oracle architecture basics

A database is an organized collection of information treated as a unit. The RDBMS stores and retrieves data so that physical operations are transparent to database applications. The next step up from the basic group is the intermediate group. Access to the PGA is exclusive to the process. Because no data definition language existed, changing the structure of the data was difficult. SQL unifies the preceding tasks in one consistent language. A service handler is a dispatcher or a dedicated server process that acts as a connection point to a database. With shared server architectures, client processes ultimately connect to a dispatcher. In addition, it registers the location and load of the gateway processes with the listener, and it answers requests from the Oracle Connection Manager Control utility. An instance is a set of memory structures that manage database files. These processes communicate with client processes and interact with Oracle Database to fulfill requests. A network database is similar to a hierarchical database, except records have a many-to-many rather than a one-to-many relationship. Oracle Database has extended the relational model to an object-relational model, making it possible to store complex business models in a relational database. Technical users who are new to Oracle Database begin by reading one or more manuals in the basic group from cover to cover. Clients configured with a protocol address can send connection requests to the listener. The ORA-12528 error occurs when a database instance is not yet registered with the listener. The only difference is what it does with its archived redo logs. If it allows access, then the listener forwards a request to a gateway process, selecting the one with the fewest connections. Oracle8i Database, released in 1999, provided native support for internet protocols and server-side support for Java. A basic Oracle database system consists of an Oracle database and a database instance. Many other files are important for the functioning of an Oracle database server. Table 1-1 Intermediate Group: 2 Day + Guides, Oracle Database 2 Day + Performance Tuning Guide, Oracle Database 2 Day + Application Express Developer's Guide, Oracle Database 2 Day + Real Application Clusters Guide, Oracle Database 2 Day + Java Developer's Guide, Oracle Database 2 Day + Data Warehousing Guide, Oracle Database 2 Day + .NET Developer's Guide for Microsoft Windows, Oracle Database 2 Day + Data Replication and Integration Guide, Oracle Database 2 Day + PHP Developer's Guide. Using the Server Control (SRVCTL) utility, you can add components such as the listener to an Oracle Restart configuration. For example, a relational database could store information about company employees in an employee table, a department table, and a salary table. Oracle Connection Manager consists of three components: CMADMIN (Oracle Connection Manager Administration). This chapter contains the following topics: About the Listener and Connection Requests, Understanding Database Server Process Architecture, Understanding Oracle Connection Manager Architecture. The maximum size is the block size for the tablespace multiplied by 236, or 128 TB for a 32 KB block size. An extent is a specific number of logically contiguous data blocks, obtained in a single allocation, used to store a specific type of information. One characteristic of an RDBMS is the independence of physical data storage from logical data structures. relational database management system (RDBMS), object-relational database management system (ORDBMS), Oracle Automatic Storage Management (Oracle ASM), Oracle Database Net Services Administrator's Guide, http://www.oracle.com/technetwork/issue-archive/2007/07-jul/o4730-090772.html, Chapter 8, "Server-Side Programming: PL/SQL and Java", "Overview of the Oracle Database Locking Mechanism", Description of "Figure 1-1 Oracle Instance and Database", Chapter 11, "Physical Storage Structures". A database management system (DBMS) is software that controls the storage, organization, and retrieval of data. All operations on the data in an Oracle database are performed using SQL statements. For example, the listener could be configured to listen at the following protocol address: The preceding example shows a TCP/IP address that specifies the host of the listener (sales-server) and a port number (1521). Essentially, an RDBMS moves data into a database, stores the data, and retrieves it so that it can be manipulated by applications. The MULTITENANT architecture was introduced in version 12c and included for the first time in an express edition in version 18c.. Oracle9i Database introduced Oracle RAC in 2001, enabling multiple instances to access a single database simultaneously. However, most companies today use a database to automate their information systems. The relational model has the following major aspects: Well-defined objects store or access the data of a database. Manageability, diagnosability, and availability. Service-oriented architecture (SOA) is a multitier architecture in which application functionality is encapsulated in services. In this case, the RDBMS determines how things should be done and carries out the operation. A general requirement for a DBMS is to adhere to accepted industry standards for a data access language. Also, Version 6 introduced the first version of the PL/SQL language, a proprietary procedural extension to SQL. A table is a two-dimensional representation of a relation in the form of rows (tuples) and columns (attributes). The CMGW process, in turn, forwards the request to another Oracle Connection Manager or directly to the database server, relaying data until the connection terminates. Oracle Net Services is the interface between the database and the network communication protocols that facilitate distributed processing and distributed databases. If a connection to the server already exists, then the gateway multiplexes, or funnels, its connections through the existing connection. Destructive interactions, which are interactions that incorrectly update data or alter underlying data structures, must be avoided. This is Introduction video on Oracle 12C and explaination of Architecture All SQL statements that modify data must proceed with as little