13.3.5 The VECTOR Type

A VECTOR is a structure that can hold up to a specified number of entries N, defined as shown here:

VECTOR(N)

Each entry is a 4-byte (single-precision) floating-point value.

The default length is 2048; the maximum is 16383 entries. To declare a VECTOR column of the default length, define it as VECTOR with no parentheses following; trying to define a column as VECTOR() (with empty parentheses) raises a syntax error.

A VECTOR cannot be compared to any other type. It can be compared to another VECTOR for equality, but no other comparison is possible.

A VECTOR column cannot be used as any type of key. This includes all of the following types:

• Primary key

• Foreign key

• Unique key

• Partitioning key

A VECTOR column also cannot be used as a histogram source.

VECTOR Supported and Unsupported Functions

VECTOR values can be used with the MySQL string functions BIT_LENGTH(), CHAR_LENGTH(), HEX(), LENGTH(), and TO_BASE64(). Other string functions do not accept the VECTOR type as an argument.

VECTOR can be used as an argument to any of the encryption functions AES_ENCRYPT(), COMPRESS(), MD5(), SHA1(), and SHA2(). VECTOR is not supported as an argument type by any other encryption functions.

VECTOR can be used as an argument to the CASE operator and related flow-control functions, including COALESCE(), IFNULL(), NULLIF(), and IF().

VECTOR can be used as the argument to CAST(expression AS BINARY); the result is a binary string with the same contents as the VECTOR argument. Casting to VECTOR with CAST is not supported; you can convert a suitable string to VECTOR using VECTOR_TO_STRING().

VECTOR data types cannot be used as arguments to aggregate functions or window functions other than COUNT [DISTINCT].

VECTOR cannot be used as an argument to any of the following types of functions and operators:

• Numeric functions and operators

• Temporal functions

• Fulltext search functions

• XML functions

• Bit functions such as bitwise AND and OR

• JSON functions