Oracle Architecture

Client Computer

Application Server

Oracle Database

Lan OrInterne

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Lan OrInterne

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Client Server Environment

Application By Java or .Net Framework

Oracle Versions • E.F.T. Codd implement rules for RDBMS.• Oracle 7 ( Implements 7 Rules)• Oracle 8 (First stable version of Oracle)• 9i (integrated with java and supports all

utilities which are used By Java.)• 10G (Data Grid)• 11i called Oracle Financials Strong competitor

for SAP and ERP. • JD Adward, People Soft, SBAAN are new

competitor to SAP and ERP.

Oracle Platforms• Solaries is the 1st oracle platform provided by Sun

Micro system ( Now JAVA is oracle prod).• Oracle for Linux.• PWR Builder introduce by oracle used for data ware

housing competitor for ETL sys. By Informetica.• Cognos powerful tool as Infor. Used for data ware

housing.• ERWIN strong competitor to Oracle designer.• IDE as VB & .net called SQL developer & J Dev.• Mysql, Teradata, sybase, DB1,DB2, MS. Sql server.• 3rd Party tools as TODD by Quest Technology.

What is Data?

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Data is Defined as

• A value for an attribute of an entity.

• Entity is Real World Thing which exist and can be described in terms of one or more attributes.

• Database is Organized value of all SAME type of entity.

Memory of ORACLE( Data Dict.)• Arrangement of system table

stores data about data called as METADATA.• RDBMS discovered for non

procedural access.

Storage

LOGICAL PHYSICAL

Table Space Schema Parameter File,

Control File,Redo Log File,

Data File

Parameter File

• This is the first file oracle read at start of the database. Parameters are system variables sets environment of system, file also called as init.ora.

• From Oracle 9i SPFILE is introduce and this file is binary formatted and it is the binary version of init.ora.

Control File

• Its important file of Oracle Database and if control file is lost it means no recovery is possible also it is binary formatted.

• Oracle multiplex the file and stored in 3 files same locations name as control1.ctl, control2.ctl, control3.ctl.

3 Important Numbers

• SCN : System Change Number. It is assigned by oracle to every committed

transaction always increasing..• LSN: Log Sequence Number. The sequential number assign to redo log as they

get filled and recycled.• CPC : Check Point Counter.Its is also ever increasing number and to every

check point is assigned.

Logical Database Structure• Oracle uses logical database structure

to store data on physical operating system file.

• DATA BLOCK : Is the foundation of oracle storage. It consist of number of bytes of disk space in OS.

• EXTENT : An extents is two or more contagious oracle data blocks and a unit of space allocation.

• SAGMENT : A segment is a set of extents allocated to logical structure like table or oracle objects.

• TABLESPACE : A table space is a set of one or more data files consist of related Segments.

Schema• Schema is set of objects own by User Account.• Each schema has user account but each user

don’t need schema.• A user account is account with database having

privileges to perform predefined activities on data.

• Schema may not exist with user account but user account is exist without schema.

• Purpose : Maintenance of object like backup & recovery, implementation of security and access level.

Redo Log File• Oracle used redo base recovery and allow to recover

only committed transaction till the point of failure. • The redo base recovery in oracle is implemented

through the redo log file. • When system fails then oracle read history from

these redo log file and guaranties the recovery till the point of failure.

• These files are created at the creation of oracle db.• The files are reusable and used as round robin

passion.• Maximum size is 50Mb.

Redo Log Copies stored to 10 different geographic locations

Redo log 1 Redo log 2

Log Switch

Redo log 7

Redo log 6

Redo log 5

Redo log 4

Redo log 3

Redo log 2

Redo log 1

Redo log N..

System Global Area SGA

S

Shared SQLArea

Shared pool

area / Data

Diction.

Redo Log Buffer

Large Pool Fixed Pool

Data Buffer

Pool

3 Types of Buffer• Free Buffer : A buffer which is ready to take

new data.

• Pinned Buffer : A buffer which have data under use (not committed or not rollback.)

• Dirty Buffer : A buffer which have data which is committed called permanent.

LRU Algorithm• List Recently Used : This algorithm is used to write data from

data buffer pool (dirty buffers) in to data files.

Data Buffer Pool: Divided into 3 sections.

Keep Buffer Pool : It holds the frequently requested data.(Based on MRU).

Recycle Buffer Pool : The data which is not requested immediately after used is loaded in recycle buffer pool and eliminated after used.

Default Buffer Pool :The data which is not required in above pools is loaded in this pool.

Redo Log Buffer

• The redo log buffer is the place where data or entries are stored before writing to redo log file.

• All entries are written in serially to redo log file due to SCN.

• When user commits the data the data written to redo log file.

• If not commit or rollback then 75% full written to redo log file.

Shared Pool Area• This is the most busy area of SGA.• 3 stages of SQL.• Parsing : It resolve the reference made to the

different object in SQL statement resolution of privileges.

• Planning : After parsing the statement hand over to Optimizer for drawing execution plan to performing activities in SQL statement. Optimizer breaking down the SQL statement to get result.

• Execution : To get result and display as per request.

Parsing Types

• Hard Parse• Soft Parse

• Important Processes• Reco• Lck• Smon

Presentation End• Sangeet Kolhe Oracle DBA, System Admin (Linux)

Wainganga College Of Engineering & Management