# Cognica

> A transactional, PostgreSQL-compatible database engine that unifies SQL, full-text search, vector search, and graph queries in a single system.

Cognica unifies relational SQL, full-text search, vector similarity, and graph queries on one mathematical framework: every query paradigm compiles to the same algebraic structure — posting lists with Boolean operations — with no bolted-on adapters and no separate engines. The site is bilingual: English pages live under `/en/` and Korean equivalents under `/ko/` (for example, `https://www.cognica.io/ko/engine`).

## Navigation

- [Home](https://www.cognica.io/en): Overview of the unified database engine, core capabilities, and live statistics.
- [Engine](https://www.cognica.io/en/engine): The Cognica engine — a transactional, unified database engine built on posting list algebra, where SQL, full-text, vector, and graph queries all compile to the same algebraic structure.
- [Research](https://www.cognica.io/en/research): Published research papers on unified query algebra, Bayesian scoring, and neural computation.
- [Demo](https://www.cognica.io/en/demo): Interactive demos of Cognica's unified search and question-answering over real-world datasets.
- [Blog](https://www.cognica.io/en/blog): Engineering and research articles on database internals, search, JIT compilation, vector scoring, and hybrid retrieval.
- [Docs](https://www.cognica.io/en/docs): Product documentation hub — SQL reference, external virtual tables, user and permission management, the C API, and the Cognica Database Internals book.
- [Contact](https://www.cognica.io/en/contact): Contact the Cognica team for product inquiries, demos, and support.
- [About](https://www.cognica.io/en/about): About Cognica — a research-driven database engine company.

## Documentation

- [Cognica Database Internals](https://www.cognica.io/en/docs/cognica-internals): A book on the engine's internals — foundations, storage engine, query processing, graph processing, execution engine, similarity search and ranking, distributed systems, and system integration.
- [SQL Reference](https://www.cognica.io/en/docs/sql-reference): SQL language reference — statements, database objects, search and analytics, programmability, and data federation.
- [External Virtual Tables](https://www.cognica.io/en/docs/external-virtual-tables): Querying external data sources as virtual tables — overview, configuration, operations, and reference.
- [User & Permission Management](https://www.cognica.io/en/docs/user-and-permission-management): Roles and membership, privileges, and system and authentication.
- [libcognica-database C API](https://www.cognica.io/en/docs/libcognica-database-c-api): The C API for libcognica-database — database and connection handling, SQL execution, cursors and transactions, and document and bulk insert.

## Optional

- [Full documentation text](https://www.cognica.io/llms-full.txt): The complete text of Cognica's product documentation in a single file — SQL reference, external virtual tables, user and permission management, the C API, and the Cognica Database Internals book.
- [GitHub](https://github.com/cognica-io): Cognica on GitHub.
- [Korean site](https://www.cognica.io/ko): Korean-language version of cognica.io.