Chapter 2 Data Models Flashcards by Ross Honeyman

The graph data model is a more modern offshoot of network and hierarchical models. Typically paired with graph databases, it’s often used to describe data sets that contain complex relationships. For example, graph data modeling is a popular approach in social networks, recommendation engines pichon claude-michel 2019 val de loire sauvignon blanc privilege and fraud detection applications. The physical database model describes the specifics of how the logical model will be realized. It must contain enough detail to enable technologists to create the actual database structure in hardware and software to support the applications that will use it.

Both data and their relationships are contained in an object. A condition in which a model does not depend on the hardware used in the model’s implementation. Therefore, changes in the hardware will have no effect on the database design at the conceptual level.

These relationships are usually documented via unified modeling language . Identify the entities.The process of data modeling begins with the identification of the things, events or concepts that are represented in the data set that is to be modeled. Each entity should be cohesive and logically discrete from all others. The hierarchical model organizes data into a tree-like structure, where each record has a single parent or root. That order is used as the physical order for storing the database. This model is good for describing many real-world relationships.

Firstly we will assume we are engineering a new relational database schema from a class model we have created. This is obviously the easiest direction as the models remain under our control and we can optimise the relational data model to the class model. In the real world it may be that you need to layer a class model on top of a legacy data model – a more difficult situation and one that presents its own challenges. For the current discussion will focus on the first situation.

The data node stores fixed-size data blocks, that could be replicated to other data nodes. Representation of the conceptual model, usually expressed graphically. 3) A data manipulation methodology to support the real-world data transformations.

Visually, it’s like a collection of cubes, rather than two-dimensional tables. Relational databases are typically written in Structured Query Language . Within the database, tables can be normalized, or brought to comply with normalization rules that make the database flexible, adaptable, and scalable. When normalized, each piece of data is atomic, or broken into the smallest useful pieces.

A model for database consistency in which updates to the database will propagate through the system so that all data copies will be consistent eventually. Client node acts as the interface between the user application and the HDFS. The organization of classes in a hierarchical tree in which each parent class is a Superclass and each child class is a Subclass. Based on mathematical set theory and represents data as independent relations.

Because data modeling requires business input, it encourages collaboration between data management teams and business stakeholders, which ideally results in better systems. A weak entity is a type of entity which doesn’t have its key attribute. It can be identified uniquely by considering the primary key of another entity. The basic structure of data in the relational model is tables. All the information related to a particular type is stored in rows of that table. In this database model, relationships are created by dividing object of interest into entity and its characteristics into attributes.

Each file contains an index that references one or more key fields of each data record to its storage location address. Direct access- on-line processing requires direct access, whereby a record can be accessed without accessing the records between it and the beginning of the file. – A key a single attribute or a combination of two or more attributes of an entity set that is used to identify one or more instances of the set . Data Manipulation Language – A data manipulation language is a language that enables users to access or manipulate data as organized by the appropriate data model. Relational Model – The relational model was first introduced by E.F. The model uses the concept of a mathematical relation as its basic building block, and has its theoretical basis in set theory and first-order predicate logic.

It enabled organizations to bring consistency, repeatability and disciplined development to data processing and management. That’s still the case, but the techniques used to create data models have evolved along with the development of new types of databases and computer systems. Data modeling is the process of creating a simplified diagram of a software system and the data elements it contains, using text and symbols to represent the data and how it flows. Data models provide a blueprint for designing a new database or reengineering a legacy application.

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