VECTOR_SUBVECTOR

Syntax

VECTOR_SUBVECTOR(vector_expression, start_position, length)

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.

• start_position: A 0-indexed number to determine where to start count. A positive index counts from the beginning of the vector. A negative index counts from the end of the vector.

• length: Length of required subvector

Return Type

A blob containing packed single-precision floating-point numbers in little-endian byte order.

Remarks

A vector can be of any length, but the input blob length must be divisible by the packed vector element size (1, 2, 4 or 8 bytes, depending on the vector element).

You can specify the datatype of the vector elements in which this operation is performed on the vector by adding a suffix to the function. Omitting the suffix from the function is equivalent to suffixing it with _F32. All operations are done using the specified datatype. The following table lists the suffixes and their datatype.

Examples

CREATE TABLE vsv_t (x BLOB);
INSERT INTO vsv_t VALUES (JSON_ARRAY_PACK('[1,2,3,4,5]'));

SELECT JSON_ARRAY_UNPACK (VECTOR_SUBVECTOR(x,2,2)) AS x from vsv_t;

+-------+
| x     |
+-------+
| [3,4] |
+-------+

SELECT JSON_ARRAY_UNPACK (VECTOR_SUBVECTOR(x,-2,2)) AS x from vsv_t;

+-------+
| x     |
+-------+
| [4,5] |
+-------+