Vector database explained

A vector database, vector store or vector search engine is a database that stores and retrieves embeddings of data in vector space. Vector databases typically implement approximate nearest neighbor algorithms so users can search for records semantically similar to a given input, unlike traditional databases which primarily look up records by exact match.[1] [2] Use-cases for vector databases include similarity search, semantic search, multi-modal search, recommendations engines, object detection, and retrieval-augmented generation (RAG).

Vector embeddings are mathematical representations of data in a high-dimensional space. In this space, each dimension corresponds to a feature of the data, with the number of dimensions ranging from a few hundred to tens of thousands, depending on the complexity of the data being represented. Each data item is represented by one vector in this space. Words, phrases, or entire documents, as well as images, audio, and other types of data, can all be vectorized.[3]

These feature vectors may be computed from the raw data using machine learning methods such as feature extraction algorithms, word embeddings[4] or deep learning networks. The goal is that semantically similar data items receive feature vectors close to each other.

Techniques

The most important techniques for similarity search on high-dimensional vectors include:

and combinations of these techniques.

In recent benchmarks, HNSW-based implementations have been among the best performers.[5] Conferences such as the International Conference on Similarity Search and Applications (SISAP)[6] and the Conference on Neural Information Processing Systems (NeurIPS)[7] have hosted competitions on vector search in large databases.

Applications

Vector databases are used in a wide range of machine learning applications including similarity search, semantic search, multi-modal search, recommendations engines, object detection, and retrieval-augmented generation.

Retrieval-augmented generation

See main article: Retrieval-augmented generation. An especially common use-case for vector databases is in retrieval-augmented generation (RAG), a method to improve domain-specific responses of large language models. The retrieval component of a RAG can be any search system, but is most often implemented as a vector database. Text documents describing the domain of interest are collected, and for each document or document section, a feature vector (known as an "embedding") is computed, typically using a deep learning network, and stored in a vector database along with a link to the document. Given a user prompt, the feature vector of the prompt is computed, and the database is queried to retrieve the most relevant documents. These are then automatically added into the context window of the large language model, and the large language model proceeds to create a response to the prompt given this context.[8]

Implementations

Name License
Aerospike[9] [10] Proprietary
AllegroGraph[11] [12] Proprietary (Managed Service)
AlloyDB AI[13] Proprietary (Managed Service)
Apache Cassandra[14] [15] Apache License 2.0
Azure Cosmos DB[16] Proprietary (Managed Service)
Chroma[17] [18] Apache License 2.0[19]
ClickHouse[20] Apache License 2.0
Couchbase[21] [22] BSL 1.1[23]
CrateDB[24] Apache License 2.0
DataStax[25] Proprietary (Managed Service)
Elasticsearch[26] Server Side Public License, Elastic License[27]
JaguarDB[28] [29] Proprietary
LanceDB[30] [31] Apache License 2.0[32]
LlamaIndex[33] MIT License[34]
MariaDB[35] [36] GPL v2[37]
Marqo[38] Apache License 2.0
Meilisearch[39] [40] MIT License[41]
Milvus[42] Apache License 2.0[43]
MongoDB Atlas[44] Server Side Public License (Managed service)
MyScaleDB[45] Apache License 2.0
Neo4j[46] [47] GPL v3 (Community Edition)[48]
ObjectBox[49] Apache License 2.0[50]
OpenSearch[51] Apache License 2.0[52]
Oracle Database[53] Proprietary (Managed Service or License)
Pinecone[54] Proprietary (Managed Service)
Pixeltable (Incremental Embedding)[55] Apache License 2.0
Postgres with pgvector[56] PostgreSQL License[57]
Qdrant[58] Apache License 2.0[59]
Redis Stack[60] [61] Redis Source Available License [62]
ScyllaDB[63] [64] Proprietary Source Available
Snowflake[65] Proprietary (Managed Service)
SurrealDB[66] BSL 1.1[67]
TiDB[68]
Typesense[69] GPL v3 (Community Edition)[70]
Vespa[71] Apache License 2.0[72]
WeaviateBSD 3-Clause[73]
YDB[74] [75] Apache License 2.0[76]

