Oracle is what type of database

One way to provide such isolation is to shut down the database and reopen it in restricted mode. You could also put the system into quiesced state without disrupting users.

In quiesced state, the database administrator can safely perform certain actions whose executions require isolation from concurrent non-DBA users. Real Application Clusters RAC comprises several Oracle instances running on multiple clustered computers, which communicate with each other by means of a so-called interconnect. RAC uses cluster software to access a shared database that resides on shared disk.

RAC combines the processing power of these multiple interconnected computers to provide system redundancy, near linear scalability, and high availability. RAC also offers significant advantages for both OLTP and data warehouse systems and all systems and applications can efficiently exploit clustered environments. You can scale applications in RAC environments to meet increasing data processing demands without changing the application code.

As you add resources such as nodes or storage, RAC extends the processing powers of these resources beyond the limits of the individual components.

Oracle provides unique portability across all major platforms and ensures that your applications run without modification after changing platforms. This is because the Oracle code base is identical across platforms, so you have identical feature functionality across all platforms, for complete application transparency.

Because of this portability, you can easily upgrade to a more powerful server as your requirements change. People who administer the operation of an Oracle database system, known as database administrators DBAs , are responsible for creating Oracle databases, ensuring their smooth operation, and monitoring their use. In addition to the many alerts and advisors Oracle provides, Oracle also offers the following features:.

Oracle Database provides a high degree of self-management - automating routine DBA tasks and reducing complexity of space, memory, and resource administration. Oracle self-managing database features include the following: automatic undo management, dynamic memory management, Oracle-managed files, mean time to recover, free space management, multiple block sizes, and Recovery Manager RMAN.

Enterprise Manager is a system management tool that provides an integrated solution for centrally managing your heterogeneous environment. Combining a graphical console, Oracle Management Servers, Oracle Intelligent Agents, common services, and administrative tools, Enterprise Manager provides a comprehensive systems management platform for managing Oracle products.

Administer the complete Oracle environment, including databases, i AS servers, applications, and services. Automatic Storage Management automates and simplifies the layout of datafiles, control files, and log files. Database files are automatically distributed across all available disks, and database storage is rebalanced whenever the storage configuration changes.

It provides redundancy through the mirroring of database files, and it improves performance by automatically distributing database files across all available disks. Rebalancing of the database's storage automatically occurs whenever the storage configuration changes.

The Scheduler lets database administrators and application developers control when and where various tasks take place in the database environment. For example, database administrators can schedule and monitor database maintenance jobs such as backups or nightly data warehousing loads and extracts.

Traditionally, the operating systems regulated resource management among the various applications running on a system, including Oracle databases. The Database Resource Manager controls the distribution of resources among various sessions by controlling the exec ution schedule inside the database. By controlling which sessions run and for how long, the Database Resource Manager can ensure that resource distribution matches the plan directive and hence, the business objectives.

In every database system, the possibility of a system or hardware failure always exists. If a failure occurs and affects the database, then the database must be recovered. The goals after a failure are to ensure that the effects of all committed transactions are reflected in the recovered database and to return to normal operation as quickly as possible while insulating users from problems caused by the failure.

Availability of data during backup and recovery operations so users of the system can continue to work. Several circumstances can halt the operation of an Oracle database. The most common types of failure are described in the following table. After an instance failure, Oracle automatically performs instance recovery. If one instance in a RAC environment fails, then another instance recovers the redo for the failed instance.

In a single-instance database, or in a RAC database in which all instances fail, Oracle automatically applies all redo when you restart the database. Different files can be affected by this type of disk failure, including the datafiles, the redo log files, and the control files. Also, because the database instance cannot continue to function properly, the data in the database buffers of the system global area cannot be permanently written to the datafiles.

A disk failure requires you to restore lost files and then perform media recovery. Unlike instance recovery, media recovery must be initiated by the user.

Media recovery updates restored datafiles so the information in them corresponds to the most recent time point before the disk failure, including the committed data in memory that was lost because of the failure. Oracle provides for complete media recovery from all possible types of hardware failures, including disk failures. Options are provided so that a database can be completely recovered or partially recovered to a specific point in time.

