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0580 Data Dictionaries

At the start of a data project, it is often necessary to describe the types of data that is needed. This is called a data specification.
DataField entities are used to model specific data fields required by the data project. As the project progresses, data schemas are defined to describe how data is organized in the different data assets used by the project.

The data dictionary maintains lists of pre-defined, reusable data fields.

UML

DataField entity

An AuthoredReferenceable that describes a data field.

  • namespacePath - Optional namespace to help build a qualified name for the data field.
  • aliases - Alternative name to use for the data field - useful when matching against a schema.
  • namePatterns - List of patterns to use to match a name against a schema attribute - useful when matching against a schema.
  • defaultValue - Default value to use if the actual data value is null.
  • isNullable - Can the data field store null?
  • dataType - What is the data type of this field
  • units - What are the units used in the data values stored under this data field
  • minimumLength - What is the minimum length of this field - typically used with string fields.
  • length - What is the length (in bytes) taken up by this field.
  • precision - How many digits after the decimal point.
  • orderedValues - Are the values sorted
  • sortOrder - DataItemSortOrder value identifying the sort direction used on the data field values.

ObjectIdentifier classification

The ObjectIdentifier classification indicates that a data item is typically used as a unique identifier. It is typically attached to a data field.

DataDictionary Entity

Identifies that a collection is a data dictionary. This is an organized collection of defined data fields that can be used as a knowledge base of preferred data definitions for data professionals.

DataSpec Entity

Identifies that this is a collection is a data specification that describes the data requirements for a project or initiative. Its members are typically data structures.

ReportType entity

The ReportType entity describes a report design. It specifies the schema (structure) of the data that will be assembled in a populated report. It has the following attributes:

  • creationTime - the time the report type was created.
  • lastModificationTime - the time the report type content was last modified.

  • lastModifier - the userId of the last person to modify the report type.

  • createdTime - Report create time.

  • lastModifiedTime - Report last modified time.
  • lastModifier - UserId of the report last modifier.

DataStructure entity

An AuthoredReferenceable that provides list of data fields that describe the structure of a data source within a data specification.

  • namespacePath - Optional namespace to help build a qualified name for the data structure.
  • namePatterns - List of patterns to use to match a name against a schema attribute - useful when matching against a schema.

It is used to specify/validate the values in an asset's schema, which in turn describes the structure of data in the digital resource.

MemberDataField relationship

Represents an association between a data structure and one of its data fields.

  • coverageCategory - Used to describe how a collection of data values for an attribute covers the domain of the possible values to the linked attribute.
  • position - Position of the element in a collection of relationships. Zero means no position set. A positive value identified the position starting from 1 for the first position.
  • minCardinality - Minimum number of allowed instances.
  • maxCardinality - Maximum number of allowed instances.

DataDescription relationship

Represents an association between a referenceable, such as a digital product, and a collection of data fields that describes some data.

DataStructureDefinition relationship

Represents an association between a data structure that describes a data source and a certification type that indicates that certified elements conform to the data structure and associated definitions (such as glossary term and data class).

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