PostgreSQL is a free, object-relational database management system (ORDBMS) emphasizing extensibility and SQL compliance.

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In order to focus on one technology, PostgreSQL has been preferred as the default database system for new use cases since 2024. This applies to our in-house developments as well as the IT infrastructure requirements for the procurement of specialist applications. With PostgreSQL, we use a stable and established database system that, above all, allows us to be vendor-independent. Other database systems can only be used in technically justified exceptions.

Together with MariaDB, which is also free, around 40% of our database instances currently use an open source database system.

With the open-source extension pgvector, PostgreSQL additionally gains vector similarity search: vector types, HNSW/IVFFlat indexes and distance operators over embeddings are added directly in the database — so a separate vector database can be avoided for many workloads. We use pgvector in RIS-KI, which stores the embeddings of council documents directly alongside its relational data in the official pgvector container image. The Dienstleistungsfinder KI-Suche uses the dedicated vector database Qdrant for its hybrid search; Zammad-AI uses Qdrant for retrieval.