How can we ensure Data integrity in mongoDb?

Question

i am trying to migrate from relational database (mysql) data to nosql (mongoDb) . But how can i ensure data integrity in mongodb . what i have found that we cannot do it on server side. what should i use on application side to handle data integrity ?

For eg: i have two tables user and task . Both have userId field common . if i add a new entry in task table it should check if userid present in user table. this is one of the requirement others like adding constraints , updating values etc

Answer 1

Ultimately, you're screwed. There's no way (in mongodb) to guarantee data integrity in such scenario, since it's lacking relations in general and foreign keys in particular. And there's little point in building application-level checks. No matter how elaborate they are, they can still fail (hence "no guarantee").

So it's either embedding (so that related data is always there, right in the document) or abandoning the hope of consistent data.

Answer 2

• MongoDb is nosql and hence no joins.
• Data is stored as BSON documents and hence no Foreign key constraints

Steps to ensure Data Integrity:

• Check in the application before adding the task document whether it is having a valid user.