OpenSearch vs. Elasticsearch: A Fork in the Road

OpenSearch and Elasticsearch are compared across features, licensing, and community support. Both originated from the same Elasticsearch 7.10.2 codebase after Amazon forked Elasticsearch in 2019 following a licensing dispute. OpenSearch uses the permissive Apache 2.0 license while Elasticsearch uses SSPL and Elastic License with some commercial-only features. Elasticsearch has a larger community, but OpenSearch is growing. Key decision factors include feature requirements, budget, and community needs. Both share common operational challenges around cost, stability, and data retention at scale, with columnar databases like ClickHouse presented as an alternative backend.