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Table 14.31 Vector Functions

• DISTANCE(vector,vector,string)

  Calculates the distance between two vectors per the specified calculation method. It accepts the following arguments:

  • A column ofVECTOR data type.

  • An input query ofVECTOR data type.

  • A string that specifies the distance metric. The supported values areCOSINE,DOT, andEUCLIDEAN. Since the argument is a string, it must be quoted.

  VECTOR_DISTANCE is a synonym for this function.

  Examples:

  mysql> SELECT DISTANCE(STRING_TO_VECTOR("[1.01231, 2.0123123, 3.0123123, 4.01231231]"), STRING_TO_VECTOR("[1, 2, 3, 4]"), "COSINE");+-----------------------------------------------------------------------------------------------------------------------+| DISTANCE(STRING_TO_VECTOR("[1.01231, 2.0123123, 3.0123123, 4.01231231]"), STRING_TO_VECTOR("[1, 2, 3, 4]"), "COSINE") |+-----------------------------------------------------------------------------------------------------------------------+|                                                                                              0.0000016689300537109375 |+-----------------------------------------------------------------------------------------------------------------------+

  Note

  DISTANCE() is available only for users of HeatWave MySQL on OCI; it is not included in MySQL Commercial or Community distributions.

• 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 aVECTOR 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 aVECTOR column value, this function returns its string representation, which is in the same format as described for the argument of theSTRING_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.