July 2025, Release Update 23.9

Included are some notable Oracle AI Vector Search updates with Oracle Database 23ai, Release Update 23.9.

Feature	Description
IVF Index Reorganization	The quality of an IVF index may degrade over time if updates are made to the base table after the general vector distribution. IVF index reorganization permits the index to be reorganized while it remains available for DMLs and queries. Inverted File Flat Vector Indexes Online Rebuild
HNSW Index Snapshots	Incremental snapshots are introduced as an HNSW graph refresh mechanism optimized for minimal, frequent updates, balancing performance and memory use. HNSW Incremental Snapshots
Partition Maintenance Operation support for global IVF and HNSW Indexes	Partition Maintenance Operations can now be performed on partitioned tables that have global IVF and HNSW Indexes, including operations such as adding, dropping, merging, and splitting partitions. Partition Maintenance Operations and Vector indexes Partition Maintenance Operations with GLOBAL Vector Indexes
`SPARSE` HNSW Indexes	Hierarchical Navigable Small World (HNSW) vector indexes support `SPARSE` vectors. SPARSE Vectors
Creating Hybrid Vector Index using `DBMS_SEARCH` API	Hybrid Vector Indexes (HVI) can now be created using the `DBMS_SEARCH` PL/SQL package. Creating Hybrid Vector Indexes using DBMS_SEARCH API
Enhancements for altering Hybrid Vector Indexes	Existing Hybrid Vector Indexes can be altered using the `SQL ALTER INDEX` syntax to change settings such as replacing the vectorizer preference, the embedding model, or the type of vector index. ALTER INDEX
Enhancements for searching Hybrid Vector Indexes using the `DBMS_HYBRID_VECTOR.SEARCH` API	The `SEARCH` API for Hybrid Vector Indexes adds support for Weighted Reciprocal Rank Fusion (WRRF) as a method to search scores from keyword and semantic search results. It is also possible to define custom score calculations using a new parameter: `score_calc`. Additional enhancements include a new query parameter for keyword searches of Hybrid Vector Indexes as well as the ability to filter results using standard relational logic. SEARCH

Parent topic: Oracle Database 23ai Release Updates