Sep 16, 2024 · Backend Development

Understanding Elasticsearch’s Document Retrieval Process

The article walks through Elasticsearch’s document retrieval workflow, covering single‑document GET, multi‑document mget, the two‑stage query_then_fetch mechanism, shard routing, load balancing, query and fetch phases, collectors, rescore, and pagination optimizations.

Document RetrievalElasticsearchQuery_then_fetch

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Understanding Elasticsearch’s Document Retrieval Process

System Architect Go

Nov 17, 2020 · Big Data

Elasticsearch Distributed Search Mechanisms: query_then_fetch and dfs_query_then_fetch

Elasticsearch provides two search types—query_then_fetch (default) and dfs_query_then_fetch—each involving a multi-step process where the client node distributes queries to relevant shards, shards execute searches using local or global term frequencies, aggregate results, and retrieve full documents, with noted trade‑offs.

ElasticsearchQuery_then_fetchdfs_query_then_fetch

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