JSON Function Descriptor - Teradata Vantage

A JSON (JavaScript Object Notation) function descriptor is a JSON file that Teradata ML Engine uses for function metadata processing.

Major Sections of JSON Descriptor

Section	Description
Header	Specifies function name, version, and type information.
Input_tables	Specifies function ON clauses.
Argument_clauses	Specifies function arguments.

Header Section Fields

Field	Type	Description
json_schema_major_version	string	Major version of JSON schema. Set to "1".
json_schema_minor_version	string	Minor version of JSON schema. Set to "2".
json_content_version	string	JSON content version. Set to "1".
function_name	string	Name of function class file.
function_version	string	Version of function.
function_type	string	Specifies function type ("driver" or "non-driver").
short_description	string	Short description of function.
long_description	string	Long description of function.

Input_tables Section Fields

Field	Type	Description
name	string	Specifies ON clause alias.
datatype	string	Set to "TABLE_ALIAS" for each ON clause.
requiredInputKind	list of string	Specifies partition information of ON clause. Can be a combination of PartitionByKey, PartitionByAny, or Dimension.
partitionByOne	boolean	Specifies whether ON clause accepts PartitionByOne. For this to be true, requiredInputKind must be PartitionByKey.
isOrdered	boolean	Specifies whether ON clause accepts ORDER BY clause.
isRequired	boolean	Specifies whether ON clause is required.
description	string	Description of ON clause.

Argument_clauses Section Fields

Field	Type	Description
name	string	Specifies argument name.
datatype	string	Specifies data type of argument value; one of these: "BOOLEAN" "INTEGER" "DOUBLE" "LONG" "STRING" "TABLE_NAME" "COLUMN_NAMES" "COLUMNS"
isRequired	boolean	Specifies whether argument clause is required or optional.
defaultValue	Boolean, numeric, or string depending on the value of the data type.	Specifies default value of argument (value for function to use if the user omits argument). Specify only if isRequired is set to false.
permittedValues	list of string	Specifies permitted values of argument clause.
description	string	Description of argument clause.
isOutputTable	boolean	Specifies whether argument clause accepts database table as output. For this value to be true, data type must be set to "TABLE_NAME".

JSON Descriptor Example: GMMFit Function

{
 "json_schema_major_version": "1",
 "json_schema_minor_version": "2",
 "json_content_version": "1",
 "function_name": "GMMFit",
 "function_version": "1.2",
 "function_type": "driver",
 "short_description"; "Fits a Gaussian Mixture Model to data.",
 "long_description": "Clusters data using a Gaussian Mixture Model or a Dirichlet Process Gaussian Mixture Model.",
 "input_tables";[
  {
   "requiredInputKind":[
    "PartitionByKey"
   ],
   "isOrdered": false,
   "partitionByOne": true,
   "name": "init_params",
   "isRequired": true,
   "description": "Contains initial values for the cluster weights, means, and covariances.",
   "datatype": "TABLE_ALIAS"
  }
 ],
 "argument_clauses":[
  {
   "isOutputTable": false,
   "name":"InputTable",
   "isRequired": true,
   "description": "Specifies the name of the table that contains the input data to be clustered.",
   "datatype": "TABLE_NAME"
  },
  {
   "isOutputTable": true,
   "name":"OutputTable",
   "isRequired": true,
   "description": "Specifies the name of the output table to which the function outputs cluster information.",
   "datatype": "TABLE_NAME"
  },
  {
   "defaultValue": 20,
   "name": "MaxClusternum",
   "isRequired": false,
   "description": "Specifies the maximum number of clusters in a Dirichlet process model.",
   "datatype": "INTEGER"
  },
  {
   "permittedValues": [
    "SPHERICAL",
    "DIAGNONAL",
    "FULL",
    "TIED"
   ],
   "defaultValue": "DIAGONAL",
   "name": "CovarianceType",
   "isRequired": false,
   "description": "Specifies the type of the covariance matrices.",
   "datatype": "STRING"
  },
  {
   "defaultValue": 0.001,
   "name": "Tolerance",
   "isRequired": false,
   "description": "Specifies the minimum change in log-likelihood between iterations that causes the function to terminate.",
   "datatype": "DOUBLE"
  },
  {
   "defaultValue": false,
   "name": "PackOutput",
   "isRequired": false,
   "description": "Specifies whether the function packs the output. The default value is 'false'.",
   "datatype": "BOOLEAN"
  }
 ]
}