How does Elasticsearch search on multiple fields in the same query?

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Hey, I have a decent enough idea of how various indexes work in SQL, how multicolumn index data structures are laid out, and how Postgres can use multiple different indexes by using each individually then doing bitmap operations.

I would like to develop more of an understanding of analogous concepts in Elasticsearch. I can find plenty of resources on how an inverted index, tokenization, etc work in isolation. How does Elasticsearch search on multiple fields at once, though?

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Welcome to our community! :smiley:

What is Elasticsearch? | Elasticsearch Guide [7.15] | Elastic is a good, general place to start on this topic.

However, by default you usually just query a single field in Elasticsearch, using this approach Search your data | Elasticsearch Guide [7.15] | Elastic. You can use Multi-match query | Elasticsearch Guide [7.15] | Elastic to query multiple fields.

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Here’s some details on recent optimisations Faster Retrieval of Top Hits in Elasticsearch with Block-Max WAND | Elastic Blog