Updating documents in Elasticsearch - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the _update API in Elasticsearch?

The _update API allows you to change parts of a document without replacing the entire document. It updates only the specified fields.

intermediate

How do you update a document's field using a script in Elasticsearch?

You use the script parameter in the _update API to modify fields dynamically. For example, increment a counter or change a value based on current data.

intermediate

What happens if you try to update a document that does not exist in Elasticsearch?

By default, the update will fail with a 404 error. But you can use doc_as_upsert: true to create the document if it doesn't exist.

intermediate

Explain the difference between doc and upsert in an update request.

doc contains the fields to update in an existing document. upsert provides a document to insert if the original document does not exist.

beginner

Why is partial update preferred over reindexing the whole document?

Partial update changes only the needed fields, saving time and resources. Reindexing the whole document is slower and can cause more load on the system.

Which Elasticsearch API is used to modify parts of an existing document?

A _delete

B _search

C _update

D _bulk

The _update API is designed to update parts of a document without replacing it entirely.

What does setting doc_as_upsert: true do in an update request?

A Deletes the document if it exists

B Prevents any update from happening

C Updates all documents in the index

D Creates the document if it does not exist

Setting doc_as_upsert: true tells Elasticsearch to insert the document if it does not already exist.

How can you increment a numeric field in a document during update?

A Using a script in the update request

B By deleting and reindexing the document

C Using the _search API

D By changing the mapping

You can use a script in the _update API to increment numeric fields dynamically.

If you want to replace the entire document, which API should you use?

A _update

B _index

C _search

D _bulk

The _index API replaces the whole document when you provide the same ID.

What is a benefit of partial updates over full document replacement?

A Uses less network and processing resources

B Deletes the document faster

C Changes the index mapping automatically

D Prevents any data loss

Partial updates only send and change the fields needed, saving bandwidth and processing time.

Describe how to update a document in Elasticsearch using the _update API with a script.

Think about changing a field value without sending the whole document.

Explain the difference between using doc and upsert in an update request.

One updates, the other creates if missing.