8-Bit Integer Vector: `veci8`

Int8 is a data type used to represent signed integers. It stands for “integer 8-bit” and typically uses 8 bits of memory to store a value. This allows it to represent integer values ranging from -128 to 127.

Since each element in the vector only requires 8 bits (1 byte) of memory, veci8 can help reduce the overall memory footprint of your program.

Here’s an example of creating a table with a veci8 column and inserting values:

CREATE TABLE items (
  id bigserial PRIMARY KEY,
  embedding veci8(3) NOT NULL
);

INSERT INTO items (embedding) VALUES ('[1, 2, 0]'), ('[-1, 15, -2]');

Index can be created on veci8 type as well.

CREATE INDEX your_index_name ON items USING vectors (embedding veci8_l2_ops);

SELECT * FROM items ORDER BY embedding <-> '[0.3,0.2,0.1]' LIMIT 1;

We support three operators to calculate the distance between two veci8 values.

• <-> (veci8_l2_ops): squared Euclidean distance, defined as $\Sigma (x_i - y_i) ^ 2$.
• <#> (veci8_dot_ops): negative dot product, defined as $- \Sigma x_iy_i$.
• <=> (veci8_cos_ops): cosine distance, defined as $1 - \frac{\Sigma x_iy_i}{\sqrt{\Sigma x_i^2 \Sigma y_i^2}}$.