VECTOR_SUB
Returns a vector blob from two input vectors by subtracting the second vector from the first vector.
It is a scalar function.
Syntax
VECTOR_SUB(vector_expression, vector_expression)
Arguments
vector_expression: An expression that evaluates to a vector. The vector must be encoded as a blob containing packed single-precision or double-precision floating-point numbers in little-endian byte order.
Return Type
A blob containing packed single-precision floating-point numbers in little-endian byte order.
Remarks
To execute this function, the host processor must support AVX2 instruction set extensions. If AVX2 is not supported, an error will occur during execution.
Examples
Example: SELECT Using VECTOR_SUB() on Existing Rows
The following example executes VECTOR_SUB() on a row containing two vectors. The HEX() built-in function is also used to return a readable form of the binary output.
Create a table with two BLOB-typed columns:
CREATE TABLE vsub_t (a BLOB, b BLOB);
Using the JSON_ARRAY_PACK() built-in function to easily insert properly formatted vectors, insert a row with each vector in a different column:
INSERT INTO vsub_t VALUES(JSON_ARRAY_PACK('[0.7, 0.2, 1.7]'), JSON_ARRAY_PACK('[1.0, 0.5, 2.0]'));
To demonstrate the contents of the table, use the HEX() built-in function to return a readable form of the binary data:
SELECT HEX(a), HEX(b) FROM vsub_t; **** +--------------------------+--------------------------+ | HEX(a) | HEX(b) | +--------------------------+--------------------------+ | 3333333FCDCC4C3E9A99D93F | 0000803F0000003F00000040 | +--------------------------+--------------------------+
Query the table using the VECTOR_SUB() function in a SELECT statement:
SELECT HEX(VECTOR_SUB(a, b)) FROM vsub_t; **** +---------------------------+ | HEX(VECTOR_SUB(a, b)) | +---------------------------+ | 9A9999BE9A9999BE989999BE | +---------------------------+
Example: VECTOR_SUB() with JSON_ARRAY_PACK()
The following example uses JSON_ARRAY_PACK() as input parameters to the VECTOR_SUB() built-in function. The HEX() built-in function is also used to return a readable form of the binary output:
SELECT HEX(VECTOR_SUB(JSON_ARRAY_PACK('[1.0, 0.5, 2.0]'), JSON_ARRAY_PACK('[0.7, 0.2, 1.7]')));
+-----------------------------------------------------------------------------------------+
| HEX(VECTOR_SUB(JSON_ARRAY_PACK('[1.0, 0.5, 2.0]'), JSON_ARRAY_PACK('[0.7, 0.2, 1.7]'))) |
+-----------------------------------------------------------------------------------------+
| 9A99993E9A99993E9899993E |
+-----------------------------------------------------------------------------------------+
1 row in set (0.11 sec)