Sequelize: Many-To-Many relation between MariaDB and Postgres - postgresql

Question

Little Background Story
Here is my scenario, I have a database named Location in my MariaDB, and I have a User database in my Postgres. I want to chain two of them in my Postgres DB. So I have two tables users and userLocations. Oh yeah, a nice thing to note is that I only have access to read (SELECT and CREATE VIEW) from LocationDB, and connecting to UserDB as root. Yes I have successfully authenticate() both of them. I even able to receive data from LocationDB however the only problem right now is creating that relation between User and Location. Error logs available on the bottom.
Here is my models:
models/user.js
// ... Connection to UserDB (uses Postgres)
const UserDB = require('../datasources/user-db')
const User = UserDB.define('user', {
id: { type: Sequelize.INTEGER, primaryKey: true, autoIncrement: true },
name: { type: Sequelize.STRING, allowNull: false }
})
module.exports = User
models/location.js
// Connection to LocationDB (uses MariaDB)
const LocationDB = require('../datasources/location-db')
const Location = LocationDB.define('ms_location', {
id_Location: { type: Sequelize.INTEGER, primaryKey: true },
name_Location: { type: Sequelize.STRING, allowNull: false }
}, { timestamps: false, freezeTableName: true })
module.exports = Location
models/user-location.js
// ... Connection to UserDB (uses Postgres)
const UserDB = require('../datasources/user-db')
const UserLocation = UserDB.define('userLocation', {
id: { type: Sequelize.INTEGER, primaryKey: true, autoIncrement: true }
})
module.exports = UserLocation
app.js
const Location = require('./models/location')
const User = require('./models/user')
const UserLocation = require('./models/user-location')
User.belongsToMany(Location, { through: UserLocation })
This is a minified version of the case, if you need more information please do ask as I am still new to sequelize as well
The error log: (sorry I don't have any idea to beautify it)
{ SequelizeDatabaseError: relation "ms_location" does not exist
at Query.formatError (<path-to-project>/node_modules/.registry.npmjs.org/sequelize/5.8.6/node_modules/sequelize/lib/dialects/postgres/query.js:354:16)
at query.catch.err (<path-to-project>/node_modules/.registry.npmjs.org/sequelize/5.8.6/node_modules/sequelize/lib/dialects/postgres/query.js:71:18)
at tryCatcher (<path-to-project>/node_modules/.registry.npmjs.org/bluebird/3.5.5/node_modules/bluebird/js/release/util.js:16:23)
at Promise._settlePromiseFromHandler (<path-to-project>/node_modules/.registry.npmjs.org/bluebird/3.5.5/node_modules/bluebird/js/release/promise.js:517:31)
at Promise._settlePromise (<path-to-project>/node_modules/.registry.npmjs.org/bluebird/3.5.5/node_modules/bluebird/js/release/promise.js:574:18)
at Promise._settlePromise0 (<path-to-project>/node_modules/.registry.npmjs.org/bluebird/3.5.5/node_modules/bluebird/js/release/promise.js:619:10)
at Promise._settlePromises (<path-to-project>/node_modules/.registry.npmjs.org/bluebird/3.5.5/node_modules/bluebird/js/release/promise.js:695:18)
at _drainQueueStep (<path-to-project>/node_modules/.registry.npmjs.org/bluebird/3.5.5/node_modules/bluebird/js/release/async.js:138:12)
at _drainQueue (<path-to-project>/node_modules/.registry.npmjs.org/bluebird/3.5.5/node_modules/bluebird/js/release/async.js:131:9)
at Async._drainQueues (<path-to-project>/node_modules/.registry.npmjs.org/bluebird/3.5.5/node_modules/bluebird/js/release/async.js:147:5)
at Immediate.Async.drainQueues [as _onImmediate] (<path-to-project>/node_modules/.registry.npmjs.org/bluebird/3.5.5/node_modules/bluebird/js/release/async.js:17:14)
at runCallback (timers.js:705:18)
at tryOnImmediate (timers.js:676:5)
at processImmediate (timers.js:658:5)
name: 'SequelizeDatabaseError',
parent:
{ error: relation "ms_location" does not exist
at Connection.parseE (<path-to-project>/node_modules/.registry.npmjs.org/pg/7.11.0/node_modules/pg/lib/connection.js:602:11)
at Connection.parseMessage (<path-to-project>/node_modules/.registry.npmjs.org/pg/7.11.0/node_modules/pg/lib/connection.js:399:19)
at Socket.<anonymous> (<path-to-project>/node_modules/.registry.npmjs.org/pg/7.11.0/node_modules/pg/lib/connection.js:121:22)
