Gary Mak

NoSQL and BigData

Most applications use a relational database like Oracle, MySQL, or Postgresql; however there is more too data storage then just SQL databases. There are:

Batch Processing and Native SQL

is the processing of groups of elements. From an application standpoint, batch processing means reading data from a persistent store, doing something with the data, and then possibly storing the processed data in the persistent store as a single conceptual operation. Batch processing, which allows for the automation and sharing of computer resources, is usually run when computer resources are less busy.

HQL and JPA Query Language

When you use JDBC to access databases, you write SQL statements for the query and update tasks. In such cases, you’re dealing with tables, columns, and joins. When you use Hibernate, most update tasks can be accomplished through the provided APIs. However, you still need to use a query language for the query tasks, and Hibernate provides a powerful query language called Hibernate Query Language (HQL).

Working with Objects

This chapter discusses the states an object goes through during its life cycle. The session is responsible for managing object state in Hibernate, and the EntityManager does the same in Java Persistence. Hibernate provides a persistence mechanism that is transparent to the entities and the application; the application has to know the state of an object.

Transactions and Concurrency

Let’s say that a buyer logs in to the bookshop application and purchases a book. The following actions should take place in the event of a purchase:

Querying with Criteria and Example

In the previous chapter, you saw how to use Hibernate Query Language (HQL) and Java Persistence Query Language (JPA QL). HQL forces you to interact with the database using SQL-like syntax. You must have some knowledge of SQL to create complex queries, which makes it difficult to develop applications that use multicriteria queries.

Many-to-One and One-to-One Mapping

In general, entities are related or associated to each other. For example, a Customer entity is associated with an Address entity. A Customer entity can have one or more than one Address entity (for example, Billing and Shipping). These relationships or associations are represented differently in a relational model and the domain/object model.

Caching in Hibernate

Caching is one of the important features implemented by an application for better performance. From an ORM perspective, data retrieved from a database is cached in memory or to disk, so there is no need to make a call to the database for every request. A cache is a local copy of the information from the database that can be used to avoid a database call whenever the following situations occur:

Starting with Hibernate

An object model uses the principles of abstraction, encapsulation, modularity, hierarchy, typing, concurrency, polymorphism, and persistence. The object model enables you to create well-structured and complex systems. In an object model system, objects are the components of the system. Objects are instances of classes, and classes are related to other classes via inheritance relationships. An object has an identity, a state, and a behavior. An object model helps you create reusable application frameworks and systems that can evolve over time. In addition, object-oriented systems are usually smaller than non-object-oriented implementations.

Many-Valued Associations

A many-valued association is by definition a collection of references to entities. The collection can be of type List, Set, Map, and so on in Java.