Amazon Neptune adds online index rebuild to reclaim storage

AWS announced online index rebuild for Amazon Neptune Database on October 27, 2026. The company says the feature defragments indexes and reclaims unused storage without taking the database offline. Query processing continues on the writer instance and read replicas throughout the rebuild. AWS announcement

Why deleting data may not release storage

According to AWS, insert, update and delete operations can leave unused gaps inside data pages, keeping the VolumeBytesUsed metric elevated even after data is deleted. The company says this fragmentation increases I/O costs and degrades query performance for Gremlin, openCypher and SPARQL workloads at scale.

Online index rebuild addresses those gaps. Teams can rebuild all indexes, only quad indexes or only dictionary indexes. AWS lists post-deletion cleanup, periodic maintenance, storage-limit management and performance tuning on heavily fragmented databases as use cases. Feature details

Balance reclamation against workload demand

AWS says concurrency and write-buffer size are tunable to balance rebuild speed against workload impact. It also describes built-in storage safety mechanisms intended to protect against storage exhaustion during the operation. AWS feature announcement

For engineers, the important distinction is availability versus performance: keeping queries running is not a promise of unchanged latency. The tuning controls make rebuilding a resource-management decision, not simply a cleanup switch.

A cautious rollout would record storage consumption and application query latency before rebuilding, then compare them during and after the operation. Choose the index scope deliberately rather than defaulting to a full rebuild, and evaluate the workload impact before making rebuilding routine maintenance.

Availability and requirements

AWS lists support starting with Neptune engine 1.5.0.0, on provisioned writer instances, in all Regions where Amazon Neptune Database is supported. Verify the engine version and writer configuration before planning a rebuild. AWS availability statement