MongoDB has 'architectural' problems and has done nothing to improve scalability, claims Couchbase CEO

Bob Wiederhold claims acquisition of WiredTiger was only a 'small step forward' for MongoDB, and that it has merely covered up its scalability issues

Popular NoSQL database MongoDB has "architectural" problems and has done nothing to improve scalability despite its acquisition of WiredTiger, according to rival Couchbase's CEO Bob Wiederhold.

The thinly veiled dig should come as no surprise; the two companies have been going head-to-head for several years now - with both aiming to convince enterprises to use their open source products, with the hope that businesses would see the benefits of them on small-scale projects before opting to use the product for mission-critical applications, and then broadly deploying NoSQL to replace existing relational systems such as those offered by Oracle or Microsoft.

The two firms, along with DataStax have been touting their product as the best in breed of NoSQL players. There had been criticism of MongoDB's scalability by smartphone app Viber, which decided to switch to Couchbase, but MongoDB aimed to put that right by acquiring WiredTiger last December.

This June, MongoDB revealed the results of tests using the Yahoo Cloud Serving Benchmark (YCSB) at MongoDB World. The tests found that its latest version, 3.0.1 with WiredTiger, was ahead of both Couchbase and DataStax's Cassandra for scalability.

But Couchbase immediately responded by claiming that benchmarks carried out by independent firm Avalon LLC found that Couchbase Server outperforms both Cassandra and MongoDB with WiredTiger, and Wiederhold claimed that the acquisition of WiredTiger meant that MongoDB had taken "a small step forward", and that the "differentiation between our products hasn't changed in any meaningful way".

He suggested that MongoDB still has scalability issues, even with WiredTiger, and that this was caused by architectural issues.

"We have had a lot of customers that started out at Mongo that switched to Couchbase, and DataStax have had a lot of customers who have switched from Mongo to Cassandra because of scalability and performance," he said.

"So far they have done one thing, which is to buy WiredTiger - that's still not their default storage engine - that's a very critical piece. Their scalability problems are a different set of problems that they have done nothing I am aware of to fix," he added.

Wiederhold said any changes that Mongo has made to its product are merely "cosmetic".

"What they've done is set up an administrative console and provided some admin operational things to try and hide some of their complexities and problems," he claims.

Wiederhold did admit that MongoDB was by far the most popular NoSQL solution, but put this down to developers who used the product during the weekend at home, and for lightweight solutions in the workplace.

He said that MongoDB had "hit a wall" when it came to providing a solution for mission-critical applications.

"[When it came to using NoSQL for mission-critical applications] the criteria for success changed dramatically - you had to have scalability and performance and that's why Couchbase took off and why Mongo really hit a wall. Their growth dramatically slowed, they had massive changes in their management," he said.

Mat Keep, director of the product team, at MongoDB, responded to Wiederhold's claims by stating that the firm "lets its customers speak for themselves".

"Yesterday at the Code Enterprise event in New York, Goldman Sach's CIO said: ‘Don't try to sell me database software. We're very happy with MongoDB'," he said.

Keep added that in the last two weeks the firm has added customers including Urban Outfitters, YouGov, Sprinklr and Hekima to the firm's client base.

Read the full interview with Couchbase CEO Bob Wiederhold here.