Create indexes and query vectors

This document shows you how to use stored embeddings to generate indexes and query embeddings. For more information about storing embedding, see Store vector embeddings.

You can create ScaNN, IVF, IVFFlat, and HNSW indexes with AlloyDB.

Caution: The postgres_ann extension is renamed to alloydb_scann. Before you upgrade to AlloyDB Omni, you must drop any indexes created using the older postgres_ann version. Next, upgrade AlloyDB Omni, and then create the indexes again using the alloydb_scann extension. This applies only to AlloyDB Omni.

Before you begin

Before you can start creating indexes, you must complete the following prerequisites.

• Embedding vectors are added to a table in your AlloyDB database.

• The vector extension version 0.5.0 or later that is based on pgvector, extended by Google for AlloyDB is installed.

  CREATE EXTENSION IF NOT EXISTS vector;
  

• To generate ScaNN indexes, install the alloydb_scann extension in addition to the vector extension.

  CREATE EXTENSION IF NOT EXISTS alloydb_scann;
  

Note: The alloydb_scann extension can be used with PostgreSQL 14 and 15 compatible databases.

Create an index

You can create one of the following index types for tables in your database.

Note: As the index names are shared across the database, create an index name unique to each table in your database.

ScaNN IVF IVFFlat HNSW

What's next

• An example embedding workflow
• Tune vector query performance
• Vector index metrics