add child document without existing parent doc in elastic search

Question

When I index a child document without an existing parent document (I am passing random parent id) it works without error and indexes child document. I expect it to give an error so I could check whether parent doc exist or not. How will I prevent it to be indexed without proper parent document?

Answer 1

It's how ElasticSearch actually works (as far as undestand it). It doesn't have reference constaints. ElasticSearch is not an RDBMS that makes a huge focus on a referential integrity. ES makes focus on the performace, availability, etc - the kind of things for which you have to sacrifice integraty to some extent, as ensuring integraty is in most cases a costly thing. ES is often seen (and sometimes actually used) as an object-oriented NoSQL data source. And for NoSQL DBs lacking of referencial integraty is a common thing.

You can read more about this for example here - https://www.found.no/foundation/elasticsearch-as-nosql/

Most relational databases also let you specify constraints to define what is and isn’t consistent. For example, referential integrity and uniqueness can be enforced. You can require that the sum of account movements must be positive and so on. Document oriented databases tend not to do this, and Elasticsearch is no different.