Oracle Architecture
Client
Computer
Lan Or
Internet
Application
Server
Lan Or
Internet
Oracle
Database
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
Table
Space
PHYSICAL
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 N..
Redo
log 7
Redo
log 6
Redo log 1
Redo
log 5
Redo
log 4
Redo
log 3
Redo log 2
Log Switch
Redo
log 2
Redo
log 1
System Global Area SGA
Large Pool
Fixed Pool
Data
Buffer
Pool
Redo Log Buffer
Shared
pool
area /
Data
S
Diction.
Shared
SQL
Area
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
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Important Processes
Reco
Lck
Smon
Presentation End
• Sangeet Kolhe Oracle DBA, System Admin (Linux)
Wainganga College Of Engineering & Management