NoSQL's flexibility makes database technology ideal for start ups. Taxi app Hailo chose the NoSQL database Cassandra because it "makes it easy to do global distribution and it has high availably characteristics", says Dave Gardner, architect at the firm. Cassandra was also the best way for the fast-growing company to scale.
"We wanted to expand globally, and we wanted people to be able to use one app," Gardner says. "We wanted people to fly from the UK to New York and get off the plane and hail a cab. People trust us to be there and to work; we didn't want maintenance windows or downtime due to data centre outages."
Hailo still uses MySQL, but is planning to move its entire app based storage requirement to Cassandra in long term. Hailo will retain relational databases for any information it does not require when a user needs a taxi.
"If we could use Cassandra for everything we would," Gardner adds. "We've kind of installed it and left it. It just works."
Starting on a larger scale, fast-growing music streaming service Spotify began as "pretty heavy PostgreSQL users", according to Nicholas Harteau, director of engineering at Spotify.
But then things got complicated; the company needed to replicate data and had high level problems that drove it to look at other storage solutions.
Driven by its high availability and replication capabilities, Spotify adopted Cassandra in 2010.
"It really is our go-to storage solution," Harteau says. "We still do a lot of PostgreSQL; but less and less as we need it for transactional and relational uses."
Spotify has about 35 clusters for different parts of the service, alongside 350 nodes and around 35TB of data.
Nowadays, the firm values NoSQL so much that it is looking at expanding its use of Cassandra. "In general we are looking at specific use cases," says Harteau. "We need to export large amounts of active data from Hadoop and current strategies don't work."
NoSQL is also a valuable tool for firms who need to process large amounts of analytic information. This is true of online video technology company Ooyala, which currently processes over two billion analytic events a day.
Ooyala's first analytics system was based on Oracle's MySQL, but problems started to appear when the firm needed to scale. "We started running into a lot of problems; having a global footprint became difficult," says Peter Bakas, the firm's director of platform engineering and operations.
And although Ooyala still uses Oracle's MySQL to store certain types of data, Cassandra's ability to scale out geographically was attractive. "Your availability is only as high as your lowest available component, so having a system that is available is key," says Bakas. "Since having Cassandra, if a node goes down, your whole system doesn't go down."
Meanwhile, for website and mobile social app SkillPages, the move to NoSQL and Cassandra was simple and fitted the business. The company is growing fast, with 2.7 million users at the end of 2011, 10.5 million in 2012, reaching around 18.5 million this year.
"Traditionally we started off as a Microsoft house," says CTO Mike McCarthy (pictured). "But as business grew, we used open source to help with scale; we look for tech that works."
As a growing business, scale is important to SkillPages. The firm, which syncs social media accounts, estimates it is processing three to four billion objects on a daily basis.
"Infrastructure out the box is essential to us," says McCarthy. "We could have built it ourselves but it would have been a huge overhead. It's scaling out the cluster now, which isn't a huge deal."