DB-Engines, a site that uses a combination of metrics to track various database technologies, recently crowned Oracle most popular among the 290 databases it follows. But the reasons for its popularity in DB-Engines' ranking are perhaps not so obvious.
DB-Engines uses several different metrics to compute popularity. Rather than attempt to measure how many actual installations there are of any given database (nearly impossible to accomplish), the site aggregates metrics such as mentions in Google Trends, the number of job listings that mention the product, Stack Overflow and Stack Exchange discussions, tweets, LinkedIn profile appearances, and so on. In that sense, it's much like the Tiobe index, which ranks programming languages by discussion frequency rather than usage metrics.
For the second year running, DB-Engines ranked Oracle at the top, with MySQL and Microsoft SQL Server following extremely closely in second and third position. The other major contenders -- PostgreSQL, MongoDB, and IBM DB2 -- scored one-third or less of the top three's ratings on DB-Engines' logarithmic scale.
On the face of it, Oracle ranks highly because it is in wide use among companies, meaning expertise in Oracle products -- and discussions about how to get the most out of them -- remain in demand.
However, DB-Engines doesn't provide any kind of sentiment analysis to measure whether discussions are positive or negative and how many of them revolve around migrating from Oracle to competing solutions -- be they other RDBMSes or one of the rising crowd of NoSQL solutions. (A major reason companies don't migrate away from Oracle is because of that company's contractual arrangements with customers, rather than for any actual technical reason.)
One big database of note making gains in DB-Engines's scoring system is MongoDB. The NoSQL document store database has reached out to enterprises over the past year with new in-memory processing, encryption, and connectors to third-party BI products. But given the newness of those features, they can't be solely responsible for MongoDB's rise in popularity; in fact, DB-Engines has been tracking a rise in interest in the product since 2013.
Other open source databases that constitute a threat to Oracle also showed gains. PostgreSQL, often mentioned as a possible Oracle replacement, has gained steadily since early 2014.
If Oracle's popularity is mainly down to its existing user base, the company shows every intention of keeping those customers close and has been offering new cloud-based services, new Sparc hardware designed to run its products faster, and the possibility of a perpetual licensing scheme as part of that push.
This last move is a sign that the company is under pressure since its licensing remains highly complex, and Oracle's revenue stream has shifted from attracting new customers to extracting money from existing ones (either through licensing arrangements or by switching those customers to cloud services).