Couchbase, one startup selling commercially supported NoSQL database software, will be introducing to its subscription database this summer a new tool for querying that’s compatible with the widely used SQL query language.

For more than a year, the system has been available in developer previews, under the name N1QL, but this summer, it will ship as part of Couchbase Server under the name SQL for Documents, Couchbase president and chief executive Bob Wiederhold told VentureBeat in an interview.

“It will allow you to do joins, and that’s huge,” Wiederhold said.

Wiederhold sees the feature as a differentiator in the context of other NoSQL startups, including MongoDB, which pushes the MongoDB open-source document database. DataStax, with its Cassandra open-source columnar database, points to the Cassandra Query Language, which is similar to SQL, but it’s “not SQL-based,” Wiederhold said.

It’s interesting to see SQL query languages — historically a feature of relational databases — becoming a standard. The trend suggests that database companies are looking to expand their relevance beyond developers who build applications and need to store and serve up data. Many business analysts know SQL well and could end up feeling comfortable enough to run queries on data in Couchbase.

And Couchbase does actually want to become a bigger part of companies’ IT infrastructures. The startup today is announcing that version 4.0 of Couchbase Server, when it hits the streets this summer, will be able to perform “Multi-Dimensional Scaling.” That is, developers will be able to direct the database to build database indices and run queries on fewer servers, instead of spanning out across many of them.

“As a result, you’re going to get dramatically higher performance for indexing and querying,” Wiederhold said.

The new functionality could mean Couchbase will be able to handle more types of workloads for companies, leading to more revenue.

No wonder why Wiederhold thinks his company could post a “bigger and bigger threat to relational players.”