Oracle DB
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Oracle has evolved from its first release in 1979 to become a leading database with various editions that can be used by individuals, workgroups or enterprises, and it provides developer tools and supports different database structures, security mechanisms, SQL for data access and transactions. Key components of an Oracle database include control files, data files, redo log files, tablespaces that logically organize storage, and various memory and file structures.
Oracle DB
- 1. Introduction to OracleIntroduction to Oracle
- 2. Oracle HistoryOracle History • 1979 Oracle Release 2 • 1986 client/server relational database • 1989 Oracle 6 • 1997 Oracle 8 (object relational) • 1999 Oracle 8i (Java Virtual Machine) • 2000 Oracle Application Server • 2001 Oracle 9i database server • 1979 Oracle Release 2 • 1986 client/server relational database • 1989 Oracle 6 • 1997 Oracle 8 (object relational) • 1999 Oracle 8i (Java Virtual Machine) • 2000 Oracle Application Server • 2001 Oracle 9i database server
- 3. Oracle FamilyOracle Family • Personal Oracle- for single users. Used to develop systems • Oracle Standard Edition- (Entry level Workgroup server) • Oracle Enterprise edition- Extended functionality • Oracle Lite- (Oracle mobile) single users using wireless devices. • Personal Oracle- for single users. Used to develop systems • Oracle Standard Edition- (Entry level Workgroup server) • Oracle Enterprise edition- Extended functionality • Oracle Lite- (Oracle mobile) single users using wireless devices.
- 4. Some Developer ToolsSome Developer Tools • Oracle Forms Developer • Oracle Reports Developer • Oracle Jdeveloper • Oracle Designer • Oracle Forms Developer • Oracle Reports Developer • Oracle Jdeveloper • Oracle Designer
- 10. Database StructureDatabase Structure • Logical structure - maps the data to the Physical structure. • Physical structure -part of the operating system’s file structure. • Memory structure - where all the processing takes place. • Logical structure - maps the data to the Physical structure. • Physical structure -part of the operating system’s file structure. • Memory structure - where all the processing takes place.
- 11. The Logical structuresThe Logical structures • control how the data must be stored in the database. • five Logical structures: – tablespaces – segments – extents – data blocks – schema objects • control how the data must be stored in the database. • five Logical structures: – tablespaces – segments – extents – data blocks – schema objects
- 12. Physical structuresPhysical structures • Parameter files • Password files • Datafiles • Redo log files • Control files • Parameter files • Password files • Datafiles • Redo log files • Control files
- 13. Memory structuresMemory structures • System Global Area (SGA) • Program Global Area (PGA) • The Oracle database uses these memory areas to store information before they are made permanent in the database. • System Global Area (SGA) • Program Global Area (PGA) • The Oracle database uses these memory areas to store information before they are made permanent in the database.
- 14. TableSpacesTableSpaces • A database is divided into logical storage units called Tablespaces. • logical construct for arranging different types of data • An Oracle database must have at least a system tablespace. • It is recommended to have different tablespaces for user and system data. • A database is divided into logical storage units called Tablespaces. • logical construct for arranging different types of data • An Oracle database must have at least a system tablespace. • It is recommended to have different tablespaces for user and system data.
