Inverted File Flat CREATE INDEX

Syntax and examples for creating Inverted File Flat vector indexes.

Syntax

CREATE VECTOR INDEX <vector index name>
ON <table name> ( <vector column> )
[GLOBAL] ORGANIZATION [NEIGHBOR] PARTITIONS
[WITH] [DISTANCE <metric name>]
[WITH TARGET ACCURACY <percentage value>]
[QUANTIZATION SCALAR COMPRESSION RATIO {2 | 4 | 8}]
[PARAMETERS ( TYPE IVF,
              { NEIGHBOR PARTITIONS <number of partitions> |
                SAMPLES_PER_PARTITION <number of samples> |
                MIN_VECTORS_PER_PARTITION <minimum number of vectors per partition> |
                NEIGHBOR PARTITION GROUPING <ON | OFF> },
              RESCORE FACTOR rescore_factor
            )]
[PARALLEL <degree of parallelism>]
[LOCAL];

The GLOBAL clause specifies a global IVF index. By default, IVF vector indexes are globally partitioned by centroid.

Specify the LOCAL clause to create a local IVF index.

IVF Parameters

Parameter	Purpose
`NEIGHBOR PARTITIONS`	Determines the target number of centroid partitions that are created by the index.
`SAMPLES_PER_PARTITION`	Decides the total number of vectors that are passed to the clustering algorithm (`samples_per_partition * neighbor_partitions`). Passing all the vectors could significantly increase the total index creation time. The goal is to pass in a subset of vectors that can capture the data distribution.
`MIN_VECTORS_PER_PARTITION`	Represents the target minimum number of vectors per partition. The goal is to trim out any partition that can end up with few vectors (<= 100).
`NEIGHBOR PARTITION GROUPING`	Enables, in addition to partitioning, further data grouping in the storage layer for centroids in the IVF index. This can result in query performance benefits in serial, parallel, and multi-user (concurrent) queries due to additional pruning during the scan. When this storage optimization is enabled, the default number of centroids may increase, which can lead to a longer IVF index creation time. To disable this feature, you must drop the index and recreate it. Neighbor partition grouping will continue to be enabled on an index that is rebuilt. Online index rebuild is supported on IVF indexes that have this storage option enabled. Neighbor partition grouping can only be specified upon index creation and cannot be enabled or disabled using `ALTER INDEX` or `REBUILD`. This parameter is only applicable to global IVF indexes. It is not supported with HNSW indexes or local IVF indexes.
`RESCORE FACTOR`	An optional integer parameter that defines the rescoring multiplier for semantic search queries. It has a default value of 1 and is applied only when the index is quantized (when `QUANTIZATION` is specified).

The valid range for IVF vector index parameters are:

Parameter	Valid Values
`ACCURACY`	> 0 and <= 100
`DISTANCE`	`COSINE` (default) `EUCLIDEAN` `L2_SQUARED` (as in `EUCLIDEAN_SQUARED`) `DOT` `MANHATTAN` `HAMMING`
`QUANTIZATION`	`SCALAR`
`TYPE`	`IVF`
`NEIGHBOR PARTITIONS`	>0 and <= 10000000
`SAMPLES_PER_PARTITION`	From 1 to (`num_vectors`/`neighbor_partitions`)
`MIN_VECTORS_PER_PARTITION`	From 0 (no trimming of centroid partitions) to total number of vectors (which would result in 1 centroid partition)
`NEIGHBOR PARTITION GROUPING`	`ON` \| `OFF`. The default value is `OFF`.
`RESCORE FACTOR`	>= 1 and <= 100 (default 1)

Usage Notes

You can optionally use the QUANTIZATION keyword together with the COMPRESSION RATIO parameter in order to apply scalar quantization to a new vector index.

The COMPRESSION RATIO specifies the level of compression for a vector column when creating a scalar-quantized index. Higher compression ratios yield smaller storage requirements but increased quantization. The possible values for COMPRESSION RATIO are 2, 4, and 8.

The following table shows the resulting data type stored in the index for each compression ratio, depending on the original vector column format.

Compression Ratio	FLOAT64 Input	FLOAT32 Input
2	FLOAT32	Not Supported
4	Not Supported	INT 8
8	INT8	Not Supported

Note that “not supported” means that scalar quantization is not available for the given combination of compression ratio and vector column format.

If the original vector column has a flex format, quantization is only supported when the dimension and type can be resolved to a valid input type from the table data.

Note: Float16 is not currently a valid input format for scalar quantization with IVF indexes.

Examples

To create a global IVF index:

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

CREATE VECTOR INDEX galaxies_ivf_idx ON galaxies (embedding)
ORGANIZATION NEIGHBOR PARTITIONS
DISTANCE COSINE
WITH TARGET ACCURACY 90
PARAMETERS (
    TYPE IVF,
    NEIGHBOR PARTITIONS 10
);

CREATE VECTOR INDEX galaxies_ivf_idx ON galaxies (embedding)
ORGANIZATION NEIGHBOR PARTITIONS
DISTANCE EUCLIDEAN
WITH TARGET ACCURACY 95
PARAMETERS (
    TYPE IVF,
    NEIGHBOR PARTITIONS 100,
    NEIGHBOR PARTITION GROUPING ON
) TABLESPACE my_tablespace;

CREATE VECTOR INDEX quantized_ivf_idx ON galaxies (embedding)
ORGANIZATION NEIGHBOR PARTITIONS
DISTANCE EUCLIDEAN
WITH TARGET ACCURACY 95
QUANTIZATION SCALAR
COMPRESSION RATIO 4
PARAMETERS (
  TYPE IVF,
  NEIGHBOR PARTITIONS 2,
  RESCORE FACTOR 2
);

To create a local IVF index:

CREATE VECTOR INDEX galaxies_ivf_idx ON galaxies (embedding)
ORGANIZATION NEIGHBOR PARTITIONS
DISTANCE COSINE
WITH TARGET ACCURACY 90
PARAMETERS (
    TYPE IVF,
    NEIGHBOR PARTITIONS 10
) LOCAL;

For detailed information on the syntax, see CREATE VECTOR INDEX in Oracle AI Database SQL Language Reference.

Create IVF Index Online

When the base table must remain available for ongoing updates and cannot be locked during index creation, use the ONLINE clause with CREATE VECTOR INDEX to build the IVF index online. This allows applications with heavy DML to continue updating the table while the index is being created.

See Also:

Partition Maintenance Operations with GLOBAL Vector Indexes