Simple data migration from MongoDb to PostgreSQL

This tiny tool is used for easy data migration from MongoDb database to PostgreSQL database. It uses appropriate ORMs: mongoose and knex respectively to transfer data.

Requirements

• Node.js 13+
• MongoDb 4+
• PostgreSQL 12+

Usage

1. Install package

$ yarn add mongo-to-postgres

OR

$ npm i mongo-to-postgres

2. Create file migrate.js, set migration settings in it

IMPORTANT NOTES

1. You MUST respect the order of the tables. Tables with foreign keys MUST BE placed AFTER tables, from which these keys are.

2. This sample assumes that you have postgres database with schema, containing empty tables.

import migrate from 'mongo-to-postgres';

migrate({
  // Define connection strings
  connections: {
    mongo: 'mongodb://localhost/dbname',
    postgres: 'postgres://postgres:secret@localhost:5432/dbname'
  },
  // Define your database migration settings
  collections: [
    {
    collectionName: 'department',  // collection name in Mongo
    tableName: 'departments',      // table name in Postgres
    fieldsRename: [
      ['createdAt', 'created_at'], // set new name for field (optional)
      ['updatedAt', 'updated_at']  // set new name for other field (optional)
    ],
    fieldsRedefine: [
      ['dep_type', 1]              // force to set value for all records (optional)
    ]
  },
  {
    collectionName: 'award',       // collection name in Mongo
    tableName: 'awards',           // table name in Postgres
  },
  {
    collectionName: 'employee',    // collection name in Mongo
    tableName: 'employees',        // table name in Postgres
    foreignKeys: {
      department: 'department',    // foreign keys (field: collection) (optional)
    },
    links: {                       // "many-to-many" links
      awards: ['emplyees__awards', 'employee_id', 'award_id']
    }
  }
  ]
});

3. Set package.json "type" field

{
  "type": "module",
  "dependencies": {
    "mongo-to-postgres": "^0.0.5"
  }
}

4. Run migration

$ node migrate.js