Migrating the Database from MySQL to PostgreSQL for OroCommerce, OroCRM or OroPlatform 

Make a MySQL Database Backup 

Before starting the migration process, it is crucial to create a backup of the existing MySQL database. This backup will ensure that you have a fallback option in case anything goes wrong during the migration process.

Create an Empty PostgreSQL Database 

Next, you need to create an empty PostgreSQL database. If you are running PostgreSQL in a Docker container, make sure it has enough shared memory. You can do this by setting the shm_size: 1g option for the pgsql service.

Create a Migration Config 

Once the empty PostgreSQL database is set up, create a migration configuration file that specifies the migration process. The following is a sample migration config that can be used for this process:

LOAD DATABASE
    FROM      mysql://dbuser:dbpass@localhost:3306/old_db_name
    INTO postgresql://dbuser:dbpass@localhost:5432/new_db_name
alter schema 'old_db_name' rename to 'public'
CAST type datetime to timestamp /*(DC2Type:datetime)*/ drop default drop not null using zero-dates-to-null,
type int with extra auto_increment when (< precision 12) to serial drop typemod,
type int with extra auto_increment when (>= 12 precision) to bigserial drop typemod,
type int when (< precision 12) to int drop typemod,
type int when (>= 12 precision) to bigint drop typemod,
type longtext to text using remove-null-characters,
TYPE smallint when unsigned TO smallint drop typemod,
TYPE bigint when unsigned TO bigint drop typemod,
TYPE bigint TO bigint drop typemod,
TYPE json TO jsonb drop typemod,
TYPE int when (unsigned && >= 10 precision) TO bigint drop typemod
;

In this configuration file, replace the database credentials with your own. Also, in alter schema ``old_db_name`` rename to ``public``, replace old_db_name with the MySQL table name.

Migrate the Database to PostgreSQL Using Pgloader 

Use pgloader to migrate the database to PostgreSQL with the above config by running the following command:

pgloader oro-mysql-pgsql.conf

Switch the Application to the PostgreSQL Database 

Once the migration configuration file is set up, switch the OroCommerce application to use the new PostgreSQL database. To do this, edit the config/parameters.yml file and change the database settings to point to the new PostgreSQL database.

Clear the Application Cache 

After making changes to the OroCommerce configuration, it is essential to remove the application cache to ensure that the changes take effect. You can do this by running the following command:

php bin/console cache:clear --env=prod

Test the Application 

With the application cache cleared, test the application and ensure that everything has been migrated successfully. Perform a few basic tests to make sure that everything is working as expected.

Follow the Standard Upgrade Process 

Finally, to migrate an application to version 5.1.* where PostgreSQL is the default and only supported version for all community and enterprise edition applications, follow the standard upgrade process provided by OroCommerce. This process may vary depending on the version of OroCommerce you are currently running.

In conclusion, switching the database from MySQL to PostgreSQL for OroCommerce requires careful planning and execution. By following the steps outlined above, you can ensure a smooth and successful migration.