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Oracle Apps - Techno Functional consultant

Sunday, October 30

Oracle Architecture Concepts

 To view Hostname :( DBA ) SID - System Identification                                                                  
Name
 > show user -- scott
 > connect sys as sysdba
    password: sysdba
 > show user -- sys
 > select Instance_name from gv$instance;

 To View version : select banner from v$version;
 select banner from v$version where banner like    'Oracle%';

 > desc DICT
 > select * from dict;
   --- Gives the list of System Tables in Database Server

 Oracle Architecture : Oracle Instance = Memory + Background Process
 Memory ---- 2 Types
 1. Physical memory -- Used to hold the information                 permenantly in database server .
    It is an permenant Storage Location.
    It is represented in the form of OS Files.

 2. Logical Memory -- Used to hold the information in  Temporary memory Location for manipulation purpose.
  It is represented in the form of Memory Blocks .

 Background Processes : (12 Processes ) Check Point  ( CKPT ) : It activates the Database Writer  and Log Writer whenever user issue Commit or when  there is lack of memory in server.

 Database Writer ( DBWR ): used to write the database  buffer content into data files whenever check point is  activated.

 Log Writer ( LGWR ): used to write the Redo Log buffer  content into Redo Log files whenever check point is  activated.

 Archiever ( ARCH ) : Indicates the method to be  followed while filling Redo Log files.  2 Modes
 i> Non Archieve mode :
 fills the Redo Log files in cycling process.
 ii> Archieve Mode :
 fills the files according to the DBA instructions.

 System Monitor ( SMON ): Checks for the Oracle  Instance when it is coming UP after Improper  shutdown.

 Process Monitor ( PMON ): Checks for the unsuccessful  jobs and release the resources alloted to them.

 Server Process : Executes the process in the Internal  memory of server . It uses server resources.

 Client Process : Executes the process in the Internal  memory of client. It uses client resources.

 Listner and Dispatcher Process:  Used for communication between server and client.

 Locking and Recoverer ( Lockn , Reco ) : used in the distributed server manipulations.

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