nowdatabase/documentation/technical_explanations.md

Database

DB-dump restoring process

The mariadb-container by default executes all .sql files it finds in the containers /docker-entrypoint-initdb.d/ directory when the container is run the first time. The data directory is mounted there. It contains an initialization file (restore_and_create.sql) which will then restore the database from the sql-dumpfiles in sqlfiles/, and also create a user 'now_test'@'localhost' with a password defined as MARIADB_PASSWORD in the .db.dev.env file for the database.

Accessing database inside docker

docker exec -it nowdb-db mariadb -u now_test -p --database now_test

Enter the password defined in .dev.env.

Updating prisma-schema

If the database schema is changed, prisma-schema must be also updated. The smart prisma-way would be to run migrations via prisma, but I did this:

• The database was modified directly in SQL
• Anon-db dump was updated to reflect the changes by hand (for both the table structure and the data inputted to it)
• Also the test-db dump used locally was changed by hand, but this may be more complicated if theres a lot of data - in which case a new dump must be taken from the db after changes
  • Notice that for the db-container to initialize data, you must remove the container and then the volume and rebuild
• I ran the dev version of the app npm run dev
• I ran docker exec -it nowdb-backend-dev npx prisma db pull
• The schema was updated and the changes can be committed to github.
• After any schema update, to run the app, the Prisma client must be generated again (the client is located in "prisma/generated"). I did it by running npm run prisma in backend/ directory (outside of docker). Running it inside the container would not re-generate it correctly, not sure why.

Prisma documentation: https://www.prisma.io/docs/orm/reference/prisma-cli-reference#db-pull

Mariadb-connector and transactions

Prisma does not have proper support for connecting to multiple databases, and transactionality between them is therefore impossible. We need transactional write to both now and now_log databases. Therefore we use mariadb-connector for the write operations that need to be logged into the log-database.