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Elasticsearch

In-depth entry

by Elastic N.V. · Database · also known as Elastic Stack, ELK

Distributed search and analytics engine on Apache Lucene with full-text, aggregations, vector search and ES|QL; triple-licensed AGPL, SSPL and Elastic License

AGPL-3.0-only OR SSPL-1.0 OR Elastic-2.0 licenseOpen sourceFreeUsage-basedEnterpriseSelf-hostedCloudSelf-hostable
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Link verified Nov 2, 2026

Overview

Elasticsearch is a distributed search and analytics engine developed by Elastic N.V. on top of Apache Lucene. Documents are stored as JSON in indices split into shards and replicated across a cluster; queries combine full-text relevance, structured filters, aggregations for analytics, geospatial search and dense-vector kNN search for embeddings. ES|QL offers a piped query language alongside the JSON Query DSL, ingest pipelines transform data on the way in, and Kibana supplies dashboards, alerting and management. Elasticsearch underpins log and observability stacks, site search and, increasingly, hybrid lexical-plus-vector retrieval for RAG.

Licensing deserves care. Since 2024 the default source license is a triple license: the GNU Affero General Public License v3.0 only, the Server Side Public License v1, or the Elastic License 2.0, at the user's choice; code in the x-pack directory is available solely under Elastic License 2.0, and some files remain Apache 2.0. Prebuilt distributions ship with the free Basic tier plus paid Platinum and Enterprise features, and Elastic Cloud provides hosted and serverless deployments.

It runs on the JVM and expects careful heap and shard sizing; cluster operations, mapping design and upgrades take expertise. Relational joins are limited, and commercial features such as advanced security, machine learning jobs and some vector-search conveniences sit behind subscription tiers.

Capabilities

  • Full-text search with BM25 relevance and analyzers
  • Aggregations for analytics over structured and time-series data
  • Dense-vector kNN and hybrid retrieval
  • ES|QL and JSON Query DSL
  • Ingest pipelines and index lifecycle management
  • Sharding and replication across a cluster
  • Kibana dashboards and alerting
  • Clients for Java, Python, JavaScript, Go, .NET, PHP, Ruby and Rust

Typical workflows

  1. Centralized log and observability search with Kibana
  2. Site or catalog search with relevance tuning
  3. Hybrid keyword and vector retrieval for RAG
  4. Security analytics (SIEM) on the Elastic Stack

Strengths

  • Mature, widely deployed engine with a large ecosystem
  • Search, analytics and vectors in one system
  • AGPL option restores an OSI-approved license choice
  • Hosted and serverless options on Elastic Cloud

Limitations

  • Three-way license plus ELv2-only x-pack code requires review
  • JVM heap and shard sizing demand operational expertise
  • Limited joins and transactions
  • Several features gated behind paid subscription tiers

Prerequisites

  • JVM-based server or container, or an Elastic Cloud deployment

Who it is for

  • Platform and observability teams
  • Search engineers
  • Developers adding hybrid retrieval

Alternatives & comparison

OpenSearch is the Apache-2.0 fork created after Elastic's 2021 license change and now governed by the OpenSearch Software Foundation; the two share ancestry but APIs and features have diverged. Meilisearch and Typesense are single-node engines focused on application search rather than analytics. ClickHouse covers the log-analytics use case with SQL and columnar storage instead of inverted indexes. Qdrant and other vector databases specialize in embedding search without full-text analytics.

  • ClickHouse

    Open-source columnar OLAP database server for fast aggregations over billions of rows, with MergeTree storage, SQL and a managed ClickHouse Cloud

    Open sourceOpen source
  • Meilisearch

    Rust search engine for application search-as-you-type with typo tolerance, faceting and hybrid semantic search; MIT core plus BSL enterprise parts

    MixedOpen source
  • Milvus

    Open-source vector database from Zilliz with Lite, Standalone and Distributed deployments, many index types and GPU acceleration

    Open sourceOpen source
  • MongoDB

    Document database storing BSON documents with a rich aggregation pipeline, available as a source-available Community Server or the managed Atlas service

    Source-availableFree
  • OpenSearch

    Apache-2.0 search and analytics suite forked from Elasticsearch and Kibana, governed by the OpenSearch Software Foundation

    Open sourceOpen source
  • pgvector

    PostgreSQL extension adding vector types, distance operators and HNSW/IVFFlat indexes for similarity search inside the database

    Open sourceOpen source
  • Qdrant

    Open-source vector search engine written in Rust with filterable HNSW indexes, sparse and multi-vector support, REST/gRPC APIs and a managed cloud

    Open sourceOpen source
  • Typesense

    GPL-licensed in-memory search engine in C++ offering typo-tolerant instant search, faceting, vector and hybrid search, with Typesense Cloud hosting

    Open sourceOpen source
Compare Elasticsearch with its alternatives →

Sources & verification

Primary sources consulted for this record. Claims are tied to the fields each source supports; the automated link checker re-verifies every URL on a schedule.

  • License
    Elasticsearch LICENSE.txt

    https://github.com/elastic/elasticsearch/blob/main/LICENSE.txt

    Supports: license_spdx, source_model

    Default triple license AGPL-3.0-only / SSPL-1.0 / Elastic-2.0; x-pack solely Elastic-2.0; some files Apache-2.0

    checked Nov 1, 2026
  • License
    Elastic License 2.0

    https://www.elastic.co/licensing/elastic-license

    Supports: license_spdx

    checked Nov 1, 2026
  • Official documentation
    Elastic Docs

    https://www.elastic.co/docs

    Supports: capabilities, languages

    checked Nov 1, 2026
  • Official site
    Elasticsearch | Elastic

    https://www.elastic.co/elasticsearch

    Supports: name, summary

    checked Nov 1, 2026
  • Pricing page
    Elastic pricing

    https://www.elastic.co/pricing

    Supports: pricing_model

    checked Nov 1, 2026
  • Repository
    elastic/elasticsearch

    https://github.com/elastic/elasticsearch

    Supports: repo_url

    checked Nov 1, 2026
Confidence
High
Reviewed
Nov 1, 2026
Links
Verified · Nov 2, 2026

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pgvector

Andrew Kane (pgvector project) · Vector databases

In-depth entry

PostgreSQL extension adding vector types, distance operators and HNSW/IVFFlat indexes for similarity search inside the database

PostgreSQLOpen sourceFreeSelf-hostedNov 2, 2026

Weaviate

Weaviate B.V. · Vector databases

Open-source vector database in Go with pluggable vectorizer modules, hybrid BM25 and vector search, multi-tenancy and a managed cloud

BSD-3-ClauseOpen sourceFreemiumSelf-hostedBroken

Chroma

Chroma · Vector databases

Open-source embedding database with a minimal Python and JavaScript API, usable in-process, as a server or through Chroma Cloud

Apache-2.0Open sourceUsage-basedLocalSelf-hostedNov 2, 2026

Pinecone

Pinecone Systems, Inc. · Vector databases

Fully managed, proprietary vector database service with serverless indexes, namespaces, metadata filtering and integrated embedding and reranking

ProprietaryFreemiumUsage-basedNov 2, 2026

Milvus

Zilliz / LF AI & Data Foundation · Vector databases

Open-source vector database from Zilliz with Lite, Standalone and Distributed deployments, many index types and GPU acceleration

Apache-2.0Open sourceFreeLocalSelf-hostedNov 2, 2026