- 15. TablespacesTablespaces • a logical structure• a logical structure Data1 Data2 Data1_01.dbf Data2_01.dbf Data2_02.dbf The DATA1 Tablespace = One datafile The DATA2 Tablespace = Two datafiles
- 16. Create TablespaceCreate Tablespace CREATE TABLESPACE test DATAFILE 'oraservORADATAa.dbf' SIZE 10M AUTOEXTEND ON NEXT 10M MAXSIZE 100M; CREATE TABLE cust(id int,name varchar2(20)) TABLESPACE test; CREATE TABLESPACE test DATAFILE 'oraservORADATAa.dbf' SIZE 10M AUTOEXTEND ON NEXT 10M MAXSIZE 100M; CREATE TABLE cust(id int,name varchar2(20)) TABLESPACE test;
- 17. 7 Logical Tablespaces7 Logical Tablespaces • SYSTEM • DATA • INDEX • USERS • ROLLBACK • TEMP • TOOLS • SYSTEM • DATA • INDEX • USERS • ROLLBACK • TEMP • TOOLS
- 18. Schemas and Schema ObjectsSchemas and Schema Objects • Collection of database objects – Tables – Views – Sequences – Synonyms – Indexes – Procedures – Functions – Packages – Triggers • Collection of database objects – Tables – Views – Sequences – Synonyms – Indexes – Procedures – Functions – Packages – Triggers
- 19. Data BlocksData Blocks • The smallest unit of Input/Output used by Oracle database. • The size of data block for any database is fixed at the time of creation of the database; • Some values of the data block size are 2KB, 8KB, 16KB, and 32KB. • Oracle recommends a size of 8KB • The smallest unit of Input/Output used by Oracle database. • The size of data block for any database is fixed at the time of creation of the database; • Some values of the data block size are 2KB, 8KB, 16KB, and 32KB. • Oracle recommends a size of 8KB
- 20. ExtentsExtents • The next level of data storage. • One extent consists of a specific number of data blocks • One or more extents in turn make up a segment. • When the existing space in a segment is completely used, Oracle allocates a new extent for the segment. • The next level of data storage. • One extent consists of a specific number of data blocks • One or more extents in turn make up a segment. • When the existing space in a segment is completely used, Oracle allocates a new extent for the segment.
- 21. SegmentSegment • A segment consists of a set of extents • Each table’s data is stored in its own single segment. • Each index’s data is stored in a single segment. • More extents are automatically allocated by Oracle to a segment if its existing extents become full. • The different types of segments are the data segments, index segments,rollback segments, and temporary segments. • A segment consists of a set of extents • Each table’s data is stored in its own single segment. • Each index’s data is stored in a single segment. • More extents are automatically allocated by Oracle to a segment if its existing extents become full. • The different types of segments are the data segments, index segments,rollback segments, and temporary segments.
- 22. Physical Database StructurePhysical Database Structure • Password file - which contain the password information for all users. • Parameter file - which contains all the important information necessary to start a database. • Datafiles - which contain the application data being stored, as well as any data necessary to store user-IDs, passwords, and privileges. • Redo log files - which store all the transactions made to the database. These files are also called transaction log files. • Control files - which store information specifying the structure of the database,such as the name and time of creation of the database and the name and location of the datafiles. • Password file - which contain the password information for all users. • Parameter file - which contains all the important information necessary to start a database. • Datafiles - which contain the application data being stored, as well as any data necessary to store user-IDs, passwords, and privileges. • Redo log files - which store all the transactions made to the database. These files are also called transaction log files. • Control files - which store information specifying the structure of the database,such as the name and time of creation of the database and the name and location of the datafiles.
