VECTOR_KTH_ELEMENT
Returns the k-th element in a vector expression where k is 0-indexed.
It is a scalar function.
Syntax
VECTOR_KTH_ELEMENT(vector_expression, k)
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.k: An 0-indexed number to determine which element in the vector to be returned. A positive index counts from the beginning of the vector. A negative index counts from the end of the vector.
Return Type
An element at the K-th position of the given vector. An error that might be returned for out-of-bounds access: "ERROR 2609 (HY000): Index ... is out of range for an array/subarray of size ..."
Remarks
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.
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 vke_t (x BLOB);
INSERT INTO vke_t VALUES (JSON_ARRAY_PACK('[4,3,1,5,2]'));SELECT (VECTOR_KTH_ELEMENT(x,2)) AS x from vke_t; **** +---+ | x | +---+ | 1 | +---+
SELECT (VECTOR_KTH_ELEMENT(x,-3)) AS x from vke_t; **** +---+ | x | +---+ | 3 | +---+