Oracle Database Workshop 1 Presented to IBRI CAS 27-Nov-2011 By Abdullah Alkalbani

Workshop Objectives Describe Oracle Database (10g). Identify high-level architectural components of an Oracle Database. Identify Oracle Database internal data structures. Define the mechanisms used when processing Insert/Update/Delete statements. Describe DBMS programs used with Oracle Database.

10g provides better ways to administer your database. “It takes the mountain out of the mole hill”.

9i Mountains = More effort and resources to accomplish similar tasks in 10g 10g Mole Hills = Less effort and resources to accomplish similar tasks in 9i.

Popular Features Automatic Shared Memory Management (ASMM) Data Pump SQL Tuning Advisor Flashback Database RMAN - Backupset Compression

Most people call it a “Database” Technically an Oracle Database is broken into two high-level components 1.INSTANCE – Non-persistent, memory- based processes and structures 2.DATABASE – Persistent, disk-based data and control files

So Why Differentiate? Most Oracle installations consist of only a single “Instance” and single “Database”… Instance Database

Oracle RAC is Different Oracle “Real Application Clusters” allow multiple “Instances” to interact with a single “Database” to provide high availability… Instance 1 Database Instance 3Instance 2

“Instance” a Little Closer An Oracle Instance… –Is a means to access an Oracle Database –Always opens one and only one Database –Consists of memory and background process structures

Picture of an “Instance” Instance Library Cache Data Dictionary Cache Shared Pool SGA Database Buffer Cache Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Memory Structures Back- Ground Processes

“Database” a Little Closer An Oracle Database… –Is a collection of data that is treated as a unit –Consists of three file types

Picture of a “Database” Archived Log Files Parameter File Password File Oracle Database Data Files Control Files Redo Log Files

Picture of an “Instance” Instance Library Cache Data Dictionary Cache Shared Pool SGA Database Buffer Cache Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Memory Structures Back- Ground Processes

Memory Structure Oracle’s memory structure consists of two memory areas known as: 1.System Global Area (SGA): Allocated at instance start up, and is a fundamental component of an Oracle Instance 2.Program Global Area (PGA): Allocated when the server process is started

System Global Area The SGA consists of several memory structures: –Shared Pool –Database Buffer Cache –Redo Log Buffer –Other structures There are two additional memory structures that can be configured within the SGA: –Large Pool –Java Pool

System Global Area The size of the SGA is determined by the parameters that set the sizes of the various pools; these parameters are dynamic The SGA_MAX_SIZE parameter sets the maximum size of the SGA (so you can limit it) and is not a dynamic parameter Thanks Ned!

Picture of an “Instance” Instance Library Cache Data Dictionary Cache Shared Pool SGA Database Buffer Cache Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Memory Structures Back- Ground Processes

Shared Pool Used to store: –Most recently executed SQL statements –Most recently used data definitions It consists of two key performance-related memory structures: –Library Cache –Data Dictionary Cache Sized by the parameter SHARED_POOL_SIZE

Library Cache Stores information about the most recently used SQL and PL/SQL statements Enables the sharing of commonly used statements Is managed by a least recently used (LRU) algorithm Consists of two structures –Shared SQL area –Shared PL/SQL area Size is determined by the Shared Pool sizing

Picture of an “Instance” Instance Library Cache Data Dictionary Cache Shared Pool SGA Database Buffer Cache Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Memory Structures Back- Ground Processes

Data Dictionary Cache A collection of the most recently used definitions in the database Includes information about database files, tables, indexes, columns, users, privileges, and other database objects During the parse phase, the server process looks at the data dictionary for information to resolve object names and validate access

Database Buffer Cache Stores copies of data blocks that have been retrieved from the data files Enables great performance gains when you obtain and update data Managed through an LRU algorithm DB_BLOCK_SIZE determines primary block size

Picture of an “Instance” Instance Library Cache Data Dictionary Cache Shared Pool SGA Database Buffer Cache Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Memory Structures Back- Ground Processes