- 23. The Physical files that make up a database Control files Data files Redo Log Files Identify Identify Record changes to
- 24. Control FilesControl Files • Contain a list of all other files in the database • Key information such as – Name of the database – Date created – Current state – Backups performed – Time period covered by redo files • Contain a list of all other files in the database • Key information such as – Name of the database – Date created – Current state – Backups performed – Time period covered by redo files
- 25. • Store a recording of changes made to the database as a result of transactions and internal Oracle Activities • When Oracle fills one redo log, it automatically fills a second. • Used for database recovery • Store a recording of changes made to the database as a result of transactions and internal Oracle Activities • When Oracle fills one redo log, it automatically fills a second. • Used for database recovery Redo Log FilesRedo Log Files
- 26. Security MechanismsSecurity Mechanisms • Database users and schemas • Privileges • Roles • Storage settings and quotas • Resource limits • Auditing • Database users and schemas • Privileges • Roles • Storage settings and quotas • Resource limits • Auditing
- 27. Data Access: SQLData Access: SQL • Data definition language (DDL) statements • Data manipulation language (DML) statements • Transaction control statements • Session control statements • System control statements • Embedded SQL statements • Data definition language (DDL) statements • Data manipulation language (DML) statements • Transaction control statements • Session control statements • System control statements • Embedded SQL statements
- 28. TransactionsTransactions • A transaction is a logical unit of work that comprises one or more SQL statement executed by a single user. According to the ANSI/ISO SQL standard, with which Oracle is compatible, a transaction begins with the user’s first executable SQL statement. A transaction ends when it is explicitly committed or rolled back. • A transaction is a logical unit of work that comprises one or more SQL statement executed by a single user. According to the ANSI/ISO SQL standard, with which Oracle is compatible, a transaction begins with the user’s first executable SQL statement. A transaction ends when it is explicitly committed or rolled back.
Editor's Notes
- #16: Tablespaces A database is divided into logical storage units called tablespaces, which group related logical structures together. For example, tablespaces commonly group all of an application’s objects to simplify some administrative operations. Each database is logically divided into one or more tablespaces. One or more datafiles are explicitly created for each tablespace to physically store the data of all logical structures in a tablespace. The combined size of a tablespace’s datafiles is the total storage capacity of the tablespace (SYSTEM tablespace has 2 MB storage capacity while USERS tablespace has 4 MB). The combined storage capacity of a database’s tablespaces is the total storage capacity of the database (6 MB).
- #24: Datafiles Every Oracle database has one or more physical datafiles. A database’s datafiles contain all the database data. The data of logical database structures such as tables and indexes is physically stored in the datafiles allocated for a database. The characteristics of datafiles are: A datafile can be associated with only one database. Datafiles can have certain characteristics set to allow them to automatically extend when the database runs out of space. One or more datafiles form a logical unit of database storage called a tablespace, as discussed earlier in this chapter.
- #25: Control Files Every Oracle database has a control file. A control file contains entries that specify the physical structure of the database. For example, it contains the following types of information: Database name Names and locations of datafiles and redo log files Time stamp of database creation Like the redo log, Oracle allows the control file to be multiplexed for protection of the control file. The Use of Control Files Every time an instance of an Oracle database is started, its control file is used to identify the database and redo log files that must be opened for database operation to proceed. If the physical makeup of the database is altered (for example, a new datafile or redo log file is created), the control file is automatically modified by Oracle to reflect the change.
- #26: Redo Log Files Every Oracle database has a set of two or more redo log files. The set of redo log files for a database is collectively known as the database’s redo log. A redo log is made up of redo entries (also called redo records), each of which is a group of change vectors describing a single atomic change to the database. The primary function of the redo log is to record all changes made to data. Should a failure prevent modified data from being permanently written to the datafiles, the changes can be obtained from the redo log and work is never lost. Redo log files are critical in protecting a database against failures. To protect against a failure involving the redo log itself, Oracle allows a multiplexed redo log so that two or more copies of the redo log can be maintained on different disks.
- #27: Roles Oracle provides for easy and controlled privilege management through roles. Roles are named groups of related privileges that are granted to users or other roles. A privilege is a right to execute a particular type of SQL statement. Some examples of privileges include the right to: Connect to the database (create a session) Create a table in your schema Select rows from someone else’s table Execute someone else’s stored procedure
- #30: Consider a banking database. When a bank customer transfers money from a savings account to a checking account, the transaction might consist of three separate operations: decrease the savings account, increase the checking account, and record the transaction in the transaction journal. Oracle must guarantee that all three SQL statements are performed to maintain the accounts in proper balance. When something prevents one of the statements in the transaction from executing (such as a hardware failure), the other statements of the transaction must be undone; this is called rolling back. If an error occurs in making either of the updates, then neither update is made.