What is Database of Databases (dbdb.io)?

dbdb.io is the Database of Databases, a curated reference guide to implementations of database systems, maintained by Carnegie Mellon University and described as "the encyclopedia of database systems." It is useful when you need a structured overview of a database product, want to compare systems by data model, or are looking for a starting point for research or tool selection. Entries are reference material rather than vendor documentation, so treat them as orientation, not as the final word on a product's current features.

What you can find on the site

The site organizes database systems into browsable entries and aggregate views:

• Individual entries for database systems, such as the featured entry on Amazon Redshift, which is described as a data warehouse product and part of Amazon Web Services, a relational DBMS designed specifically for that purpose, proprietary, OLAP, and in existence since 2012.
• Browse by data model, with counts of systems per model.
• Leaderboards, updated daily, tracking activity and interest.
• Thematic collections, such as databases named "Store," Wisconsin database systems, and databases controlled by the Apache Software Foundation.

Browse by data model

Data model is the primary organizing dimension. The site lists 14 models with the following counts:

Use this view when your constraint is the data model itself — for example, when you need a graph or vector store and want to see what exists in that category before narrowing by other criteria.

Leaderboards and what they measure

The leaderboards are updated daily and cover different signals, so read the label before drawing conclusions:

• Most Recent — newly modified entries, with a relative timestamp. Examples: OrioleDB (Relational, 3d ago), Turso (Relational, 3d ago), Xodus (Document / XML, 9d ago), voidDB (Key-Value, 9d ago), CnosDB (Relational, 10d ago).
• Most Viewed (last 30 days) — includes a percentage change, e.g. Oracle (Key-Value, Graph, Triplestore / RDF, Document / XML, Relational, −26%), Derby (Relational, −20%), Heroic (Key-Value, −48%), DynamoDB (Document / XML, Key-Value, −45%), TileDB (Array / Matrix, −1%).
• Most Edited (last 30 days) — edit counts, e.g. SereneDB (Relational, 2), CloverDB (Document / XML, 1), CnosDB (Relational, 1), ConceptBase.cc (Object-Oriented, 1), Dremio (Relational, 1).

"Most viewed" reflects attention, not quality or adoption; a falling percentage means fewer views than the prior period, not that a system is declining in use. "Most edited" reflects wiki activity, which often tracks how actively a community maintains its entry.

Who it is for

• Developers choosing or evaluating a database who want a model-first index and a quick factual summary.
• Students learning how database systems are classified and what categories exist.
• Researchers needing a citable overview of systems and their attributes.

How to use it in practice

1. Start from Browse by Data Model if your requirement is architectural, or from an entry directly if you already have a product in mind.
2. Open the entry and check the attributes it records — for example, Redshift's entry notes vendor, category, licensing, and year.
3. Cross-check anything decision-critical against the vendor's own documentation, since entries are reference summaries and may lag a product's current state.
4. Use the leaderboards to discover systems you did not know about, then evaluate them on their own entries.

Limitations to keep in mind

The site is an encyclopedia, not a benchmark or a buyer's guide. It does not publish pricing, performance results, or support commitments, and the counts and rankings reflect catalog contents and site activity rather than market share. For a purchase or migration decision, use dbdb.io to build your shortlist, then verify capabilities, licensing, and cost with the vendor.