Redo Log Buffer Records all changes made to the database data blocks Primary purpose is recovery Changes recorded within are called redo entries Redo entries contain information to reconstruct or redo changes Size defined by LOG_BUFFER

Large Pool An optional area of memory in the SGA Relieves the burden place on the Shared Pool Used for: –Session memory for the Shared Server –I/O server processes –Backup and restore operations for RMAN Does not use an LRU list Sized by LARGE_POOL_SIZE Can be dynamically resized

Java Pool Services parsing requirements for Java commands Required if installing and using Java Sized by JAVA_POOL_SIZE parameter

Oracle “Process” Structure Oracle takes advantage of various types of Processes: –User Process: Started at the time a database user requests connection to the Oracle Server –Server Process: Connects to the Oracle instance and is started when a user establishes a session –Background Processes: Started when an Oracle instance is started

User Process A program that requests interaction with the Oracle server Must first establish a connection Does not interact directly with the Oracle server Server Process User Process Connection Established

Server Process A program that directly interacts with the Oracle server Fulfills calls generated and returns results Can be dedicated or shared server

Picture of an “Instance” Instance Library Cache Data Dictionary Cache Shared Pool SGA Database Buffer Cache Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Memory Structures Back- Ground Processes

Background Processes Maintains and enforces relationships between physical and memory structures –Mandatory background processes: DBWnPMONCKPT LGWRSMON –Optional background processes: ARCnLMDnQMNn CJQ0LMONRECO DnnnLMSSnnn LCKnPnnn

Database Writer (DBWn) DBWn writes when: Checkpoint occurs Dirty buffers reach threshold There are no free buffers Timeout occurs Tablespace OFFLINE Tablespace READ ONLY Table DROP or TRUNCATE Tablespace BEGIN BACKUP Oracle Database Data Files Control Files Redo Log Files Instance Shared Pool Library Cache Data Dictionary Cache SGA Database Buffer Cache Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Shared Pool

Log Writer (LGWR) LGWR writes: At commit When one-third full When there is 1 MB of redo Every three seconds Before DBWn writes Instance Shared Pool Library Cache Data Dictionary Cache SGA Database Buffer Cache Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Oracle Database Data Files Control Files Redo Log Files

System Monitor (SMON) Responsibilities: Instance recovery –Rolls forward changes in online redo log files –Opens database for user access –Rolls back uncommitted transactions Coalesces free space Deallocates temporary segments Oracle Database Data Files Control Files Redo Log Files Instance Shared Pool Library Cache Data Dictionary Cache SGA Database Buffer Cache Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Shared Pool

Process Monitor (PMON) Cleans up after failed processes by: Rolling back the transaction Releasing locks Releasing other resources Restarting dead dispactchers Database Buffer Cache Oracle Database Data Files Control Files Redo Log Files Instance Shared Pool Library Cache Data Dictionary Cache SGA Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Shared Pool

Checkpoint (CKPT) Responsible for: Signaling DBWn at checkpoints Updating datafile headers with checkpoint information Updating control files with checkpoint information Instance Shared Pool Library Cache Data Dictionary Cache SGA Database Buffer Cache Redo Log Buffer Java PoolLarge Pool PMONSMONDBWRLGWRCKPTOthers Oracle Database Data Files Control Files Redo Log Files Shared Pool

Archiver (ARCn) Optional background process Automatically archives online redo log files when ARCHIVELOG mode is set Preserves the record of all changes made to the database Oracle Database Data Files Control Files Redo Log Files Archived Logs ARCn

Oracle Data Storage Oracle keeps all system and user data in two basic storage containers: 1.Tablespace… a logical entity known only to Oracle 2.Data Files… physical files that may (typically) be seen from the operating system

Tablespaces Can belong to only one database at a time Consist of one or more data files Are further divided into logical units of store

Data Files Can belong to only one tablespace and one database Are a repository for schema object data Data File Database Tablespace

2 Types of Tablespace 1.Tablespaces required by Oracle for normal operations 2.Tablespaces that contain data and indexes that support your applications

Required Tablespaces System – Contains the Oracle Data Dictionary Sysaux - New to 10g; supports historic monitoring / tuning Temporary – Used for disk-based sorting of data (select...from…order by) Undo – Used for transaction consistency during Insert / Update / Delete statements

SQL Statements (IUDS) Insert Update Delete Select What happens when someone connects to the database and issues one of these statements?

