DATABASE ARCHITECTURE / SINGLE INSTANCE ARCHITECTURE

CRD FILES

C    control file

R    redo log file

D    data file

 

DB link data base link

To connect from one database server to another database server is called db link. It is one way communication

 

We have 3 types of queries

Select query     Update query    Delete query

 

All alter are called update queries

All drop are called delete queries

 

SGA                system global area

BP                   back ground process

P-mon            program monitor

S-mon            system monitor

DB writer      data base writer

LG WR            log writer

 

What is instance

SGA + BP is called instance  (instance means our database)

 

P-mon will show the data base is running or not

P-mon command      ps -ef|grep pmon

S- mon is used to up the data base server

 

Lgwr will send the updated files from redo log buffer to redo log files

Dbwr will send the data from redo log buffer to data files.

 

Dedicated server will work as bridge from client to library cache and give output

 

If out put information is not available in data dictionary cache it will collect data from data files through dirty buffer

 

Dirty buffer    if the out put information is not available in data dictionary cache then dirty buffer will send the data information from data files to data dictionary cache

 

In redo log files after filling the nodes the files will generate as archives

 

In control files it contains tables

Every table has a scn number ( system change number )

 

The checkpoint will be in header