at Socket.emit (events.js:189:13)
at addChunk (_stream_readable.js:284:12)
at readableAddChunk (_stream_readable.js:265:11)
at Socket.Readable.push (_stream_readable.js:220:10)
at TCP.onStreamRead [as onread] (internal/stream_base_commons.js:94:17)
name: 'error',
length: 107,
severity: 'ERROR',
code: '42P01',
detail: undefined,
hint: undefined,
position: undefined,
internalPosition: undefined,
internalQuery: undefined,
where: undefined,
schema: undefined,
table: undefined,
column: undefined,
dataType: undefined,
constraint: undefined,
file: 'namespace.c',
line: '426',
routine: 'RangeVarGetRelidExtended',
sql:
'CREATE TABLE IF NOT EXISTS "userLocations" ("id" SERIAL , "createdAt" TIMESTAMP WITH TIME ZONE NOT NULL, "updatedAt" TIMESTAMP WITH TIME ZONE NOT NULL, "userId" INTEGER REFERENCES "users" ("id") ON DELETE CASCADE ON UPDATE CASCADE, "msLocationIdLocation" INTEGER REFERENCES "ms_location" ("id_Location") ON DELETE CASCADE ON UPDATE CASCADE, UNIQUE ("userId", "msLocationIdLocation"), PRIMARY KEY ("id"));' },
original:
{ error: relation "ms_location" does not exist
at Connection.parseE (<path-to-project>/node_modules/.registry.npmjs.org/pg/7.11.0/node_modules/pg/lib/connection.js:602:11)
at Connection.parseMessage (<path-to-project>/node_modules/.registry.npmjs.org/pg/7.11.0/node_modules/pg/lib/connection.js:399:19)
at Socket.<anonymous> (<path-to-project>/node_modules/.registry.npmjs.org/pg/7.11.0/node_modules/pg/lib/connection.js:121:22)
at Socket.emit (events.js:189:13)
at addChunk (_stream_readable.js:284:12)
at readableAddChunk (_stream_readable.js:265:11)
at Socket.Readable.push (_stream_readable.js:220:10)
at TCP.onStreamRead [as onread] (internal/stream_base_commons.js:94:17)
name: 'error',
length: 107,
severity: 'ERROR',
code: '42P01',
detail: undefined,
hint: undefined,
position: undefined,
internalPosition: undefined,
internalQuery: undefined,
where: undefined,
schema: undefined,
table: undefined,
column: undefined,
dataType: undefined,
constraint: undefined,
file: 'namespace.c',
line: '426',
routine: 'RangeVarGetRelidExtended',
sql:
'CREATE TABLE IF NOT EXISTS "userLocations" ("id" SERIAL , "createdAt" TIMESTAMP WITH TIME ZONE NOT NULL, "updatedAt" TIMESTAMP WITH TIME ZONE NOT NULL, "userId" INTEGER REFERENCES "users" ("id") ON DELETE CASCADE ON UPDATE CASCADE, "msLocationIdLocation" INTEGER REFERENCES "ms_location" ("id_Location") ON DELETE CASCADE ON UPDATE CASCADE, UNIQUE ("userId", "msLocationIdLocation"), PRIMARY KEY ("id"));' },
sql:
'CREATE TABLE IF NOT EXISTS "userLocations" ("id" SERIAL , "createdAt" TIMESTAMP WITH TIME ZONE NOT NULL, "updatedAt" TIMESTAMP WITH TIME ZONE NOT NULL, "userId" INTEGER REFERENCES "users" ("id") ON DELETE CASCADE ON UPDATE CASCADE, "msLocationIdLocation" INTEGER REFERENCES "ms_location" ("id_Location") ON DELETE CASCADE ON UPDATE CASCADE, UNIQUE ("userId", "msLocationIdLocation"), PRIMARY KEY ("id"));' }

Answer 1

You've told Sequelize that you have a table called user and a table called msLocation and that the two are related through another table called userLocation. (Or is it userLocations? Your code and error message are inconsistent.)
It looks like Sequelize is trying to create the userLocations table UserDB but it's failing because as part of the table definition, it's trying to create a foreign key reference to ms_location:
"msLocationIdLocation" INTEGER REFERENCES "ms_location" ("id_Location")
ON DELETE CASCADE ON UPDATE CASCADE
which fails because ms_location is not in the UserDB but rather in the other database.
I don't know if Sequelize can actually handle tables spanning multiple databases servers, but I doubt it. Creating a query that spans two tables in the same database is easy, Sequelize can just create a join. It's a totally different story if the tables are on two different servers; now Sequelize would have to run two different queries and do all the join logic in memory. That's a pretty big lift.
Some databases have a way to create a table in one database that replicates or forwards to a table in another database. If PostgreSQL supports that, you could try using that to replicate or shadow the MariaDB table, which would enable Sequelize to see all the tables as being part of UserDB.