14.21 Vector Functions

MySQL 9.0 supports SQL functions to work with VECTOR values. These functions are described in this section.

Table 14.31 Vector Functions

Name	Description
STRING_TO_VECTOR()	Get the binary value of the VECTOR column represented by a conforming string
VECTOR_DIM()	Get the length of a vector (that is, the number of entries it contains)
VECTOR_TO_STRING()	Get the string representation of a VECTOR column, given its value as a binary string

• STRING_TO_VECTOR(string)

  Converts a string representation of a vector to a binary one. The expected format of the string consists of a list one or more comma-separated float values, encased in square brackets ([ ]). Values may be expressed using decimal or scientific notation. Since the argument is a string, it must be quoted.

  TO_VECTOR() is a synonym for this function.

  Examples:

  mysql> SELECT STRING_TO_VECTOR("[1.05, -17.8, 32]");
  +---------------------------------------+
  | STRING_TO_VECTOR("[1.05, -17.8, 32]") |
  +---------------------------------------+
  | 0x6666863F66668EC100000042            |
  +---------------------------------------+
  1 row in set (0.00 sec)
  
  mysql> SELECT TO_VECTOR("[1.05, -17.8, 32, 123.456]");
  +-----------------------------------------+
  | TO_VECTOR("[1.05, -17.8, 32, 123.456]") |
  +-----------------------------------------+
  | 0x6666863F66668EC10000004279E9F642      |
  +-----------------------------------------+
  1 row in set (0.00 sec)

  VECTOR_TO_STRING() is the inverse of this function:

  mysql> SELECT VECTOR_TO_STRING(STRING_TO_VECTOR("[1.05, -17.8, 32]"));
  +---------------------------------------------------------+
  | VECTOR_TO_STRING(STRING_TO_VECTOR("[1.05, -17.8, 32]")) |
  +---------------------------------------------------------+
  | [1.05000e+00,-1.78000e+01,3.20000e+01]                  |
  +---------------------------------------------------------+
  1 row in set (0.00 sec)

• VECTOR_DIM(vector)

  Given a VECTOR column value, this function returns the number of entries the vector contains.

  Example:

  mysql> SELECT VECTOR_DIM(0x0040004000800080);
  +--------------------------------+
  | VECTOR_DIM(0x0040004000800080) |
  +--------------------------------+
  |                              2 |
  +--------------------------------+
  1 row in set (0.00 sec)
  
  mysql> SELECT VECTOR_DIM(TO_VECTOR('[2, 3, 5]') );
  +-------------------------------------+
  | VECTOR_DIM(TO_VECTOR('[2, 3, 5]') ) |
  +-------------------------------------+
  |                                   3 |
  +-------------------------------------+
  1 row in set (0.00 sec)

  An argument to this function that cannot be parsed as a vector value raises an error.

• VECTOR_TO_STRING(vector)

  Given the binary representation of a VECTOR column value, this function returns its string representation, which is in the same format as described for the argument of the STRING_TO_VECTOR() function.

  FROM_VECTOR() is accepted as a synonym for this function.

  Examples:

  mysql> SELECT VECTOR_TO_STRING(0x00000040000040400000A0400000E040);
  +------------------------------------------------------+
  | VECTOR_TO_STRING(0x00000040000040400000A0400000E040) |
  +------------------------------------------------------+
  | [2.00000e+00,3.00000e+00,5.00000e+00,7.00000e+00]    |
  +------------------------------------------------------+
  1 row in set (0.00 sec)
  
  mysql> SELECT FROM_VECTOR(0x00000040000040400000A040);
  +-----------------------------------------+
  | FROM_VECTOR(0x00000040000040400000A040) |
  +-----------------------------------------+
  | [2.00000e+00,3.00000e+00,5.00000e+00]   |
  +-----------------------------------------+
  1 row in set (0.00 sec)

  An argument to this function that cannot be parsed as a vector value raises an error.

  The maximum size of the output of this function is 262128 (16 * 16383) bytes.