Develop
Calculate Distance
This section provides examples of how to calculate the distance between vectors and rows in a table. The examples use the books
table with the book_embedding
column, which contains the embeddings of books.
Overview
Currently we support the following distance functions and distance operators for calculating the distance between vectors.
Distance metric  Distance function  Distance operator  Supported data types 

Euclidean 



Cosine 



Hamming 



Distance functions
You can use the provided distance functions to calculate the distance between vectors
sql
SELECT l2sq_dist(ARRAY[0,0.1,0], ARRAY[0.5,0.0,0.2]);  Euclidean
SELECT cos_dist(ARRAY[0,1,0], ARRAY[1,1,1]);  Cosine
SELECT hamming_dist(ARRAY[0,1,0], ARRAY[1,1,1]);  Hamming
You can also use the provided distance functions to fetch records based on embedding distance without an index. This will run an exact search over all rows.
sql
SELECT title FROM books ORDER BY l2sq_dist(book_embedding, '{0,0,0}') LIMIT 2;
Distance operators
You can use the provided distance operators to calculate the distance between vectors
sql
SELECT ARRAY[0,0.1,0] <> ARRAY[0.5,0.0,0.2];  Euclidean
SELECT ARRAY[0,1,0] <=> ARRAY[1,1,1];  Cosine
SELECT ARRAY[0,1,0] <+> ARRAY[1,1,1];  Hamming
You can also use the provided distance operators to fetch records based on embedding distance. If there is an index created for the embedding column, this query will use the index. Otherwise, it will run an exact search over all rows.
sql
SELECT title FROM books ORDER BY book_embedding <> '{0,0,0}' LIMIT 2;