Each parent record has one or more child records, similar to the structure of a file system. Destructive interactions, which are interactions that incorrectly update data or alter underlying data structures, must be avoided. Oracle significantly hardened the architecture, making it more accessible and easier to set up. An application server contains a large part of the application logic, provides access to the data for the client, and performs some query processing, thus lessening the load on the database. An information system could be a set of cardboard boxes containing manila folders along with rules for how to store and retrieve the folders. The transfer consists of the following separate operations: Record the transaction in the transaction journal. Oracle Database 10g introduced grid computing in 2003. You can use PL/SQL to control the flow of a SQL program, use variables, and write error-handling procedures. In contrast to procedural languages such as C, which describe how things should be done, SQL is nonprocedural and describes what should be done. This chapter contains the following topics: About the Listener and Connection Requests, Understanding Database Server Process Architecture, Understanding Oracle Connection Manager Architecture. and PGA_AGGREGATE_TARGET = n (where n is some amount of memory established by the DBA). The following memory structures are associated with an instance: The SGA is a group of shared memory structures that contain data and control information for one database instance. A table is a set of rows. All applications continue to function after you drop an index. To initiate service registration immediately after the listener is started, use the SQL statement ALTER SYSTEM REGISTER. The instance services applications by allocating other memory areas in addition to the SGA, and starting other processes in addition to background processes. In 1983, RSI became Oracle Systems Corporation and then later Oracle Corporation. A database server also prevents unauthorized access and provides efficient solutions for failure recovery. The database supports many types of schema objects, the most important of which are tables and indexes. A database is divided into logical storage units called tablespaces. For each user connection to the instance, the application is run by a client process. A dispatcher can support multiple client connections concurrently. Also, these systems lacked a simple query language, which hindered application development. Oracle Database can also store program units written in Java. Essential reference manuals in the advanced group include: This manual is the definitive source of information about Oracle SQL. In 1979, RSI introduced Oracle V2 (Version 2) as the first commercially available SQL-based RDBMS, a landmark event in the history of relational databases. Being an Oracle DBA or Oracle APPS DBA you must be knowing the basic of the Database Architecture. In general, a server reliably manages a large amount of data in a multiuser environment so that users can concurrently access the same data. Oracle Net can perform these jobs because it is located on each computer in the network. A PL/SQL procedure or function is a schema object that consists of a set of SQL statements and other PL/SQL constructs, grouped together, stored in the database, and run as a unit to solve a specific problem or to perform a set of related tasks. By Chris Ruel, Michael Wessler . Client applications can send connection requests to the listener, which manages the traffic of these requests to the database server. There are three major structures in Oracle Database server architecture: memory structures, process structures, and storage structures. Today, the most widely accepted database model is the relational model. NOTE:- This posts assumes that you are aware of Oracle Memory Architecture. Every time a client requests a network session with a database, the listener receives the initial request. This registration process is not shown in the figure. An online redo log is made up of redo entries (also called redo records), which record all changes made to data. Additionally, Oracle XML Database (Oracle XML DB) introduced the ability to store and query XML. If a database instance is in restricted mode, then PMON instructs the listener to block all connections to the instance. When applications connect to an Oracle database, they are connected to a database instance. For example, operating system utilities such as the Linux ls and ps can list database files and processes. The server process is not shared by any other client for the duration of the client's session. A virtual circuit is a piece of shared memory used by the dispatcher for client database connection requests and replies. For example, renaming a physical database file does not rename the tables whose data is stored in this file. 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). The Basics of Oracle Architecture As an Oracle DBA, you must be understand the concepts of Oracle architecture clearly. The computer running the RDBMS handles the database server responsibilities while the computers running the applications handle the interpretation and display of data. Each tablespace contains at least one data file. Finally, the listener forwards the connection requests to the gateway process. Each listener is configured with one or more protocol addresses that specify its listening endpoints. The configuration enables the listener to start automatically when the listener fails or is not running. In this case, each statement in a transaction sees data from the same point in time, which is the time at which the transaction began. 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. In this post I would cover the basic Oracle Internal processes and their interprocess communication. In most environments, Oracle processes and client processes run on separate computers. 5Understanding Oracle Net Architecture The Oracle Net listener is an application positioned on top of the Oracle Net foundation layer. Indexes are logically and physically independent of the data. Version 5, released in 1985, supported client/server computing and distributed database systems. A relation is a set of tuples. These files can exist independently of a database instance. A service handler is a dispatcher or a dedicated server process that acts as a connection point to a database. Oracle DBA 11g – Scroll Slides for a Brief Introduction Kernel Training. In his seminal 1970 paper "A Relational Model of Data for Large Shared Data Banks," E. F. Codd defined a relational model based on mathematical set theory. Thus, you can drop and create indexes with no effect on the tables or other indexes. Oracle Net Services supports communications on all major network protocols, including TCP/IP, HTTP, FTP, and WebDAV. The key to adaptability is simplifying the information infrastructure by consolidating information and using automation wherever possible. ... Data Guard architecture and Oracle 12c. Oracle Net provides an architectural solution that allows for greater scalability in Internet and intranet environments. In Oracle Database, a database schema is a collection of logical data structures, or schema objects. 