External links

Notes and References

  1. Web site: Roie Schwaber-Cohen . What is a Vector Database & How Does it Work . 18 November 2023 . Pinecone.
  2. Web site: What is a vector database . 18 November 2023 . Elastic.
  3. Web site: 2023-12-26 . Vector database . 2024-01-11 . learn.microsoft.com .
  4. Web site: Evan Chaki . 2023-07-31 . What is a vector database? . Microsoft . A vector database is a type of database that stores data as high-dimensional vectors, which are mathematical representations of features or attributes..
  5. Book: Aumüller . Martin . Bernhardsson . Erik . Faithfull . Alexander . ANN-Benchmarks: A Benchmarking Tool for Approximate Nearest Neighbor Algorithms . Lecture Notes in Computer Science . 2017 . 10609 . Beecks . Christian . Borutta . Felix . Kröger . Peer . Seidl . Thomas . Similarity Search and Applications . https://link.springer.com/chapter/10.1007/978-3-319-68474-1_3 . en . Cham . Springer International Publishing . 34–49 . 10.1007/978-3-319-68474-1_3 . 978-3-319-68474-1. 1807.05614 .
  6. Web site: Task description and call for participation SISAP 2025 Indexing Challenge . 2026-01-01 . sisap-challenges.github.io.
  7. Web site: NeurIPS Competition Practical Vector Search (Big ANN) Challenge 2023 . 2026-01-01 . neurips.cc.
  8. Lewis . Patrick . Perez . Ethan . Piktus . Aleksandra . Petroni . Fabio . Karpukhin . Vladimir . Goyal . Naman . Küttler . Heinrich . Retrieval-augmented generation for knowledge-intensive NLP tasks . Advances in Neural Information Processing Systems 33 . 2020 . 9459–9474. 2005.11401 .
  9. Web site: 2024-05-07 . Aerospike Recognized by Independent Research Firm Among Notable Vendors in Vector Databases Report. 2024-08-01 . Morningstar . en-US.
  10. Web site: 2024-04-04 . Aerospike raises $109M for its real-time database platform to capitalize on the AI boom. 2024-08-01 . TechCrunch . en-US.
  11. Web site: 2023-12-29 . AllegroGraph 8.0 Incorporates Neuro-Symbolic AI, a Pathway to AGI. 2024-06-06 . TheNewStack . en-US.
  12. Web site: 2024-01-18 . Franz Inc. Introduces AllegroGraph Cloud: A Managed Service for Neuro-Symbolic AI Knowledge Graphs. 2024-06-06 . Datanami . en-US.
  13. Web site: Wiggers . Kyle . 2023-08-29 . Google's AlloyDB AI transforms databases to power generative AI apps . 2026-01-01 . TechCrunch . en-US.
  14. Web site: 2023-09-22 . 5 Hard Problems in Vector Search, and How Cassandra Solves Them. 2023-09-22 . TheNewStack . en-US.
  15. Web site: Vector Search quickstart. 2023-11-21 .
  16. Web site: 26 December 2023 . Vector database . 2024-01-10 . learn.microsoft.com.
  17. Web site: Palazzolo . Stephanie . Vector database Chroma scored $18 million in seed funding at a $75 million valuation. Here's why its technology is key to helping generative AI startups. . 2023-11-16 . Business Insider . en-US.
  18. Web site: MSV . Janakiram . 2023-07-28 . Exploring Chroma: The Open Source Vector Database for LLMs . 2023-11-16 . The New Stack . en-US.
  19. Web site: chroma/LICENSE at main · chroma-core/chroma . GitHub . en.
  20. News: 2023-10-26 . Can you use ClickHouse for vector search? ClickHouse Docs . https://web.archive.org/web/20250622222726/https://clickhouse.com/docs/knowledgebase/vector-search . 2025-06-22 . 2025-07-02 . en . live .
  21. Web site: 2023-08-30 . Couchbase aims to boost developer database productivity with Capella IQ AI tool . VentureBeat . en-US.
  22. Web site: 2023-12-06 . Investor Presentation Third Quarter Fiscal 2024 . Couchbase Investor Relations . en-US.
  23. Web site: Anderson . Scott . 2021-03-26 . Couchbase Adopts BSL License . 2024-02-14 . The Couchbase Blog . en-US.
  24. Web site: 16 November 2023 . Open Source Vector Database . 2024-11-06 . CrateDB Blog.
  25. News: Sean Michael Kerner . 18 July 2023 . DataStax brings vector database search to multicloud with Astra DB . Venture Beat.
  26. News: Kerner . Sean . 23 May 2023 . Elasticsearch Relevance Engine brings new vectors to generative AI . 18 November 2023 . VentureBeat.
  27. Web site: elasticsearch/LICENSE.txt at main · elastic/elasticsearch . GitHub . en.
  28. Web site: JaguarDB Homepage . 2025-04-12 . JaguarDB . en-US.
  29. Web site: 2023-07-03 . Vector DBMS . 2025-04-12 . db-engines.com . en-US .
  30. Web site: 2024-12-17 . LanceDB Homepage . 2024-12-17 . LanceDB . en-US.
  31. Web site: 2025-09-22 . A scalable, elastic database and search solution for 1B+ vectors built on LanceDB and Amazon S3 AWS Architecture Blog . 2026-01-01 . aws.amazon.com.