Connect to Oracle – What Happens Server Process User Process Connect User/Pwd Are “User” definition and privileges in SGA “Dictionary Cache”? –If not, try to fetch from the “System” tablespace –If there, validate Pwd and privileges to login –Allow connection if all is right; otherwise decline connection

“Select” – What Happens First? Is this statement in the “Library Cache”? –If statement cached then it has been recently been “parsed” and “executed” –If not cached then “parse” the statement –If cached then skip parsing stage and execute statement Select * From MyTab Order by 1;

“Select” – Parsing the Statement Does “MyTab” exist? Does user have Privs to select from “MyTab” What columns are in “MyTab” What is the first column in “MyTab” Select * From MyTab Order by 1;

“Select” – Executing the Statement Is “MyTab” data in the SGA “Buffer Cache”? –If not, fetch data into Buffer Cache Sort data in “MyTab” by the first column –If can sort records in memory then do so –If cannot sort in memory then use “Temporary” tablespace as disk-based staging area Return records to client process Select * From MyTab Order by 1;

“I/U/D” – What Happens First? Is this statement in the “Library Cache”? –If statement cached then it has been recently been “parsed” and “executed” –If not cached then “parse” the statement –If cached then skip parsing stage and execute statement Insert (a,b,c) Into MyTab;

“I/U/D” – Executing the Statement Validate values to be inserted Execute the statement –Keep DB version of the record in “Undo” tablespace until Commit or Rollback –Record changes in SGA “Redo Log Buffer” –Change records in SGA “Buffer Cache” –DBWn writes changed records to data file(s) as part of buffer cache management Insert (a,b,c) Into MyTab;

“I/U/D” – Executing the Statement If “Commit” then… –LGWn writes “Redo Log Buffer” entries to “Redo Logs” –Undo entries are invalidated If “Rollback” then… –Migrate DB version of record in Undo back to tablespace/data file Insert (a,b,c) Into MyTab; Commit; or Rollback;

Archivelog Mode Oracle Database Data Files Control Files Redo Log Files Archived Logs ARCn If Instance in “Archivelog” mode Redo Log Files are “Archived” to Archive Logs; which may be used to recover your database in the case of disaster

Creating new Database

Managing and Organizing a Database Creating a database is the first step in managing a database system A database may have been created automatically as part of Oracle9 i Server installation, or you can create a new one later Oracle Data Migration Assistant is used to migrate from an earlier version of the database

Creation Prerequisites To create a new database, you must have the following: A privileged account authenticated in one of the following ways: –By the operating system –Using a password file Sufficient memory to start the instance Sufficient disk space for the planned database To create a new database, you must have the following: A privileged account authenticated in one of the following ways: –By the operating system –Using a password file Sufficient memory to start the instance Sufficient disk space for the planned database

Planning Database File Locations Keep at least two active copies of a database control file on at least two different devices. Multiplex the redo log files and put group members on different disks. Separate data files whose data: –Will participate in disk resource contention across different physical disk resources –Have different life spans –Have different administrative characteristics Keep at least two active copies of a database control file on at least two different devices. Multiplex the redo log files and put group members on different disks. Separate data files whose data: –Will participate in disk resource contention across different physical disk resources –Have different life spans –Have different administrative characteristics

Creating a Database An Oracle database can be created using: Oracle Database Configuration Assistant The CREATE DATABASE command An Oracle database can be created using: Oracle Database Configuration Assistant The CREATE DATABASE command

Using the Database Configuration Assistant The Database Configuration Assistant allows you to: Create a database Configure database options Delete a database Manage templates –Create new template using pre-defined template settings –Create new template from an existing database –Delete database template

