Elasticsearch - Required terms in a Lucene Query

Question

I am working on a search query against an Elasticsearch search index. Sometimes, I want to require that a term be present. To address this scenario, I've been reading about the "+" boolean operator . However, I'm slightly confused by it.

I do not understand where it fits against the AND (&&) operator and using the phrase operator ("). For example, lets say I had a search index of animals. Imagine I wanted to find foxes. How is

brown +fox different from brown && fox different from "brown" && "fox" . In my understanding, these are very similar. I understand how the last two differ. However, for the life of me, I do not understand why I would ever use the "+" operator.

Any help is appreciated.

Answer 1

for the life of me, I do not understand why I would ever use the "+" operator.

+ : this term must be present

- : this term must not be present

All other terms are optional. For example, this query:

quick brown +fox -news

states that:

• fox must be present
• news must not be present
• quick and brown are optional — their presence increases the relevance

Phrase Query :

Phrase , surrounded by double quotes —

"quick brown"

— searches for all the words in the phrase, in the same order

AND and && are both the same operators ie both must be present.

I hope it clarifies.

Reference