Adding as many data sources as you need is good, inter-connecting them together is better.
The relation mechanism allows you to add a relation between different data sources, regardless of their type.
const { createAgent } = require('@forestadmin/agent');
const { createSqlDataSource } = require('@forestadmin/datasource-sql');
const { createMongooseDataSource } = require('@forestadmin/datasource-mongoose');
// Plug multiple datasources to a single agent.
const agent = createAgent(options)
.addDataSource(createSqlDataSource('postgres://user:pass@a.server:5432/mySchema'))
.addDataSource(createSqlDataSource('postgres://user:pass@another.server:5432/anotherSchema'))
.addDataSource(createMongooseDataSource(require('./mongoose-models')));
// Add a relation between a Mongoose collection and a SQL collection.
agent.customizeCollection('countryFromMongoose', collection =>
collection.addOneToManyRelation('towns', 'townsFromPostgres', {
originKey: 'country_id',
}),
);