Caching and search
OpenSearch
OpenSearch is an open source distributed search and analytics engine, a fork of Elasticsearch 7.10 under Apache-2.0.
What it is
OpenSearch appeared in 2021 when Elastic changed the Elasticsearch license. AWS forked Elasticsearch 7.10 and Kibana and released them as OpenSearch and OpenSearch Dashboards.
In 2024 the project moved under the OpenSearch Software Foundation within the Linux Foundation, so a neutral organization governs it, not one company.
Technically it is the same class of system: Lucene, shards, replication, a REST API. Besides search it has built-in plugins for security, SQL queries, vector and neural search. It is available as the managed Amazon OpenSearch Service.
Use it when
- You need search or log analytics under a clean Apache-2.0 license.
- You work on AWS and want a managed service.
- You want neutral project governance without dependence on one company.
Avoid it when
- You need the newest Elastic Stack features: some exist only in Elasticsearch.
- The catalog is small and lightweight Meilisearch or Typesense is enough.
Key concepts
- Index / shard
- An index is split into shards that are spread across cluster nodes.
- Query DSL
- The JSON query language: match, bool, range and others.
- OpenSearch Dashboards
- A web interface for visualization and queries, a fork of Kibana.
- k-NN / neural search
- Plugins for search by vector embeddings, similarity by meaning.
Example
Interview questions
1. Why was OpenSearch created?
After the Elasticsearch license change in 2021, AWS and the community forked version 7.10 under Apache-2.0 to keep a fully open source option.
2. Is OpenSearch compatible with Elasticsearch clients?
Versions based on 7.10 are mostly compatible. Newer Elasticsearch clients may refuse to work with OpenSearch, so prefer the official OpenSearch clients.
3. What changed in 2024?
OpenSearch was handed to the OpenSearch Software Foundation under the Linux Foundation, so governance became neutral instead of AWS-controlled.
Comparisons with this technology
Related technologies
- ElasticsearchElasticsearch is a distributed search and analytics engine built on Lucene with a REST API and JSON documents.
- MeilisearchMeilisearch is a fast search engine written in Rust with search-as-you-type, typo tolerance and simple setup.
- TypesenseTypesense is a fast C++ search engine with typo tolerance, facets and search-as-you-type that keeps its index in memory.
- ELK StackThe Elasticsearch, Logstash and Kibana set for collecting, full text searching and visualizing logs and events.
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