In general, these components are various types of metadata, providing information about data. Specific contents in a data dictionary can vary. Passive data dictionaries require an additional step to stay in sync with the databases they describe and must be handled with care to ensure there are no discrepancies. These are data dictionaries created as new databases - separate from the databases they describe - for the purpose of storing data dictionary information. This avoids any discrepancies between the data dictionaries and their database structures. These are data dictionaries created within the databases they describe automatically reflect any updates or changes in their host databases. Active and passive data dictionaries differ in level of automatic synchronization. There are two types of data dictionaries. The data dictionary would describe each of the data items in its data model for consumer banking, such as "Account holder" and "Available credit." Types of data dictionaries They could then provide a data dictionary for a bank's programmers. For example, a bank or group of banks could model the data objects involved in consumer banking. When developing programs that use the data model, a data dictionary can be consulted to understand where a data item fits in the structure, what values it may contain and what the data item means in real-world terms. This data collection can be organized for reference into a book called a data dictionary. The type of data, such as text or image or binary value, is described, possible predefined default values are listed and a brief textual description is provided. After each data object or item is given a descriptive name, its relationship is described, or it becomes part of some structure that implicitly describes relationship. This process is called data modeling and results in a picture of object relationships. Often a data dictionary is a centralized metadata repository.Ī first step in analyzing a system of interactive objects is to identify each one and its relationship to other objects. A data dictionary is a collection of descriptions of the data objects or items in a data model for the benefit of programmers and others who need to refer to them.
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