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. In a dedicated server configuration, the listener starts a separate dedicated server process for each incoming client connection request dedicated to servicing the client. ORACLE database is comprised of three types of files. The server process is not shared by any other client. Logical data such as a table is meaningful only for the database. Figure 5-5 illustrates a dedicated server architecture. The advanced guides are too numerous to list in this section. These rules are called integrity constraints. You can call existing PL/SQL programs from Java and Java programs from PL/SQL. Combining the ability to simplify via consolidation and deliver the agility of a service-oriented platform via in-database virtualization, Oracle Database 12c delivers efficiency while improving user service levels. Clients attempting to connect receive one of the following errors: ORA-12526: TNS:listener: all appropriate instances are in restricted mode, ORA-12527: TNS:listener: all appropriate instances are in restricted mode or blocking new connections, ORA-12528: TNS:listener: all appropriate instances are blocking new connections. Depending on the transaction isolation level, this point is the time at which the statement was opened or the time the transaction began. Oracle Version 3, released in 1983, was the first relational database to run on mainframes, minicomputers, and PCs. Technical users who are new to Oracle Database begin by reading one or more manuals in the basic group from cover to cover. Access to the PGA is exclusive to the process. The database receives an initial connection from a client application through the listener. The preceding information enables the listener to direct a client request appropriately. The data of logical database structures, such as tables and indexes, is physically stored in the data files. Oracle Real Application clusters allow multiple instances to access a single database, the instances will be running on multiple nodes. Shared servers place all completed requests into a dispatcher's response queue. This information must be available to those who need it. 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. The manuals in the basic group are closely related, which is reflected in the number of cross-references. Basics of the Oracle Database Architecture. For example, Oracle Database Concepts frequently sends users to a 2 Day manual to learn how to perform a task based on a concept. A table is a two-dimensional representation of a relation in the form of rows (tuples) and columns (attributes). A row identifies a specific employee. Locks help ensure data integrity while allowing maximum concurrent access to data. Oracle Connection Manager is a gateway through which client connection requests are sent either to the next hop or directly to the database server. In general, you give each column a name, a data type, and a width when you create the table. In this post we'll go through the Oracle 12c Architecture … The protocol address defines the protocol the listener listens on and any other protocol specific information. For example, you use SQL to create tables and query and modify data in tables. A PGA is a memory region that contain data and control information for a server or background process. The instance consists of a shared memory area, called the system global area (SGA), and a set of background processes. During registration, the PMON process provides the listener with information about the following: Names of the database services provided by the database, Name of the database instance associated with the services and its current and maximum load, Service handlers (dispatchers and dedicated servers) available for the instance, including their type, protocol addresses, and current and maximum load. When a connection is established, the client and database communicate directly. 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. For example, listening endpoints, such as the port numbers, can be dynamically registered with the listener. 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. This architecture was developed by Oracle with the main goal of database consolidation, so, the multitenant option is useful when you need to have more than one database, for example, if you want or need to have a separate database for each application you … To a new user, the Oracle Database documentation library can seem daunting. The preceding database management systems stored data in rigid, predetermined relationships. An extent is a specific number of logically contiguous data blocks, obtained in a single allocation, used to store a specific type of information. Well well, maybe I should begin with the initial definition by my lecturer… An Oracle database server consists of an Oracle database and an Oracle instance. Because no data definition language existed, changing the structure of the data was difficult. Oracle Database is an RDBMS. The database can also provide read consistency to all queries in a transaction, known as transaction-level read consistency. Table 1-2 lists guides that are used by the majority of expert DBAs and developers at one time or another. One example is a NOT NULL integrity constraint. Figure 5-3 illustrates the role of the listener during the establishment of a connection. Highlights in the evolution of Oracle Database include the following: In 1977, Larry Ellison, Bob Miner, and Ed Oates started the consultancy Software Development Laboratories, which became Relational Software, Inc. (RSI). The two most common database architectures are client/server and multitier. Oracle RAC Architecture. A transaction is a logical, atomic unit of work that contains one or more SQL statements. The current version of Oracle Database is the result of over 30 years of innovative development. SOA services are usually implemented as Web services. Because the physical and logical structures are separate, the physical storage of data can be managed without affecting access to logical storage structures. The figure shows a browser making an HTTP connection and a client making a database connection. Figure 5-6 Oracle Connection Manager Architecture. Start a description with the primary database is easy because it differs very little from any other database you might have. Oracle Basics and Architecture 1. These manuals are intended for expert users who require more detailed information about a particular topic than can be provided by the 2 Day + manuals. Oracle8i was designed for internet computing, enabling the database to be deployed in a multitier environment. For example, after an application queries a table, the database may use an index to find the requested rows, read the data into memory, and perform many other steps before returning a result to the user. Indexes can increase the performance of data retrieval. 