oracle database training

8/3/2019 Oracle Database Training

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Oracle Database Training

4th February, 2012

Confidential | Copyright 2011 MindCraft Software Pvt. Ltd. All Rights Reserved | www.mindcraft.in


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Oracle Database Server Architecture

Oracle Instance Architecture

Oracle Database Architecture



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Oracle

Architecture



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Oracle Architecture

InstanceAn Oracle instance:

Is a means to access an Oracle database

Always opens one andonly one databaseConsists of:

Internal memory structures

Processes



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Oracle Architecture

Database buffer cache Used to holddata blocks readfrom datafiles byserver processes

Contains dirty or modified blocks and clean

or unusedor unchanged bocks Dirty and clean blocks are managedin listscalled the dirty list and the LRU

Free space is created by DBWR writingout

dirty blocks or agingout blocks from the LRU Size is managed by the parameterDB_BLOCK_BUFFERS


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Oracle Architecture

Redo LogBuffer A circular buffer that contains redo entries

Redo entries reflect changes made to the database

Redo entries take upcontiguous, sequential

space in the buffer Data storedin the redo log buffer is periodicallywritten to the online redo logfiles

Size is managed by the parameter

LOG_BUFFER Default is 4 times the maximum data block size forthe operating system


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Oracle ArchitectureShared Pool

Consists of multiple smaller memory areas Library cache

Shared SQL area Contains parsed SQL and executionplans for statements

already run against the database Procedure andpackage storage

Dictionary cache Names of all tables and views in the database Names anddatatypes ofcolumns in the database tables Privileges of all users

Managed via an LRU algorithm Size determined by the parameterSHARED_POOL_SIZE


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Oracle Architecture

Internal Memory Structures PGAProgram or process Global Area (PGA) Usedfor a single process

Not shareable with other processes

Writable only by the server process Allocated when a process is created anddeallocated when a process is terminated

Contains: Sort area Usedfor any sorts required by SQL processing

Sessioninformation Includes user privileges

Cursor state Indicates stage of SQL processing

Stack space Contains session variables


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Oracle Architecture

Background Processes - DBWR DBWR writes todisk when:

A server process cannot find a cleanreusable buffer

A timeout occurs (3 sec)

A checkpoint occurs

DBWR cannot write out dirty buffers

before they have been written to the onlineredo logfiles


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Oracle Architecture

Background Processes - LGWR Writes contents of redo log buffers toonline redo logfiles

Primary job is tokeep the redo log bufferclean

Writes out redo log buffer blockssequentially to the redo logfiles

May write multiple redo entries per writeduring high utilizationperiods

Mandatory process


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Oracle Architecture

Background Processes - LGWR LGWR writes todisk when:

A transactionis COMMITED

A timeout occurs (3 sec) The redo log buffer is 1/3 full

There is more than 1 megabyte of redoentries

BeforeDBWR writes out dirty blocks todatafiles


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Oracle Architecture

Background Processes - SMON Performs automaticinstance recovery

Reclaims space used by temporarysegments no longer in use

Merges contiguous areas offree space inthe datafiles (if PCTINCREASE > 0)

SMON wakes up regularly tocheck

whether it is neededor it may be calleddirectly

Mandatory process


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Oracle Architecture

Background Processes - CKPT Forces all modifieddata in the SGA to bewritten todatafile

Occurs whether or not the data has been

committed CKPTdoes not actually write out buffer data onlyDBWR can write to the datafiles

Updates the datafile headers This ensures all datafiles are synchronized

Helps reduce the amount of time needed toperform instance recovery

Frequency can be adjusted with parameters


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Oracle Architecture

Background Processes - ARCH Automatically copies online redo logfilestodesignated storage once they havebecome full


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Oracle ArchitectureServer Processes

Services a single user process in the dedicatedserver configurationor many user processes in theshared server configuration

Use an exclusive PGA

Include the Oracle Program Interface (OPI)