If some datafiles are damaged in a disk failure but most of the database is intact and operational, the database can remain open while the required tablespaces are individually recovered. Therefore, undamaged portions of a database are available for normal use while damaged portions are being recovered.

Oracle uses several structures to provide complete recovery from an instance or disk failure: the redo log , undo records , a control file , and database backups.

The redo log is a set of files that protect altered database data in memory that has not been written to the datafiles. The redo log can consist of the online redo log and the archived redo log. The online redo log is a set of two or more online redo log files that record all changes made to the database, including uncommitted and committed changes.

Redo entries are temporarily stored in redo log buffers of the system global area, and the background process LGWR writes the redo entries sequentially to an online redo log file. LGWR writes redo entries continually, and it also writes a commit record every time a user process commits a transaction. Optionally, filled online redo files can be manually or automatically archived before being reused, creating archived redo logs.

To enable or disable archiving, set the database in one of the following modes:. The database can also be backed up while it is open and available for use.

However, additional administrative operations are required to maintain the archived redo log. Also, the database can be backed up only while it is completely closed. Because no archived redo log is created, no extra work is required by the database administrator.

Undo records are stored in undo tablespaces. Oracle uses the undo data for a variety of purposes, including accessing before-images of blocks changed in uncommitted transactions. During database recovery, Oracle applies all changes recorded in the redo log and then uses undo information to roll back any uncommitted transactions. The control files include information about the file structure of the database and the current log sequence number being written by LGWR.

During normal recovery procedures, the information in a control file guides the automatic progression of the recovery operation. Because one or more files can be physically damaged as the result of a disk failure, media recovery requires the restoration of the damaged files from the most recent operating system backup of a database. RMAN is an Oracle utility that manages backup and recovery operations, creates backups of database files datafiles, control files, and archived redo log files , and restores or recovers a database from backups.

Oracle Database Administrator's Guide for more information about managing undo space. Computing environments configured to provide nearly full-time availability are known as high availability systems. Such systems typically have redundant hardware and software that makes the system available despite failures. Well-designed high availability systems avoid having single points-of-failure.

When failures occur, the fail over process moves processing performed by the failed component to the backup component. This process remasters systemwide resources, recovers partial or failed transactions, and restores the system to normal, preferably within a matter of microseconds. The more transparent that fail over is to users, the higher the availability of the system. Oracle has a number of products and features that provide high availability in cases of unplanned downtime or planned downtime.

These can be used in various combinations to meet specific high availability needs. A data warehouse is a relational database designed for query and analysis rather than for transaction processing. It usually contains historical data derived from transaction data, but it can include data from other sources. It separates analysis workload from transaction workload and enables an organization to consolidate data from several sources. In addition to a relational database, a data warehouse environment includes an extraction, transportation, transformation, and loading ETL solution, an online analytical proce ssing O LAP engine, client analysis tools, and other applications that manage the process of gathering data and delivering it to business users.

You must load your data warehouse regularly so that it can serve its purpose of facilitating business analysis. To do this, data from one or more operational systems must be extracted and copied into the warehouse. The process of extracting data from source systems and bringing it into the data warehouse is commonly called ETL , which stands for extraction, transformation, and loading. A materialized view provides access to table data by storing the results of a query in a separate schema object.

Unlike an ordinary view, which does not take up any storage space or contain any data, a materialized view contains the rows resulting from a query against one or more base tables or views. A materialized view can be stored in the same database as its base tables or in a different database. Materialized views stored in the same database as their bas e tables can improve query performance through query rewrites.

Query rewrite is a mechanism where Oracle or applications from the end user or database transparently improve query response time, by automatically rewriting the SQL query to use the materialized view instead of accessing the original tables.

Query rewrites are particularly useful in a data warehouse environment. Data warehousing environments typically have large amounts of data and ad hoc queries, but a low level of concurrent database manipulation language DML transactions. For such applications, bitmap indexing provides:. Dramatic performance gains even on hardware with a relatively small number of CPUs or a small amount of memory.

Fully indexing a large table with a traditional B-tree index can be prohibitively expensive in terms of space because the indexes can be several times larger than the data in the table. Bitmap indexes are typically only a fraction of the size of the indexed data in the table.

