PostgreSQL is an open source, object-relational database built with a focus on extensibility, data integrity, and speed. Its concurrency support makes it fully ACID compliant, and it supports dynamic loading and catalog-driven operations to let users customize its data types, functions, and more.
You can migrate existing PostgreSQL databases from other cloud providers (such as AWS, Azure, and self-hosted databases) or from inside DigitalOcean to other clusters in your DigitalOcean account. Migrating a database establishes a connection with an existing database and replicates its contents to the new database cluster. If the existing database is continuously being written to, the migration process will continue until there is no more data to replicate or you manually stop the migration.
The online migration feature uses logical replication to migrate data from one database to another. Logical replication continuously streams the replication line-by-line, including any changes being written to the database during the migration, until the replication is stopped.
Depending on your database’s workload, you may need to develop a strategy on how best to cutover to your new database after the migration is complete.
To migrate an existing database to a DigitalOcean database cluster, you need to ensure logical replication is enabled on the source database, reference the source database’s connection credentials and to disable or update any firewalls between the databases.
Most cloud database providers have logical replication enabled by default, but if you are migrating a database from an on-premises server, you need to verify that logical replication is enabled on the database before migration. If your database is not set up for logical replication, the migration feature will not work. You can tell if your database is not set up for logical replication if your schemas migrate but your data does not during the migration.
You can enable logical replication on your database by editing the
postgresql.conf file of the PostgreSQL installation.
To enable logical replication on the source database, open
postgresql.conf in a text editor. It is located at
C:/Program Files/PostgreSQL/<YOUR-POSTGRESQL-VERSION-NUMBER>/data/postgresql.conf on Windows).
postgresql.conf, uncomment the parameter
wal_level and set it to the following:
wal_level = logical
Save the changes to the file and then restart PostgreSQL:
sudo service postgresql stop sudo service postgresql start
To check to see if logical replication has been enabled, run the following command from the PostgreSQL terminal:
It should return:
wal_level ----------- logical (1 row)
Before migrating an existing database, you need the database’s following credentials:
If you’re migrating a database that resides at DigitalOcean, you can locate your database’s public connection information and credentials under its Connection Details in the control panel. If your database resides at another provider, reference their documentation for further information.
To migrate an existing database, you also need to update or temporarily disable any firewalls protecting the databases to allow the databases to connect to each other.
To do this on the target DigitalOcean database, remove any trusted sources from the database cluster. Removing all trusted sources leaves the database open to all incoming connections. To keep your databases secure after migration, add the trusted sources back to the database.
If your source database resides at DigitalOcean, repeat the process of removing all trusted sources from the source database cluster.
If your source database resides outside of DigitalOcean, you may need to update or temporarily disable any firewalls protecting the database before attempting migration. Refer to your database provider’s documentation to see how to do this.
To migrate a PostgreSQL database from the DigitalOcean Control Panel, click Databases and then select the database you want to migrate to from your list of databases.
From the database’s Overview page, click the Actions button and then select Set Up Migration.
In the PostgreSQL migration window, click Continue, then enter the source database’s credentials. Once you have entered the source database’s credentials, click Start Migration. A migration status banner opens at the top of the Overview page and your target database’s data begins to transfer.
Once the migration begins, some features on both databases become unavailable. You can stop the migration at any time by clicking the Stop Migration button in the migration status banner. If you stop migration, the database retains any migrated data.