interference as possible. Oracle Real Application Clusters (Oracle RAC). Lets start the discussion with Memory architecture first. The manuals in the basic group are closely related, which is reflected in the number of cross-references. Indexes are logically and physically independent of the data. Version 5, released in 1985, supported client/server computing and distributed database systems. Today, the most widely accepted database model is the relational model. The two most common database architectures are client/server and multitier. The figure does not represent all the information that can be registered. For example, a security officer will naturally refer to the Oracle Database Security Guide. This section contains the following topics: Shared server processes are used in the shared server architecture, as shown in Figure 5-4. The advanced guides are too numerous to list in this section. Oracle Basics. A major portion of your understanding of Oracle, both to be a successful Oracle DBA and to be a successful taker of the OCP Exam 2 for Oracle database administration, is understanding the Oracle database architecture. Scripting on this page enhances content navigation, but does not change the content in any way. Oracle Automatic Storage Management (Oracle ASM) helped achieve this goal by virtualizing and simplifying database storage management. The Oracle Net listener is an application positioned on top of the Oracle Net foundation layer. In the strictest sense the terms have the following meanings: A database is a set of files, located on disk, that store data. The data of logical database structures, such as tables and indexes, is physically stored in the data files. A database server also prevents unauthorized access and provides efficient solutions for failure recovery. ORACLE database is comprised of three types of files. 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. Présentation Oracle DataBase 11g Cynapsys It Hotspot. An instance, or database instance, is the combination of memory and processes that are a part of a running installation and a database is a set of files that store data. A transaction is a logical, atomic unit of work that contains one or more SQL statements. These processes consolidate functions that would otherwise be handled by multiple Oracle Database programs running for each client process. Users specify the result that they want (for example, the names of current employees), not how to derive it. Oracle Database is an RDBMS. The Oracle basics section teaches you about how to use SQL to interact with the Oracle database. Memory Structure: Cloud computing basics When a company chooses to “move to the cloud,” it means that its IT infrastructure is stored offsite, at a data center that is maintained by … Oracle Database = Oracle Instance + Datafiles Again Oracle Instance is nothing but Memory architecture and Background processes. A database application is a software program that interacts with a database to access and manipulate data. All memory structures exist in the main memory of the computers that constitute the RDBMS. Physical data is data viewable at the operating system level. An Oracle database uses memory structures and processes to manage and access the database. Enhancements to concurrency control, data distribution, and scalability. This enables the listener to start a dedicated server process when a client request arrives and forward the request to it. The figure shows a browser making an HTTP connection and a client making a database connection. Oracle Version 3, released in 1983, was the first relational database to run on mainframes, minicomputers, and PCs. Basically, there are two main components of Oracle database –– instance and database itself. This registration process is not shown in the figure. The following picture illustrates the Oracle Database server architecture. When a database is started on a database server, Oracle allocates a memory area called the System Global Area (SGA) and starts one or more Oracle processes. Oracle Database can also store program units written in Java. The transfer consists of the following separate operations: Record the transaction in the transaction journal. Chapter 9, "Data Concurrency and Consistency", Oracle Database Advanced Application Developer's Guide to learn about Flashback Query. An RDBMS must be able to group SQL statements so that they are either all committed, which means they are applied to the database, or all rolled back, which means they are undone. Each dispatcher has its own response queue in the SGA. One data block corresponds to a specific number of bytes on disk. Oracle Server: A server is a collection of database units and it provides comprehensive integrated approach to info management; It consists of an "Instance & Database " Oracle Instance: It means to access an oracle database; It always open one & only one database; It consists of two types : - Memory Structure - Back Ground Process. PL/SQL is integrated with Oracle Database, enabling you to use all of the Oracle Database SQL statements, functions, and data types. The database uses a pool of shared processes for multiple sessions. This release enabled organizations to virtualize computing resources by building a grid infrastructure based on low-cost commodity servers. This manual is a task-based database developer quick start guide that explains how to use the basic features of Oracle Database through SQL and PL/SQL. Shared servers place all completed requests into a dispatcher's response queue. It teaches you how to perform all common administrative tasks needed to keep the database operational, including how to perform basic troubleshooting and performance monitoring activities. An idle shared server picks up the virtual circuit from the request queue, services the request, and relinquishes the virtual circuit before attempting to retrieve another virtual circuit from the request queue. A table is a set of rows. Transactions are one of the features that sets Oracle Database apart from a file system. Logic in the transaction began independently of a database management system ( )! Of shared processes for multiple sessions listener parses the client application to a dedicated server process its. 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