To reduce disk use and memory use specifically, the buffer cache , you can store tables and partitioned tables in a compressed format inside the database.

This often leads to a better scaleup for read-only operations. Table compression can also speed up query execution. There is, however, a slight cost in CPU overhead.

By dividing the work necessary to run a statement among multiple processes, Oracle can run the statement more quickly than if only a single process ran it. This is called parallel execution or parallel processing. Parallel execution dramatically reduces response time for data-intensive operations on large databases, because statement processing can be split up among many CPUs on a single Oracle system.

Oracle has many SQL operations for performing analytic operations in the database. These include ranking, moving averages, cumulative sums, ratio-to-reports, and period-over-period comparisons. For additional analytic functionality, Oracle OLAP provides multidimensional calculations, forecasting, modeling, and what-if scenarios. This enables developers to build sophisticated analytic and planning applications such as sales and marketing analysis, enterprise budgeting and financial analysis, and demand planning systems.

Data can be stored in either relational tables or multidimensional objects. Oracle OLAP provides the query performance and calculation capability previously found only in multidimensional databases to Oracle's relational platform. Instead, it is truly an OLAP-enabled relational database. As a result, Oracle provides the benefits of a multidimensional database along with the scalability, accessibility, security, manageability, and high availability of the Oracle database.

With Oracle Data Mining, data never leaves the database — the data, data preparation, model building, and model scoring results all remain in the database. This enables Oracle to provide an infrastructure for application developers to integrate data mining seamlessly with database applications. Some typical examples of the applications that data mining are used in are call centers, ATMs, ERM, and business planning applications.

Data mining functions such as model building, testing, and scoring are provided through a Java API. Partitioning addresses key issues in supporting very large tables and indexes by letting you decompose them into smaller and more manageable pieces called partitions. However, after partitions are defined, DDL statements can access and manipulate individuals partitions rather than entire tables or indexes. This is how partitioning can simplify the manageability of large database objects. Also, partitioning is entirely transparent to applications.

Partitioning is useful for many different types of applications, particularly applications that manage large volumes of data. OLTP systems often benefit from improvements in manageability and availability, while data warehousing systems benefit from performance and manageability. Oracle includes datatypes to handle all the types of rich Internet content such as relational data, object-relational data, XML, text, audio, video, image, and spatial.

These datatypes appear as native types in the database. They can all be queried using SQL. A single SQL statement can include data belonging to any or all of these datatypes. Each consists of a standards-based set of components, tools, and utilities. They provide efficient, random, piece-wise access to the data.

Oracle Text indexes any document or textual content to add fast, accurate retrieval of information. Oracle Text allows text searches to be combined with regular database searches in a single SQL statement. The ability to find documents based on their textual content, metadata, or attributes, makes the Oracle Database the single point of integration for all data management.

Oracle Ultra Search lets you index and search Web sites, database tables, files, mailing lists, Oracle Application Server Portals, and user-defined data sources. As such, you can use Oracle Ultra Search to build different kinds of search applications. Oracle inter Media provides an array of services to develop and deploy traditional, Web, and wireless applications that include image, audio, and video in an integrated fashion. Multimedia content can be stored and managed directly in Oracle, or Oracle can store and index metadata together with external references that enable efficient access to media content stored outside the database.

Oracle includes built-in spatial features that let you store, index, and manage location content assets, buildings, roads, land parcels, sales regions, and so on. The Oracle Spatial Option adds advanced spatial features such as linear reference support and coordinate systems.

Oracle includes security features that control how a database is accessed and used. For example, security mechanisms:. Associated with each database user is a schema by the same name. By default, each database user creates and has access to all objects in the corresponding schema.

Database security can be classified into two categories: system security and data security. System security includes the mechanisms that control the access and use of the database at the system level.

For example, system security includes:. System security mechanisms check whether a user is authorized to connect to the database, whether database auditing is active, and which system operations a user can perform.

Data security includes the mechanisms that control the access and use of the database at the schema object level. For example, data security includes:. The Oracle database provides discretionary access control , which is a means of restricting access to information based on privileges.

The appropriate privilege must be assigned to a user in order for that user to access a schema object. Appropriately privileged users can grant other users privileges at their discretion. Authentication to validate the identity of the entities using your networks, databases, and applications.

