Akka.Persistence Migration Example

An example of how to migrate between Akka.Persistence implementations in Akka.NET using actors, Akka.NET serialization, and persistence configuration.

In this example, we will be migrating existing MongoDB database to PostgreSQL using the migration app.

Technologies Used

• Akka.Persistence.MongoDb as the source persistence database that will be migrated
• Akka.Persistence.MongoDb.Hosting
• Akka.Persistence.Sql targeting PostgreSQL database as the target database to migrate into
• Akka.Persistence.Sql.Hosting
• MongoDb
• NpgSql

Running The Example

To run this example, you will need to have docker installed on your computer.

Starting The Infrastructure

Database Docker Containers

There are 2 Powershell script provided to start a MongoDB and a PostgreSQL docker containers, we will need to start them before we start the application.

.\start-mongo.ps1

.\start-postgres.ps1

Seeding MongoDB

To seed the MongoDB database with data, you can either run the App.MongoDb SEED launch configuration from your IDE, or use this CLI command:

dotnet run --project .\src\App.MongoDb\App.MongoDb.csproj -- seed

The seeding app will persist 11,000 messages across 50 actors evenly (220 messages per actor), creating a snapshot every 50 messages. You should see the actors reporting its final state of 220 dataset like so:

Persistence ID Count: 50

╔════════════════════╤════════════════╤════════╗
║Persistence Id      │Last Sequence Nr│Checksum║
╠════════════════════╪════════════════╪════════╣
║persistent-worker-00│220             │1204500 ║
║persistent-worker-01│220             │1204720 ║
║persistent-worker-02│220             │1204940 ║
║persistent-worker-03│220             │1205160 ║
║persistent-worker-04│220             │1205380 ║
║persistent-worker-05│220             │1205600 ║
║persistent-worker-06│220             │1205820 ║
║persistent-worker-07│220             │1206040 ║
║persistent-worker-08│220             │1206260 ║
║persistent-worker-09│220             │1206480 ║
║persistent-worker-10│220             │1206700 ║
║persistent-worker-11│220             │1206920 ║
║persistent-worker-12│220             │1207140 ║
║persistent-worker-13│220             │1207360 ║
║persistent-worker-14│220             │1207580 ║
║persistent-worker-15│220             │1207800 ║
║persistent-worker-16│220             │1208020 ║
║persistent-worker-17│220             │1208240 ║
║persistent-worker-18│220             │1208460 ║
║persistent-worker-19│220             │1208680 ║
║persistent-worker-20│220             │1208900 ║
║persistent-worker-21│220             │1209120 ║
║persistent-worker-22│220             │1209340 ║
║persistent-worker-23│220             │1209560 ║
║persistent-worker-24│220             │1209780 ║
║persistent-worker-25│220             │1210000 ║
║persistent-worker-26│220             │1210220 ║
║persistent-worker-27│220             │1210440 ║
║persistent-worker-28│220             │1210660 ║
║persistent-worker-29│220             │1210880 ║
║persistent-worker-30│220             │1211100 ║
║persistent-worker-31│220             │1211320 ║
║persistent-worker-32│220             │1211540 ║
║persistent-worker-33│220             │1211760 ║
║persistent-worker-34│220             │1211980 ║
║persistent-worker-35│220             │1212200 ║
║persistent-worker-36│220             │1212420 ║
║persistent-worker-37│220             │1212640 ║
║persistent-worker-38│220             │1212860 ║
║persistent-worker-39│220             │1213080 ║
║persistent-worker-40│220             │1213300 ║
║persistent-worker-41│220             │1213520 ║
║persistent-worker-42│220             │1213740 ║
║persistent-worker-43│220             │1213960 ║
║persistent-worker-44│220             │1214180 ║
║persistent-worker-45│220             │1214400 ║
║persistent-worker-46│220             │1214620 ║
║persistent-worker-47│220             │1214840 ║
║persistent-worker-48│220             │1215060 ║
║persistent-worker-49│220             │1215280 ║
╚════════════════════╧════════════════╧════════╝

Note that each actor received 20 recovery event and stored 220 data in its state.

Migrating The Database

To start the database migration, run the Akka.Persistence.Migration app either using your IDE of through the CLI command:

dotnet run --project .\src\Akka.Persistence.Migration\Akka.Persistence.Migration.csproj

Validating The Migration Process

To validate that migration has been completed successfully, we will use the App.PostgreSql app. This app is practically identical to App.MongoDb, with the main difference that we swapped out Akka.Persistence.MongoDb with Akka.Persistence.Sql and it does not have the seeding code.

Run the App.PostgreSql app in your IDE or use the CLI command:

dotnet run --project .\src\App.PostgreSql\App.PostgreSql.csproj

All the data should be migrated over to PostgreSQL and you should see an identical output to App.MongoDb

Persistence ID Count: 50

╔════════════════════╤════════════════╤════════╗
║Persistence Id      │Last Sequence Nr│Checksum║
╠════════════════════╪════════════════╪════════╣
║persistent-worker-00│220             │1204500 ║
║persistent-worker-01│220             │1204720 ║
║persistent-worker-02│220             │1204940 ║
║persistent-worker-03│220             │1205160 ║
║persistent-worker-04│220             │1205380 ║
║persistent-worker-05│220             │1205600 ║
║persistent-worker-06│220             │1205820 ║
║persistent-worker-07│220             │1206040 ║
║persistent-worker-08│220             │1206260 ║
║persistent-worker-09│220             │1206480 ║
║persistent-worker-10│220             │1206700 ║
║persistent-worker-11│220             │1206920 ║
║persistent-worker-12│220             │1207140 ║
║persistent-worker-13│220             │1207360 ║
║persistent-worker-14│220             │1207580 ║
║persistent-worker-15│220             │1207800 ║
║persistent-worker-16│220             │1208020 ║
║persistent-worker-17│220             │1208240 ║
║persistent-worker-18│220             │1208460 ║
║persistent-worker-19│220             │1208680 ║
║persistent-worker-20│220             │1208900 ║
║persistent-worker-21│220             │1209120 ║
║persistent-worker-22│220             │1209340 ║
║persistent-worker-23│220             │1209560 ║
║persistent-worker-24│220             │1209780 ║
║persistent-worker-25│220             │1210000 ║
║persistent-worker-26│220             │1210220 ║
║persistent-worker-27│220             │1210440 ║
║persistent-worker-28│220             │1210660 ║
║persistent-worker-29│220             │1210880 ║
║persistent-worker-30│220             │1211100 ║
║persistent-worker-31│220             │1211320 ║
║persistent-worker-32│220             │1211540 ║
║persistent-worker-33│220             │1211760 ║
║persistent-worker-34│220             │1211980 ║
║persistent-worker-35│220             │1212200 ║
║persistent-worker-36│220             │1212420 ║
║persistent-worker-37│220             │1212640 ║
║persistent-worker-38│220             │1212860 ║
║persistent-worker-39│220             │1213080 ║
║persistent-worker-40│220             │1213300 ║
║persistent-worker-41│220             │1213520 ║
║persistent-worker-42│220             │1213740 ║
║persistent-worker-43│220             │1213960 ║
║persistent-worker-44│220             │1214180 ║
║persistent-worker-45│220             │1214400 ║
║persistent-worker-46│220             │1214620 ║
║persistent-worker-47│220             │1214840 ║
║persistent-worker-48│220             │1215060 ║
║persistent-worker-49│220             │1215280 ║
╚════════════════════╧════════════════╧════════╝