Inverted File Flat ALTER INDEX

Review the syntax and examples for altering and rebuilding Inverted File Flat vector indexes.

Syntax

Use the following syntax to rebuild the IVF vector index:

ALTER INDEX ivf_index_name REBUILD ONLINE 
[PARALLEL <degree of parallelism>];

Consider an IVF index created using syntax and parameters specified in this topic: Inverted File Flat CREATE INDEX.

CREATE VECTOR INDEX galaxies_ivf_idx ON galaxies (embedding) 
ORGANIZATION NEIGHBOR PARTITIONS
DISTANCE COSINE
WITH TARGET ACCURACY 95;

You can rebuild the IVF index galaxies_ivf_idx created above using the ALTER INDEX syntax:

ALTER INDEX galaxies_ivf_idx REBUILD ONLINE PARALLEL 4;

Note:

The ALTER INDEX considers all the parameters that were used to create the vector index, except the NEIGHBOR PARTITIONS parameter. This parameter is calculated internally based on the size and shape of the data that is introduced by the new DMLs.