Authorization processes to limit access and actions, limits that are linked to user's identities and roles. Data must adhere to certain business rules, as determined by the database administrator or application developer. Oracle provides integrity constraints and database triggers to manage data integrity rules. An integrity constraint is a declarative way to define a business rule for a column of a table.

An integrity constraint is a statement about table data that is always true and that follows these rules:. If an integrity constraint is created for a table and some existing table data does not satisfy the constraint, then the constraint cannot be enforced.

After a constraint is defined, if any of the results of a DML statement violate the integrity constraint, then the statement is rolled back, and an error is returned. Integrity constraints are defined with a table and are stored as part of the table's definition in the data dictionary, so that all database applications adhere to the same set of rules. When a rule changes, it only needs be changed once at the database level and not many times for each application.

The following integrity constraints are supported by Oracle:. Key is used in the definitions of several types of integrity constraints. A key is the column or set of columns included in the definition of certain types of integrity constraints. Keys describe the relationships between the different tables and columns of a relational database. Individual values in a key are called key values.

A primary key's values uniquely identify the rows in a table. Only one primary key can be defined for each table. Foreign key: The column or set of columns included in the definition of a referential integrity constraint. Referenced key: The unique key or primary key of the same or a different table referenced by a foreign key.

Triggers supplement the standard capabilities of Oracle to provide a highly customized database management system. For example, a trigger can restrict DML operations against a table to those issued during regular business hours. A distributed environment is a network of disparate systems that seamlessly communicate with each other. Each system in the distributed environment is called a node. The system to which a user is directly connected is called the local system. Any additional systems accessed by this user are called remote systems.

A distributed environment allows applications to access and exchange data from the local and remote systems. All the data can be simultaneously accessed and modified. A homogeneous distributed database system is a network of two or more Oracle databases that reside on one or more computers.

Distributed SQL enables applications and users to simultaneously access or modify the data in several databases as easily as they access or modify a single database. An Oracle distributed database system can be transparent to users, making it appear as though it is a single Oracle database.

Companies can use this distributed SQL feature to make all its Oracle databases look like one and thus reduce some of the complexity of the distributed system. Oracle uses database links to enable users on one database to access objects in a remote database.

A local user can access a link to a remote database without having to be a user on the remote database. Location transparency occurs when the physical location of data is transparent to the applications and users. For example, a view that joins table data from several databases provides location transparency because the user of the view does not need to know from where the data originates. Oracle's provides query, update, and transaction transparency.

Oracle ensures the integrity of data in a distributed transaction using the two-phase commit mechanism. Distributed query optimization reduces the amount of data transfer required between sites when a transaction retrieves data from remote tables referenced in a distributed SQL statement. Oracle Streams enables the propagation and management of data, transactions, and events in a data stream either within a database, or from one database to another.

The stream routes published information to subscribed destinations. As users' needs change, they can simply implement a new capability of Oracle Streams, without sacrificing existing capabilities. Oracle Streams provides a set of elements that lets users control what information is put into a stream, how the stream flows or is routed from node to node, what happens to events in the stream as they flow into each node, and how the stream terminates.

By specifying the configuration of the elements acting on the stream, a user can address specific requirements, such as message queuing or data replication. Oracle Streams implicitly and explicitly captures events and places them in the staging area.

Sophisticated subscription rules can determine what events should be captured. The staging area is a queue that provides a service to store and manage captured events. Changes to database tables are formatted as logical change records LCR , and stored in a staging area until subscribers consume them. Messages in a staging area are consumed by the apply engine, where changes are applied to a database or consumed by an application. A flexible apply engine allows use of a standard or custom apply function.

Support for explicit dequeue lets application developers use Oracle Streams to reliably exchange messages. They can also notify applications of changes to data, by still leveraging the change capture and propagation features of Oracle Streams.

It provides a unified framework for processing events. Events generated in applications, in workflow, or implicitly captured from redo logs or database triggers can be captured in a queue. These events can be consumed in a variety of ways. They can be automatically applied with a user-defined function or database table operation, can be explicitly dequeued, or a notification can be sent to the consuming application.