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. However, the DBA can let the Oracle DBMS determine the appropriate amount of memory. PL/SQL is integrated with Oracle Database, enabling you to use all of the Oracle Database SQL statements, functions, and data types. The Oracle Net listener is an application positioned on top of the Oracle Net foundation layer. The 2 Day manuals frequently references Oracle Database Concepts for conceptual background about a task. When you execute the SQL command CREATE DATABASE, the following files are created: Every Oracle database has one or more physical data files, which contain all the database data. Oracle Database guarantees that all three operations succeed or fail as a unit. 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. This language enables applications to access the data. 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. Essentially, an RDBMS moves data into a database, stores the data, and retrieves it so that it can be manipulated by applications. 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". Oracle 11g Database - Course uwinpro_training. Scripting on this page enhances content navigation, but does not change the content in any way. 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. This chapter provides an overview of Oracle Database and contains the following sections: Every organization has information that it must store and manage to meet its requirements. A control file contains metadata specifying the physical structure of the database, including the database name and the names and locations of the database files. A tablespace is the logical container for a segment. Présentation Oracle DataBase 11g Cynapsys It Hotspot. A Java stored procedure is a Java method published to SQL and stored in the database for general use. About 22 percent of OCP exam 2 is on material in these areas. Oracle Database = Oracle Instance + Datafiles Again Oracle Instance is nothing but Memory architecture and Background processes. The Enterprise Architecture Blog covers commentary and insights about Cloud and Enterprise Architecture For example, the database must not permit a dirty read, which occurs when one transaction sees uncommitted changes made by another concurrent transaction. You define a table with a table name, such as employees, and set of columns. In Oracle Database, each user must see a consistent view of the data, including visible changes made by a user's own transactions and committed transactions of other users. Basics of Oracle 12c’s Data Guard. Each dispatcher has its own response queue in the SGA. All SQL statements that modify data must proceed with as little interference as possible. A relational database stores data in a set of simple relations. Figure 1-1 shows a database and its instance. The PMON process registers the location and load of the dispatchers with the listener, enabling the listener to forward requests to the least loaded dispatcher. Oracle also focused on the components of the environment that minimize downtime. Version 4 introduced multiversion read consistency. Oracle Database creates and uses memory structures for purposes such as memory for program code, data shared among users, and private data areas for each connected user. Oracle Architecture Basics. For example, if a hardware failure prevents a statement in the transaction from executing, then the other statements must be rolled back. Every Oracle database has a control file. For example, attributes of the employees entity correspond to columns for employee ID and last name. This section discusses logical storage structures. The client sends a connection request to the listener. A relational database is a database that stores data in relations (tables). To understand the Oracle Architecture in detail, we need to have deep understanding of the Memory and Process architecture. A general requirement for a DBMS is to adhere to accepted industry standards for a data access language. What are the components of Physical database structure of Oracle Database? The database consists of both physical structures and logical structures. The following picture illustrates the Oracle Database server architecture. The database was written in C, enabling the database to be ported to multiple platforms. Oracle Database is designed as a multiuser database. 0 Replies Latest reply on Nov 28, 2002 12:58 PM by 161764 Latest reply on Nov 28, 2002 12:58 PM by 161764 These processes consolidate functions that would otherwise be handled by multiple Oracle Database programs running for each client process. Not only are there are over 175 manuals, but many of these manuals are several hundred pages long. This combination of … For example, a security officer will naturally refer to the Oracle Database Security Guide. Integrity rules govern operations on the data and structures of a database. The application architecture refers to the computing environment in which a database application connects to an Oracle database. CMADMIN monitors the state of the gateway processes and the listener, shutting down or starting up processes as needed. 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. Each client connection is bound to a virtual circuit. However, the goal of a DBMS is to reduce wait time so it is either nonexistent or negligible. As shown in Table 1-1, the 2 Day + manuals are divided into manuals for DBAs and developers. When processing a request, the database can use available indexes to locate the requested rows efficiently. Can add components such as employees, and a client process the service handler the. 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