Cloud databases may be to blame for NoSQL’s stalled momentum in 2016, but they may be seeing their own growth level off a bit. Using DB-Engines’ database popularity rankings, which amalgamate a range of datasets including Stack Overflow mentions and job postings, it’s clear that cloud databases keep leaping toward the world’s top-25 most popular databases (Amazon’s DynamoDB has already made it). It’s also clear, however, that they’re no longer getting there quite as fast.

This doesn’t suggest we’re anywhere near the apex of cloud database adoption, but rather that developers may not be ready to fully give their infrastructure and data to the cloud providers.

Slow and steady

Reading the DB-Engines tea leaves, it’s clear that cloud databases keep growing. How much? Try 10X over the last four years:

That’s the good news.

SEE Want to avoid cloud lock-in? It’s about the database (TechRepublic)

To get at the bad news, it’s helpful to review how DB-Engines compiles its data:

We calculate the popularity value of a system by standardizing and averaging of the individual parameters. These mathematical transformations are made in a way so that the distance of the individual systems is preserved. That means, when system A has twice as large a value in the DB-Engines Ranking as system B, then it is twice as popular when averaged over the individual evaluation criteria. In order to eliminate effects caused by changing quantities of the data sources themselves, the popularity score is always a relative value, which should be interpreted in comparison with other systems only.

With this “relative ranking” in mind, it’s notable that cloud databases aren’t making as much headway against the established leaders as one might expect, given the popularity of AWS, Microsoft Azure, and Google Cloud.

It’s all relative

Amazon’s DynamoDB (ranked no. 22, up from no. 26 in March 2016), for example, is just 10% as popular as MongoDB (no. 5), and grew its relative popularity score roughly one-third as fast as MongoDB over the past year. Microsoft Azure DocumentDB (no. 56, up from no. 77), for its part, is just 3% as popular as Apache Cassandra (no. 8), though DocumentDB did grow slowly over the past year while Cassandra’s score dropped a bit (relatively speaking).

And, if we compare any of these cloudy upstarts to two stodgy relational database peers, Microsoft SQL Server or Postgres, they all were a rounding error in terms of relative growth by comparison. For example, Amazon’s Aurora, one of the fastest-growing services in AWS history, jumped just 1.93 points in the DB-Engines calculus…while Postgres exploded by 58.01 points in 2016.

SEE Why cloud databases threaten Oracle’s lead in the enterprise (TechRepublic)

Again, this isn’t to suggest that the cloud database has lost permanent steam. The 10X increase in popularity over four years belies that notion.

Rather, it’s probably indicative of developers pausing on their cloud database commitments, relative to more traditional databases, as a way to keep some flexibility. As database executive Kelly Stirman told me, “The database is the most important tech decision” for avoiding lock-in. Companies are piling into the public clouds for infrastructure needs as a way to increase flexibility and productivity, and may be holding back on cloud databases for the very same reason.