Apple has open-sourced the technology from a NoSQL database start-up it bought back in 2015.

FoundationDB was originally available in both commercial and community flavours before it was bought out by Apple.
The product had caught the attention of database engineers well before Apple made its move.
At the time of the acquisition, it was rumoured that Apple would use the technology to replace a Cassandra NoSQL deployment underpinning several iMessage and iTunes functions.
In a statement, FoundationDB said it wanted to “become the foundation of the next generation of distributed databases.”
“Since its beginnings in 2010 as a startup, the world of databases has increasingly aligned with FoundationDB to favour data consistency,” it said.
“The vision of FoundationDB is to start with a simple, powerful core and extend it through the addition of ‘layers’.
“The key-value store, which is open sourced today, is the core, focused on incorporating only features that aren’t possible to write in layers.
“Layers extend that core by adding features to model specific types of data and handle their access patterns.”
FoundationDB said it expected “the quantity and variety of layers” available “to develop rapidly” now that the core was in open source.