Data dictionaries are used to define different data structures. In a data dictionary, all important facts about the data flows and data stores are defined.
Data flow entries in a data dictionary:
- Data flow name - meaningful and complete name
- Data flow description - what is the data flow, what is its purpose etc.
- Aliases - other names the data flow is known by
- Origin or source
- Timing and volume - how often does the data flow happen, how many occurences of the data flow happen on average, on peaks and at low points
- Data structure - content of the data flow (elements that make up the data flow)
- Elements in the data structure - definition of each including name, type, source etc.
Data Store entries in a Data Dictionary:
- Data store name - meaningful and complete
- Data store description - what is the data store, what is its purpose etc.
- Source - data flows that bring the data to the store
- Output data flows - flows that take information from the store
- Data structure - view of the record and the elements - relationship to the overall file structure
- Identifier elements - any data element that can be used as key - determined by a data element whose values determine one and only one occurrence (record) in the data store
- Elements in the data structure - name, type, source etc.
- Volume and frequency - how many records will be stored (present, future, growth rate)
- Security - restrictions on seeing, changing and using the data
Data Elements Entries in a Data Dictionary:
- Data element name - meaningful and complete
- Data element description
- Aliases - list all names that the element can be called in any application, flow, or store in which it appears
- Files or systems element occurs in
- Values and defaults - what values or range of values can the element assume? Is there a default value? Values are indefinite values, value ranges or finite values
- Type and length of each element
- Output format
- Source - origination of element (entity, store, calculation etc.)
- Source responsibility contact
- Formula or calculation if applicable
Processes in a Data Dictionary:
- Process name - name as it appears in the data flow diagram and other types of documentation
- Aliases - all other names that the process can be none by
- Overview description
- Detailed processing description - step by step processing to accomplish the overview description
- Input data flows - flows that bring data to the process
- Output data flows - flows that take data from the process
External Entities in a Data Dictionary:
- Entity name
- Input data flows
- Output data flows