  32. Web site: lancedb/LICENSE at main · lancedb/lancedb . 2024-12-17 . GitHub . en.
  33. Web site: Wiggers . Kyle . 2023-06-06 . LlamaIndex adds private data to large language models. 2023-10-29 . TechCrunch . en-US.
  34. Web site: llama_index/LICENSE at main · run-llama/llama_index. 2023-10-29 . GitHub . en.
  35. Web site: MariaDB Vector . 2024-07-30 . MariaDB.org . en-US.
  36. Web site: Vector search in old and modern databases . 2024-07-30 . manticoresearch.com . en-us.
  37. Web site: Licensing FAQ . 2024-07-30 . MariaDB KnowledgeBase.
  38. Web site: Sawers . Paul . 2023-08-16 . Meet Marqo, an open source vector search engine for AI applications . 2024-08-20 . TechCrunch . en-US.
  39. Web site: 2024-10-08 . Meilisearch Homepage. 2023-10-29 . Meilisearch . en-US.
  40. Web site: Compare Algolia vs ElasticSearch vs Meilisearch vs Typesense . 2026-01-01 . typesense.org . en.
  41. Web site: meilisearch/LICENSE at main · meilisearch/meilisearch. 2024-10-08 . GitHub . en.
  42. Web site: Liao . Ingrid Lunden and Rita . 2022-08-24 . Zilliz raises $60M, relocates to SF. 2023-10-29 . TechCrunch . en-US.
  43. Web site: Milvus license. GitHub.
  44. Web site: 2023-06-22 . Introducing Atlas Vector Search: Build Intelligent Applications with Semantic Search and AI Over Any Type of Data. MongoDB. en-US.
  45. Web site: Jamil . Usama . 2024-05-20 . Build an Advanced RAG Application Using MyScaleDB and LlamaIndex . 2026-01-01 . The New Stack . en-US.
  46. Web site: 2023-08-22. Neo4j enhances its graph database with vector search. itbrief. en-AU.
  47. Web site: Vector search indexes. neo4j. en-US.
  48. Web site: Neo4j Licensing.
  49. Web site: 2024-07-03. Top Fifteen Vector Databases. 2024-07-03 . db-engines.com . en-US.
  50. Web site: ObjectBox Java license. github.
  51. Web site: 2023-08-02. Using OpenSearch as a Vector Database. 2024-02-07 . OpenSearch.org . en-US.
  52. Web site: OpenSearch license. github.
  53. Web site: Hook . Doug . Priyadarshi . Ranjan . May 2, 2024 . Oracle Announces General Availability of AI Vector Search in Oracle Database 23ai . July 9, 2024 . oracle.
  54. Web site: 2023-07-14 . Pinecone leads 'explosion' in vector databases for generative AI. 2023-10-29 . VentureBeat . en-US.
  55. Web site: Automatic incremental embedding index. 2025-07-04 . Pixeltable . 24 April 2025 . en-US.
  56. Web site: pgvector. 2023-11-27 . GitHub . en-US.
  57. Web site: pgvector/License. 2023-11-27 . GitHub . en-US.
  58. Web site: Sawers . Paul . 2023-04-19 . Qdrant, an open-source vector database startup, wants to help AI developers leverage unstructured data. 2023-10-29 . TechCrunch . en-US.
  59. Web site: qdrant/LICENSE at master · qdrant/qdrant. 2023-10-29 . GitHub . en.
  60. Web site: Using Redis as a Vector Database with OpenAI OpenAI Cookbook . 2024-02-10 . cookbook.openai.com . en.
  61. Web site: Redis as a vector database quick start guide . 2024-01-31 . Redis . en . 2024-01-31 . https://web.archive.org/web/20240131205622/https://redis.io/docs/get-started/vector-database/ . dead .
  62. Web site: Search and query . 2024-02-10 . Redis . en.
  63. Web site: 2026-02-05 . Open source USearch library jumpstarts ScyllaDB vector search. 2026-02-23 . TheNewStack . en-US.
  64. Web site: 2026-01-20 . ScyllaDB adds vector search to managed database platform. 2026-02-23 . TechTarget . en-US.
  65. Web site: 2024-05-17 . Vector data type and vector similarity functions — General Availability. 2024-05-17 . Snowflake . en-US.
  66. Web site: Wiggers . Kyle . 2023-01-04 . SurrealDB raises $6M for its database-as-a-service offering. 2024-01-19 . TechCrunch . en-US.
  67. Web site: SurrealDB License FAQs The ultimate multi-model database . 2024-02-14 . SurrealDB . en.
  68. Web site: TiDB Vector Search . docs.pingcap.com .
  69. Web site: Martinez . Miguel . 2024-06-20 . Typesense Homepage. 2024-06-20 . Typesense . en-US.
  70. Web site: Typesense licensing. .
  71. Web site: Creating a Vespa Vector Database . 2026-01-01 . Capital One . en.
  72. Web site: vespa/LICENSE at master · vespa-engine/vespa. GitHub. en.
  73. Web site: weaviate/LICENSE at master · weaviate/weaviate. 2023-10-29 . GitHub . en.
  74. Web site: Langchain YDB. 2025-07-26 . Langchain . en-US.
  75. Web site: YDB - Vector Search. ydb.tech . 2025-07-26 . en-US.
  76. Web site: ydb/LICENSE at master · ydb-platform/ydb. 2025-07-26 . GitHub . en.

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