These events can be transformed at any stage. If the consuming application is on a different database, then the events are automatically propagated to the appropriate database. Operations on these events can be automatically audited, and the history can be retained for the user-specified duration. Replication is the maintenance of database objects in two or more databases.

Oracle Streams provides powerful replication features that can be used to keep multiple copies of distributed objects synchronized. Oracle Streams automatically determines what information is relevant and shares that information with those who need it. This active sharing of information includes capturing and managing events in the database including data changes with DML and propagating those events to other databases and applications.

Data changes can be applied directly to the replica database, or can call a user-defined procedure to perform alternative work at the destination database, for example, populate a staging table used to load a data warehouse. Oracle Streams is an open information sharing solution, supporting heterogeneous replication between Oracle and non-Oracle systems. Using a transparent gateway, DML changes initiated at Oracle databases can be applied to non-Oracle platforms.

Oracle Streams is fully inter-operational with materialized views, or snapshots, which can maintain updatable or read-only, point-in-time copies of data. They can contain a full copy of a table or a defined subset of the rows in the master table that satisfy a value-based selection criterion.

There can be multitier materialized views as well, where one materialized view is a subset of another materialized view. Materialized views are periodically updated, or refreshed, from their associated master tables through transactionally consistent batch updates.

Oracle can work with non-Oracle data sources, non-Oracle message queuing systems, and non-SQL applications, ensuring interoperability with other vendor's products and technologies.

They translate third party SQL dialects, data dictionaries, and datatypes into Oracle formats, thus making the non-Oracle data store appear as a remote Oracle database. These technologies enable companies to seamlessly integrate the different systems and provide a consolidated view of the company as a whole. Introducing a Transparent Gateway into an Oracle Streams environment enables replication of data from an Oracle database to a non-Oracle database.

Generic Connectivity is a generic solution, while Oracle Transparent Gateways are tailored solutions, specifically coded for the non-Oracle system.

It is a simple, widely understood, unified data model. SQL databases are relational databases, which means that data is stored in a set of simple relations. All operations on the information in an Oracle database are performed using SQL statements. A statement must be the equivalent of a complete SQL sentence, as in:. Only a complete SQL statement can run successfully. A sentence fragment, such as the following, generates an error indicating that more text is required:.

A SQL statement can be thought of as a very simple, but powerful, computer program or instruction. SQL statements are divided into the following categories:.

These statements create, alter, maintain, and drop schema objects. DDL statements also include statements that permit a user to grant other users the privileges to access the database and specific objects within the database. These statements manipulate data. For example, querying, inserting, updating, and deleting rows of a table are all DML operations.

These statements manage the changes made by DML statements. They enable a user to group changes into logical transactions. These statements let a user control the properties of the current session, including enabling and disabling roles and changing language settings.

These statements change the properties of the Oracle database instance. It lets users change settings, such as the minimum number of shared servers, kill a session, and perform other tasks. These statements incorporate DDL, DML, and transaction control statements in a procedural language program, such as those used with the Oracle precompilers.

Network traffic between applications and the database is reduced, so application and system performance increases. They are created and stored in compiled form in the database and can be run by a user or a database application. Procedures and functions are identical, except that functions always return a single value to the user. Procedures do not return values.

Packages encapsulate and store related procedures, functions, variables, and other constructs together as a unit in the database. They offer increased functionality for example, global package variables can be declared and used by any procedure in the package. They also improve performance for example, all objects of the package are parsed, compiled, and loaded into memory once.

Java is an object-oriented programming language efficient for application-level programs. Java Stored Procedures are portable and secure in terms of access control, and allow non-Java and legacy applications to transparently invoke Java. The entire functionality of the database is available in all the languages. All language-specific standards are supported. Developers can choose the languages in which they are most proficient or one that is most suitable for a specific task.

It supports the entire Oracle Database feature set. OCI provides powerful functionality to build high performance, secure, scalable, and fault-tolerant applications. OCI is also used within the server for the data access needs of database kernel components, along with distributed database access.

OCI lets an application developer use C function calls to access the Oracle data server and control all phases of business logic execution. OCI is exposed as a library of standard database access and retrieval functions in the form of a dynamic runtime library that can be linked in by the application. In conjunction with an ODBC driver, an application can access any data source including data stored in spreadsheets, like Excel.

