What’s New in MongoDB 4.0? Transactions, Aggregation, and Platform Updates
MongoDB 4.0 has been officially released, bringing multi‑document ACID transactions, new aggregation operators, driver compatibility updates, enhanced security features, deprecation of the MMAPv1 storage engine, and broader platform support, while also offering free cloud monitoring for standalone and replica set deployments.
Release Overview
MongoDB 4.0, the latest version of the open‑source document database, is now generally available. It promises higher performance, greater availability, and automatic scaling, and can be downloaded from the official MongoDB Download Center.
Key New Features
▍Multi‑Document Transactions
MongoDB 4.0 introduces true ACID‑compliant multi‑document transactions for replica sets. All writes performed inside a transaction remain invisible outside the transaction until it is committed, guaranteeing atomicity.
▍Aggregation Enhancements
New aggregation operators support type conversion, and additional string manipulation operators have been added. (Images illustrating the operators are included in the original article.)
▍Driver Compatibility
The release adds compatibility with the latest MongoDB drivers; a visual matrix of supported drivers is provided in the source.
▍Security Improvements
MongoDB now supports SCRAM‑SHA‑256; to enable it, set featureCompatibilityVersion to 4.0 and configure the new scramSHA256IterationCount parameter. macOS binaries support TLS 1.2 only, and TLS 1.0 is disabled on systems that support newer versions. Windows Enterprise no longer supports AES256‑GCM.
▍MMAPv1 Deprecation
The MMAPv1 storage engine is deprecated starting with version 4.0 and will be removed in future releases.
▍Replica Set Changes
Protocol version 0 (pv0) for replica sets has been removed.
▍Change Streams
A new startAtOperationTime option allows change streams to specify a starting point.
▍Free Monitoring
Community Edition now offers free cloud‑based monitoring for both standalone and replica set deployments.
▍Sharded Cluster Enhancements
The mongos process now completes metadata‑affecting operations using the "majority" write concern.
▍Platform Support
Added support for Amazon Linux 2 and Debian 9 “Stretch” (Community & Enterprise).
Added support for s390x RHEL 6.x (Community only).
Dropped support for SLES 11, Ubuntu 12.04, and older Windows versions (7/2008 R2, 8/20012, 8.1/20012R2, Ubuntu 14.04).
▍General Improvements
Various updates to commands, geospatial queries, networking, and configuration options are included.
Further Information
Detailed release notes and driver documentation are available at the official MongoDB documentation site.
Source: Open Source China – https://www.oschina.net/news/97524/mongodb-4-0-released
Signed-in readers can open the original source through BestHub's protected redirect.
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