From the post:
Neo4j 2.1.6 is a maintenance release, with critical improvements.
Notably, this release:
- Resolves a critical shutdown issue, whereby IO errors were not always handled correctly and could result in inconsistencies in the database due to failure to flush outstanding changes.
- Significantly reduce the file handle requirements for the lucene based indexes.
- Resolves an issue in consistency checking, which could falsely report store inconsistencies.
- Extends the Java API to allow the degree of a node to be easily obtained (the count of relationships, by type and direction).
- Resolves a significant performance degradation that affected the loading of relationships for a node during traversals.
- Resolves a backup issue, which could result in a backup store that would not load correctly into a clustered environment (Neo4j Enterprise).
- Corrects a clustering issue that could result in the master failing to resume its role after an outage of a majority of slaves (Neo4j Enterprise).
All Neo4j 2.x users are recommended to upgrade to this release. Upgrading to Neo4j 2.1, from Neo4j 1.9.x or Neo4j 2.0.x, requires a migration to the on-disk store and can not be reversed. Please ensure you have a valid backup before proceeding, then use on a test or staging server to understand any changed behaviors before going into production.
Neo4j 1.9 users may upgrade directly to this release, and are recommended to do so carefully. We strongly encourage verifying the syntax and validating all responses from your Cypher scripts, REST calls, and Java code before upgrading any production system. For information about upgrading from Neo4j 1.9, please see our Upgrading to Neo4j 2 FAQ.
For a full summary of changes in this release, please review the CHANGES.TXT file contained within the distribution.
As with all software upgrades, do not delay until the day before you are leaving on holiday!