• Aggregation framework (since v.2.2) and enhancements (since v.2.6)
• TTL collections (since v.2.2)
• Concurrency improvements among which DB level locking (since v.2.2)
• Text search (since v.2.4) and integration (since v.2.6)
• Hashed index (since v.2.4)
• Security enhancements, role based access (since v.2.4)
• V8 JavaScript engine instead of SpiderMonkey (since v.2.4)
• Query engine improvements (since v.2.6)
• Pluggable storage engine API
• WiredTiger storage engine introduced, with document level locking while previous storage engine (now called MMAPv1) supports collection level locking