VECTOR_SUBVECTOR
Derives a vector expression from another vector expression.
It is a scalar function.
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.
Suffix | Datatype |
|---|---|
| 8-bit signed integer |
| 16-bit signed integer |
| 32-bit signed integer |
| 64-bit signed integer |
| 32-bit floating-point number (IEEE standard format) |
| 64-bit floating-point number (IEEE standard format) |
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] | +-------+