Process calls generated by the client

Return results to the client in the dedicatedserver configurationor to the dispatcher in theshared server configuration


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Oracle ArchitectureUser Processes

Runon the client machine

Are spawned when a tool or an

applicationis invoked SQL*Plus, Server Manager, OracleEnterprise Manager, Developer/2000

Custom applications

Include the User Program Interface (UPI)

Generate calls to the Oracle server


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The Physical Layer

The physical layer of the database consists of three types offiles:

One or more datafiles--Datafiles store the informationcontainedin thedatabase. You can have as few as one datafile or as many as hundreds ofdatafiles. The informationfor a single table can span many datafiles or manytables can share a set ofdatafiles. Spreading tablespaces over many datafilescan have a significant positive effect onperformance. The number ofdatafilesthat can be configuredis limited by the Oracle parameter MAXDATAFILES.

Twoor more redo logfiles--Redo logfiles holdinformation usedforrecovery in the event of a system failure. Redo logfiles, known as the redo log,store a logof all changes made to the database. This informationis usedin theevent of a system failure to reapply changes that have been made andcommitted but that might not have been made to the datafiles. The redo logfiles must perform well and be protected against hardware failures (throughsoftware or hardware fault tolerance). If redo loginformationis lost, youcannot recover the system.


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Oracle Database The Physical Layer

One or more control files--Control filescontaininformation used to start aninstance, such as the locationofdatafilesand redo logfiles; Oracle needs thisinformation to start the database instance.Control files must be protected. Oracle

provides a mechanism for storing multiplecopies ofcontrol files.


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The Logical Layer

The logical layer of the database consistsof the following elements:

One or more tablespaces. The database schema, which consists ofitems such as tables, clusters, indexes,views, storedprocedures, database triggers,sequences, and soon.


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The Logical Layer


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Segments, Extents, andData Blocks

Within Oracle, the space used to store data iscontrolled by the use of logical structures. Thesestructures consist of the following:

Data blocks--A blockis the smallest unit ofstorage in an Oracle database. The database block

contains header informationconcerning the blockitself as well as the data.

Extents--Extents consist ofdata blocks. Segments--A segment is a set of extents usedto store a particular type ofdata, as shownin


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Segments, Extents, andData Blocks


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Installation Of Oracle Database onLinux

Adddba group

Addoinstall group

Create & addoracle user tooinstall & dba

group

Set the Kernel parameters.

set the parameters in limits.conf Set .bash_profile


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Installation Of Oracle Database onLinux ( rpms required for oracle 10g)

cd /media/cdrom/RedHat/RPMS

rpm -Uvh setarch-1*

rpm -Uvh compat-libstdc++-33-3*

rpm -Uvh make-3* rpm -Uvh glibc-2*

rpm -Uvh openmotif-2*

rpm -Uvh compat-db-4*

rpm -Uvh libaio-0*

rpm -Uvh gcc-3*

rpm -Uvh compat-gcc-32-3*

rpm -Uvh compat-gcc-32-c++-3*


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Oracle Network Enviroment


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User Creation


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User Creation

Syntax:

CREATEUSER username IDENTIFIED {BYpassword | EXTERNALLY | GLOBALLY AS

'external_name'} options; options: DEFAULTTABLESPACE tablespaceTEMPORARY TABLESPACE tablespace QUOTA int{K | M} ON tablespace QUOTA UNLIMITEDONtablespace PROFILE profile_name PASSWORDEXPIRE ACCOUNT {LOCK|UNLOCK}


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Backup & Recovery

Types ofBackup

Logical Backup

ColdBackup Hot Backup

RmanBackup


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RMAN Overview

Recovery Manager (RMAN)

Recovery manager is a platform

independent utility for coordinating yourbackup and restoration procedures acrossmultiple servers


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RMAN

Create Recovery Catalog

Register Database

Full Backup

Restore & Recover The WholeDatabase

Restore & Recover A Subset OfThe Database

Incomplete Recovery

Disaster Recovery

Lists And Reports


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