Create a Database

Database Information Specify: Global database name and SID The features you want to use for your database, such as: –Oracle Spatial –Oracle OLAP Services –Example Schemas Mode in which you want the database to operate –Dedicated server mode –Shared server mode

Typical or Custom Install Choose between typical or custom install

Other Parameters Archive Parameters –Use for database recovery –May also be used for a standby database Data Block Sizing –Sets the default database block size –Helps to determine the SORT_AREA_SIZE File Locations –Specify paths for trace files –Specify paths for parameter files Database storage –Specify storage parameters

Complete Database Creation Complete database creation using the following options: Create database Save as a database template Generate database creation scripts

Creating a Database Manually Decide on a unique instance and database name Choose a database character set Set the operating system variables Edit / Create the initialization parameter file Start the instance (nomount) Execute the CREATE DATABASE command Run scripts to generate the data dictionary and accomplish post creation steps Decide on a unique instance and database name Choose a database character set Set the operating system variables Edit / Create the initialization parameter file Start the instance (nomount) Execute the CREATE DATABASE command Run scripts to generate the data dictionary and accomplish post creation steps

Preparing the Parameter File Create the new initSID.ora Modify the initSID.ora by editing the parameters $ cp init.ora $ORACLE_HOME/dbs/initdb01.ora

Creating SPFILE Create the SPFILE from initSID.ora CREATE SPFILE FROM PFILE;

Starting the Instance Connect as SYSDBA Start the instance in NOMOUNT stage STARTUP NOMOUNT

@crdbdb01.sql SQL> create database db01 2 logfile 3 GROUP 1 ('/u01/oradata/db01/log_01_db01.rdo') SIZE 15M, 4 GROUP 2 ('/u01/oradata/db01/log_02_db01.rdo') SIZE 15M, 5 GROUP 3 ('/u01/oradata/db01/log_03_db01.rdo') SIZE 15M 6 datafile '/u01/oradata/db01/system_01_db01.dbf' SIZE 100M 7 undo tablespace UNDO 8 datafile '/u01/oradata/db01/undo_01_db01.dbf' SIZE 40M 9 default temporary tablespace TEMP 10 tempfile '/u01/oradata/db01/temp_01_db01.dbf' SIZE 20M 11 extent management local uniform size 128k 12 character set AL32UTF8 13 national character set AL16UTF16 14 set time_zone = 'America/New_York' 15 SQL> create database db01 2 logfile 3 GROUP 1 ('/u01/oradata/db01/log_01_db01.rdo') SIZE 15M, 4 GROUP 2 ('/u01/oradata/db01/log_02_db01.rdo') SIZE 15M, 5 GROUP 3 ('/u01/oradata/db01/log_03_db01.rdo') SIZE 15M 6 datafile '/u01/oradata/db01/system_01_db01.dbf' SIZE 100M 7 undo tablespace UNDO 8 datafile '/u01/oradata/db01/undo_01_db01.dbf' SIZE 40M 9 default temporary tablespace TEMP 10 tempfile '/u01/oradata/db01/temp_01_db01.dbf' SIZE 20M 11 extent management local uniform size 128k 12 character set AL32UTF8 13 national character set AL16UTF16 14 set time_zone = 'America/New_York' 15 ; Creating the Database

Creating a Database Using OMF Define the OMF initialization parameters in the parameter file –DB_CREATE_FILE_DEST –DB_CREATE_ONLINE_DEST_n STARTUP NOMOUNT CREATE DATABASE DEFAULT TEMPORARY TABLESPACE TEMP; STARTUP NOMOUNT CREATE DATABASE DEFAULT TEMPORARY TABLESPACE TEMP;

Troubeshooting Creation of the database fails if: There are syntax errors in the SQL script Files that should be created already exist Operating system errors such as file or directory permission or insufficient space errors occur

After Database Creation The database contains: Datafiles, control files, and redo log files User SYS with the password change_on_install User SYSTEM with the password manager Internal tables (but no data dictionary views)