL database on the same server or from one server to another.

PostgreSQL copy database within the same server

Sometimes, you want to copy a PostgreSQL database within a database server for testing purposes.

PostgreSQL makes it easy to do so via the CREATE DATABASE statement, as follows:

CREATE DATABASE targetdb
WITH TEMPLATE sourcedb;

This statement copies the sourcedb to the targetdb. For example, to copy the dvdrental sample database to the dvdrental_test database, you use the following statement:

CREATE DATABASE dvdrental_test
WITH TEMPLATE dvdrental;

Depending on the size of the source database, copying may take some time to complete.

If the dvdrental database has active connections, you will encounter the following error:

ERROR:  source database "dvdrental" is being accessed by other users
DETAIL:  There is 1 other session using the database.

The following query returns the active connections:

SELECT pid, usename, client_addr
FROM pg_stat_activity
WHERE datname ='dvdrental';

To terminate the active connections to the dvdrental database, you use the following query:

SELECT pg_terminate_backend (pid)
FROM pg_stat_activity
WHERE datname = 'dvdrental';

After that, you can execute the CREATE TABLE WITH TEMPLATE statement again to copy the dvdrental database to dvdrental_test database.

PostgreSQL copy database from one server to another

There are several ways to copy a database between PostgreSQL database servers.

If the size of the source database is big and the connection between the database servers is slow, you can dump the source database to a file, copy the file to the remote server, and restore it:

First, dump the source database into a file.

pg_dump -U postgres -d sourcedb -f sourcedb.sql

Second, copy the dump file to the remote server.

Third, create a new database in the remote server:

CREATE DATABASE targetdb;

Finally, restore the dump file on the remote server:

psql -U postgres -d targetdb -f sourcedb.sql

Copying the dvdrental database example

The following steps illustrate how to copy the dvdrental database from the local server to the remote server.

First, dump the dvdrental database into a dump file such as dvdrental.sql:

pg_dump -U postgres -O dvdrental -f dvdrental.sql

Second, copy the dump file to the remote server.

Third, create the dvdrental database on the remote server:

CREATE DATABASE dvdrental;

Fourth, restore the dvdrental.sql dump file in the remote server:

psql -U postgres -d dvdrental -f dvdrental.sql

If the connection between the servers is fast and the size of the database is not big, you can use the following command:

pg_dump -C -h local -U localuser sourcedb | psql -h remote -U remoteuser targetdb

For example, to copy the dvdrental database from the localhost server to the remote server, you can execute the following command:

pg_dump -C -h localhost -U postgres dvdrental | psql -h remote -U postgres dvdrental

In this tutorial, you have learned how to copy a PostgreSQL database within a database server, or from one database server to another.