Oracle also provides. A transaction is a logical unit of work that comprises one or more SQL statements run by a single user. A transaction ends when it is explicitly committed or rolled back by that user. Transactions let users guarantee consistent changes to data, as long as the SQL statements within a transaction are grouped logically. A transaction should consist of all of the necessary parts for one logical unit of work—no more and no less.

Data in all referenced tables are in a consistent state before the transaction begins and after it ends. Transactions should consist of only the SQL statements that make one consistent change to the data. Consider a banking database. When a bank customer transfers money from a savings account to a checking account, the transaction can consist of three separate operations: decrease the savings account, increase the checking account, and record the transaction in the transaction journal. The transfer of funds the transaction includes increasing one account one SQL statement , decreasing another account one SQL statement , and recording the transaction in the journal one SQL statement.

All actions should either fail or succeed together; the credit should not be committed without the debit. Oracle, it is essential to understand the strengths and weaknesses of each tool as it relates to your desired business outcomes. Oracle is a ubiquitous choice with the Fortune list of companies and larger enterprises, as it is designed for large business applications and large data warehouses. Those looking for the most extensive list of features will choose Oracle because it is packed with features and minimizes the need for third-party software.

MySQL provides a better choice for projects on a smaller scale. By migrating database-driven applications to MySQL, or using MySQL for new development projects, corporations are realizing cost savings that many times stretch into hundreds of thousands of dollars. For startups and smaller companies, MySQL fits better. No matter which database you choose, every business can benefit from integrated data without having to invest in hardware, software, or related personnel.

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It is free and open-source. It is licensed under the GNU. A database is divided into logical storage units called tablespaces. A tablespace is the logical container for a segment.

Each tablespace consists of at least one data file. An Oracle database uses memory structures and processes to manage and access the database.

When applications connect to an Oracle database, they connect to a database instance. The instance services applications by allocating other memory areas in addition to the SGA, and starting other processes in addition to background processes. A process is a mechanism in an operating system that can run a series of steps. Some operating systems use the terms job , task , or thread.

For the purposes of this topic, a thread is equivalent to a process. An Oracle database instance has the following types of processes:. These processes are created and maintained to run the software code of an application program or an Oracle tool. Most environments have separate computers for client processes.

These processes consolidate functions that would otherwise be handled by multiple Oracle Database programs running for each client process. These processes communicate with client processes and interact with Oracle Database to fulfill requests. Oracle processes include server processes and background processes. In most environments, Oracle processes and client processes run on separate computers. Oracle Database creates and uses memory structures for program code, data shared among users, and private data areas for each connected user.

The SGA is a group of shared memory structures that contain data and control information for one database instance. Starting in Oracle Database 12 c Release 1 A PGA is a memory region that contains data and control information for a server or background process.

Access to the PGA is exclusive to the process. Each server process and background process has its own PGA. To take full advantage of a given computer system or network, Oracle Database enables processing to be split between the database server and the client programs. The computer running the RDBMS handles the database server responsibilities while the computers running the applications handle the interpretation and display of data.

The application architecture is the computing environment in which a database application connects to an Oracle database. The server runs Oracle Database software and handles the functions required for concurrent, shared data access.

The server receives and processes requests that originate from clients. In a traditional multitier architecture , one or more application servers perform parts of the operation. An application server contains a large part of the application logic, provides access to the data for the client, and performs some query processing. In this way, the load on the database decreases.

The application server can serve as an interface between clients and multiple databases and provide an additional level of security. A service-oriented architecture SOA is a multitier architecture in which application functionality is encapsulated in services. SOA services are usually implemented as Web services. Oracle Net Services is the interface between the database and the network communication protocols that facilitate distributed processing and distributed databases.

Communication protocols define the way that data is transmitted and received on a network. Oracle Net , a component of Oracle Net Services, establishes and maintains a network session from a client application to a database server. After a network session is established, Oracle Net acts as the data courier for both the client application and the database server, exchanging messages between them.

