Database Connector (MySQL)

Overview

A database connector is the bridge between Prisma and the underlying database. The MySQL connector is used to connect a Prisma server to a MySQL database.

The core responsibilities of a database connector are:

• Translate Prisma client requests into SQL
• Send the generated SQL query to the database
• Return the database results as back to the Prisma client
• Perform database migrations (optional)

When configuring your Prisma server with Docker, you need to specify which connector you'd like to use in order to connect to a certain database. You provide this info via the connector property:

PRISMA_CONFIG: |
  managementApiSecret: __YOUR_MANAGEMENT_API_SECRET__
  port: 4466
  databases:
    default:
      connector: mysql
      migrations: __ENABLE_DB_MIGRATIONS__
      host: __YOUR_DATABASE_HOST__
      port: __YOUR_DATABASE_PORT__
      user: __YOUR_DATABASE_USER__
      password: __YOUR_DATABASE_PASSWORD__
      connectionLimit: __YOUR_CONNECTION_LIMIT__
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Migrations

The migrations property in the PRISMA_CONFIG environment variable specifies whether the database connector is able to make changes to the underlying database schema.

For existing databases (that might already be powering production applications), it is useful to configure the Prisma server to not migrate the connected database. This ensures you're not accidentally introducing unwanted schema changes or lose data.

PRISMA_CONFIG: |
  managementApiSecret: __YOUR_MANAGEMENT_API_SECRET__
  port: 4466
  databases:
    default:
      connector: postgres
      migrations: __ENABLE_DB_MIGRATIONS__
      host: __YOUR_DATABASE_HOST__
      port: __YOUR_DATABASE_PORT__
      user: __YOUR_DATABASE_USER__
      password: __YOUR_DATABASE_PASSWORD__
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Database migrations

Enabling migrations through Prisma

If migrations is set to true, deploying a Prisma service migrates the structure of the connected database. In these cases, the Prisma CLI will be the main interface to govern the structure of the database based on the datamodel of your services:

PRISMA_CONFIG: |
  managementApiSecret: __YOUR_MANAGEMENT_API_SECRET__
  port: 4466
  databases:
    default:
      connector: postgres
      migrations: true
      host: __YOUR_DATABASE_HOST__
      port: __YOUR_DATABASE_PORT__
      user: __YOUR_DATABASE_USER__
      password: __YOUR_DATABASE_PASSWORD__
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Disabling migrations through Prisma

If migrations is set to false, the database schema is "locked" and Prisma won't perform any changes on it:

PRISMA_CONFIG: |
  managementApiSecret: __YOUR_MANAGEMENT_API_SECRET__
  port: 4466
  databases:
    default:
      connector: postgres
      migrations: false
      host: __YOUR_DATABASE_HOST__
      port: __YOUR_DATABASE_PORT__
      user: __YOUR_DATABASE_USER__
      password: __YOUR_DATABASE_PASSWORD__
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Managing database connections

The connectionLimit property in PRISMA_CONFIG determines the number of database connections a Prisma service is going to use.

Database schema

Prisma currently maintains a table called _RelayId. This table is there for historic reasons and will be removed soon.