inner_product()

The INNER PRODUCT function returns the negated dot product (-dot product) as a vector distance; smaller values indicate more similar vectors.

Function Description

The INNER PRODUCT function returns the negated dot product (-dot product) as a vector distance; smaller values indicate more similar vectors. To obtain the mathematical dot product, use -inner_product(vector1, vector2).

Function syntax

> SELECT inner_product(vector1, vector2) AS result FROM table_name;

Examples

drop table if exists vec_table;
create table vec_table(a int, b vecf32(3), c vecf64(3));
insert into vec_table values(1, "[1,2,3]", "[4,5,6]");
mysql> select * from vec_table;
+------+-----------+-----------+
| a    | b         | c         |
+------+-----------+-----------+
|    1 | [1, 2, 3] | [4, 5, 6] |
+------+-----------+-----------+
1 row in set (0.00 sec)

mysql> select inner_product(b,"[1,2,3]") from vec_table;
+---------------------------+
| inner_product(b, [1,2,3]) |
+---------------------------+
|                       -14 |
+---------------------------+
1 row in set (0.00 sec)

Distance semantics

INNER_PRODUCT returns -dot product to use the same distance-ordering convention as vector indexes. With ORDER BY inner_product(...) ASC, smaller values indicate more similar vectors; using DESC reverses the similarity ordering. To obtain the mathematical dot product, use -inner_product(vector1, vector2).

Restrictions

Two parameter vectors must have the same dimension.