Although the DB-Engines Ranking does not measure the number of installations of the systems, or their use within IT systems, they claim that an increase in popularity can precede a corresponding increase in usage of the system and therefore the DB-Engines Ranking can act as an early indicator.
The DB-Engines Ranking scores DBMS based on a variety of different metrics:
2. Frequency of technical discussions about the system – using the number of related questions and the number of interested users on the well-known IT-related Q&A sites such as Stack Overflow and DBA Stack Exchange.
4. Number of profiles in professional networks, in which the system is mentioned – LinkedIn is used for this metric.
5. Relevance in social networks – For this measurement the number of Twitter tweets in which the system is mentioned is calculated. Visit the DB-Engines site to view the complete leaderboard and find out more about their methodology.