REFRESH VECTOR INDEX

Builds a Vector index for existing data that was inserted before the index was created.

Syntax

REFRESH VECTOR INDEX <index_name> ON [<database>.]<table_name>

When to Use REFRESH

REFRESH VECTOR INDEX is only needed in one specific scenario: when you create a Vector index on a table that already contains data.

The existing rows (written before the index was created) will not be automatically indexed. You must run REFRESH VECTOR INDEX to build the index for this pre-existing data. After the refresh completes, all subsequent data writes will automatically generate the index.

Examples

Example: Index Existing Data

-- Step 1: Create a table without an index
CREATE TABLE products (
    id INT,
    name VARCHAR,
    embedding VECTOR(4)
) ENGINE = FUSE;

-- Step 2: Insert data (without index)
INSERT INTO products VALUES
    (1, 'Product A', [0.1, 0.2, 0.3, 0.4]),
    (2, 'Product B', [0.5, 0.6, 0.7, 0.8]),
    (3, 'Product C', [0.9, 1.0, 1.1, 1.2]);

-- Step 3: Create vector index on existing data
CREATE VECTOR INDEX idx_embedding ON products(embedding) distance='cosine';

-- Step 4: Refresh to build index for the 3 existing rows
REFRESH VECTOR INDEX idx_embedding ON products;

-- Step 5: New insertions are automatically indexed (no refresh needed)
INSERT INTO products VALUES (4, 'Product D', [1.3, 1.4, 1.5, 1.6]);