## Core Server Enhancements 

• concurrency (page 758) improvements 

• indexing memory improvements 

• background index creation (page 508) 

• better detection of regular expressions so the index can be used in more cases 

## Replication and Sharding 

• better handling for restarting slaves offline for a while 

• fast new slaves from snapshots ( --fastsync ) 

• configurable slave delay ( --slavedelay ) 

• replication handles clock skew on master 

• $inc replication fixes 

• sharding alpha 3 - notably 2-phase commit on config servers 

## Deployment and Production 

• configure “slow threshold” for profiling (page 228) 

• ability to do fsync + lock for backing up raw files 

• option for separate directory per db ( --directoryperdb ) 

• http://localhost:28017/_status to get serverStatus via http 

• REST interface is off by default for security ( --rest to enable) 

• can rotate logs with a db command, logRotate 

• enhancements to serverStatus command (db.serverStatus()) - counters and replication lag (page 647) stats 

• new mongostat tool 

## Query Language Improvements 

• $all with regex 

• $not 

• partial matching of array elements $elemMatch 

• $ operator for updating arrays 

• $addToSet 

• $unset 

• $pull supports object matching 

• $set with array indexes 

