Lesson 1

Welcome to Database Creation and Architecture.

The full capabilities of the Oracle XQuery Virtual Machine can be accessed using a standalone application. This allows XQuery expressions to be performed directly from the command line without interacting with Oracle Database. It also enhances the Oracle XQuery Virtual Machine to add support for the XQuery Update standard as well as the emerging XQuery scripting language. The Oracle XQuery Virtual Machine and database can also share the same native XML format, allowing the Oracle XQuery Virtual Machine to process XML from the database without having to incur the overhead of serializing and parsing the XML in question. The Oracle XQuery Virtual Machine is a powerful XQuery processor currently only available as part of Oracle Database. Enabling a standalone command-line mode allows the Oracle XQuery Virtual Machine to be used to execute XQuery operations in situations when running XQuery inside the database is not appropriate

The first part of this series focuses on architecture, database creation, and the basics of interacting with an Oracle database. After you complete this course, you will be able to:

1. Create a new database
2. Find the files in a database, and identify their purpose
3. Identify the processes that operate on a database
4. Understand the significant memory structures of a database instance
5. Start up and shut down a database

A table is the basic unit of storage in an Oracle database. Without any tables, a database has no value to an enterprise. Regardless of the type of table, data in a table is stored in rows and columns, similar to how data is stored in a spreadsheet. But that is where the similarity ends. The robustness of a database table due to the surrounding reliability, integrity, and scalability of the Oracle database makes a spreadsheet a poor second choice when deciding on a place to store critical information. In this section, we will review the many different types of tables in the Oracle database and how they can satisfy most every data-storage need for an organization.

A relational table is the most common type of table in a database. A relational table is heaporganized; in other words, the rows in the table are stored in no particular order. In the CREATE TABLE command, you can specify the clause ORGANIZATION HEAP to define a heap-organized table, but because this is the default, the clause can be omitted.
Each row of a table contains one or more columns; each column has a datatype and a length. As of Oracle version 8, a column may also contain a user-defined object type, a nested table, or a VARRAY. In addition, a table can be defined as an object table. We will review object tables and objects later in this section.

The whole point of a relational database management system (RDBMS) is to store and supply data to clients who request it. Each RDBMS does this in its own way, so knowing how one works does not necessarily mean that you can figure out the rest. Oracle, being one of the more sophisticated RDBMSs out there, allows for a great deal of flexibility in its configuration and operation. Part of this is possibly due to its architectural design.
The architecture of Oracle is configured in such a way as to ensure that client requests for data retrieval and modification are satisfied efficiently while maintaining database integrity. The architecture also ensures that, should parts of the system become unavailable, mechanisms of the architecture can be used to recover from such failure and, once again, bring the database to a consistent state, ensuring database integrity. Furthermore, the architecture of Oracle needs to provide this capability to many clients at the same time so performance is a consideration when the architecture is configured.
In understanding the Oracle architecture and how it is used to process client requests, several terms need to be introduced. Figure 1-1 displays a diagram of the architectural components that make up a typical Oracle configuration. The terms shown in the diagram and briefly explained below deal with shared memory structures, processes, and datafiles that are used by Oracle. The diagram contains terms that you will read about in this module.

This course, taken in conjunction with the next four courses in the Oracle Database Administration Certification Series, will prepare you for the following Oracle certification exam:

1. 1Z0-052 , Oracle11g: Database Administration
   Oracle Database 12c Administrator Certified Associate

This database administration exam is one of five that you must pass in order to earn certification as an Oracle database administrator.