Oracle Net can perform these jobs because it is located on each computer in the network. An important component of Net Services is the Oracle Net Listener called the listener , which is a process that runs on the database or elsewhere in the network. Client applications send connection requests to the listener, which manages the traffic of these requests to the database.

When a connection is established, the client and database communicate directly. Each client process connects to a dedicated server process. The server process is not shared by any other client for the duration of the client's session. Each new session is assigned a dedicated server process. The database uses a pool of shared server processes for multiple sessions.

A client process communicates with a dispatcher , which is a process that enables many clients to connect to the same database instance without the need for a dedicated server process for each client. Starting in Oracle Database 12 c , the multitenant architecture enables an Oracle database to be a multitenant container database CDB.

A CDB is a single physical database that contains zero, one, or many user-created pluggable databases. By consolidating multiple physical databases on separate computers into a single database on a single computer, the multitenant architecture provides the following benefits:.

Figure shows two separate non-CDBs: hr and sales. Each non-CDB has its own memory and set of database files, and resides on its own computer. Each non-CDB has its own dedicated user application.

As shown in Figure , these PDBs appear to their respective applications just as they did before database consolidation. This manual assumes the architecture of a non-CDB unless otherwise indicated. To a new user, the Oracle Database documentation library can seem daunting. Not only are there are over manuals, but many of these manuals are several hundred pages long.

However, the documentation is designed with specific access paths to ensure that users are able to find the information they need as efficiently as possible. The documentation set is divided into three layers or groups: basic, intermediate, and advanced. Technical users who are new to Oracle Database begin by reading one or more manuals in the basic group from cover to cover.

Each manual in this group is designed to be read in two days. The manual teaches DBAs how to perform all typical administrative tasks needed to keep the database operational, including how to perform basic troubleshooting and performance monitoring activities. Oracle Database 2 Day Developer's Guide. The manuals in the basic group are closely related, which is reflected in the number of cross-references.

For example, Oracle Database Concepts frequently sends users to a 2 Day manual to learn how to perform a task based on a concept. The 2 Day manuals frequently reference Oracle Database Concepts for conceptual background about a task. Oracle Database Reference. The manual is the definitive source of information about initialization parameters, data dictionary views, and dynamic performance views. The advanced guides are too numerous to list in this section. Table lists guides that the majority of expert DBAs and developers use.

Oracle Database Development Guide. Other advanced guides required by a particular user depend on the area of responsibility of this user. For example, a security officer naturally refers to the Oracle Database Security Guide. About Relational Databases Every organization has information that it must store and manage to meet its requirements.

Repository of metadata This repository is usually called a data dictionary. Query language This language enables applications to access the data. The first generation of database management systems included the following types: Hierarchical A hierarchical database organizes data in a tree structure.

Network A network database is similar to a hierarchical database, except records have a many-to-many rather than a one-to-many relationship. The relational model has the following major aspects: Structures Well-defined objects store or access the data of a database. Operations Clearly defined actions enable applications to manipulate the data and structures of a database. Integrity rules Integrity rules govern operations on the data and structures of a database. An RDBMS distinguishes between the following types of operations: Logical operations In this case, an application specifies what content is required.

Brief History of Oracle Database The current version of Oracle Database is the result of over 35 years of innovative development. Portable version of Oracle Database Oracle Version 3, released in , was the first relational database to run on mainframes, minicomputers, and PCs. Enhancements to concurrency control, data distribution, and scalability Version 4 introduced multiversion read consistency. Objects and partitioning Oracle8 was released in as the object-relational database, supporting many new data types.

Internet computing Oracle8 i Database, released in , provided native support for internet protocols and server-side support for Java. Grid computing Oracle Database 10 g introduced grid computing in Manageability, diagnosability, and availability Oracle Database 11 g , released in , introduced a host of new features that enabled administrators and developers to adapt quickly to changing business requirements.

See Also: " Introduction to Schema Objects ". Tables A table describes an entity such as employees. You define a table with a table name, such as employees , and set of columns. In general, you give each column a name, a data type , and a width when you create the table.

Indexes An index is an optional data structure that you can create on one or more columns of a table. See Also: " Introduction to Indexes ". See Also: " SQL ". Transaction Management Oracle Database is designed as a multiuser database.