Microsoft recently open-sourced the Extensible Storage Engine (ESE, once known as JET Blue). ESE is a non-SQL database engine with more than 25 years of serviceable lifetime. It was started with Windows NT 3.51 and it still remains a core Microsoft asset to this day. Even today, Office 365 Mailbox Storage Backend servers, large SMP systems, and every single Windows client have ESE code.
- It’s running on 100s of thousands of machines and millions of disks for the Office 365 Mailbox Storage Backend servers
- It’s also running on large SMP systems with TB of memory for large Active Directory deployments
- Every single Windows Client computer has several database instances running in low memory modes. In over 1 billion Windows 10 devices today, ESE has been in use in Windows client SKUs since Windows XP
Here’s what ESE does:
ESE enables applications to store and retrieve data from tables using indexed or sequential cursor navigation. It supports denormalized schemas including wide tables with numerous sparse columns, multi-valued columns, and sparse and rich indexes. ESE enables applications to enjoy a consistent data state using transacted data update and retrieval. A crash recovery mechanism is provided so that data consistency is maintained even in the event of a system crash. ESE provides ACID (Atomic Consistent Isolated Durable) transactions over data and schema by way of a write-ahead log and a snapshot isolation model.
You can check out the GitHub repository of ESE from the source link below.