Elasticsearch partial update vs full update?

Question

Question: I've got an application where a change to a document should always get persisted into ElasticSearch only after it's validated against the full document. So I always have to retrieve the full document! Is partial update better then full update in regards to performance are there any other benefits ?

Elasticsearch documentation for partial update mentions that documents are immutable and that internally partial updates like full update reindex the full document.

Externally, it appears as though we are partially updating a document in place. Internally, however, the update API simply manages the same retrieve-change-reindex process

The documentation also mentions the following which I assume is "benefit of partial update over full update" but I don't understand. If there is a document in shard A and I do a full update on it or partial update that is in total one request. What does multiple request mean here ?

The difference is that this process happens within a shard, thus avoiding the network overhead of multiple requests

Answer 1

As you mentioned above both partial update and full update use retrieve-change-reindex process to make updation.

But the difference is : Partial Update which uses update API achieves retrieve-change-reindex through a single client request, while full update which uses index API requires separate get and index requests , and that's why full update has network overhead of multiple requests.