q DATABASE HAS TWO PARTS
q PHYSICAL [FILES]
v CONTROL FILES
v DATA FILES
v REDOLOG FILES
q LOGICAL [OBJECTS]
v TABLES
v VIEWS
v SYNONYMS
v TABLESPACES
v PROCEDURES
v FUNCTIONS
q DBMS/INSTANCE [MEMORY AREA]
v SGA [SYSTEM GLOBAL AREA] + BACKGROUND PROCESS
q BACKGROUND PROCESS
v FOR MAINTENANCE ACTIVITY
q DATA DICTIONARY CACHE
v META DATA [USER CREDENTIALS (AUTHENTICATION) & SCHEMA & TABLE ARE STORED]
q DATA BUFFER CACHE
v ACTUAL RECENTLY USED DATA STORE
v DATA STORED IN A BLOCK. BLOCK CAN'T BE DIVIDED
INTO PIECES
v EACH BLOCK 8K [HOW MUCH DATA CAN BE STORED IN 8K BLOCK DEPEND ON ROWSIZE
q THREE STATES OF BUFFER
v FREE BUFFER - BUFFER IS FREE TO LOAD THE
DATA
v PINNED BUFFER - YOU ARE GETTING THE DATA FROM THAT BUFFER/BLOCK
v DIRTY BUFFER - ONCE THE BLOCK MODIFIED
q TWO QUEUES IN BUFFER [HOW LONG THE DATA WILL STORE IN THE MEMORY]
v LRU [LEAST RECENTLY USED]
v MRU [MOST RECENTLY USED]
§ SELECT OPERATIONAL DATA IS THE PART OF LRU/MRU
QUEUE
v CQ [CHECK POINT QUEUE]
§ WRITE LIST WHERE MODIFIED DATA WILL STORE AND THERE IS NO SEQUENTIAL
q DATA LOAD IN THE BUFFER CACHE BY SERVER PROCESS
q DBWR [DATABASE WRITER]
v IT WRITES THE DATA FROM DATA BUFFER CACHE[CQ] TO DATA FILES
q REDO LOG BUFFER
v IT STORES CHANGE/MODIFY [DML OPERATIONAL] DATA WITH SCN [SYSTEM CHANGE NUMBER]
q LGWR [LOG WRITER]
v IT WRITES THE CHANGES DATA FROM REDO LOG BUFFER TO REDO LOG FILES
q REDO LOG FILE
v IT STORES CHANGE VACTOR WHICH WAS UPDATED
q CKPT [CHECKPOINT PROCESS]
v EVERY THREE SECONDS NOTIFY DBWR TO CHECK THE
DATA BUFFER CACHE
v IT WILL UPDATE THE LAST SCN IN EVERY DATA FILE HEADER AND CONTROL FILE
q SMON [SYSTEM MONITOR]
v THIS PROCESS IS USED FOR INSTANCE RECOVERY. IT
COPIES DATA FROM REDOLOG FILE TO DATA FILE
v COMMITTED DATA WILL BE COPIED FROM REDOLOG FILE TO DATA FILE ONLY FOR ABNORMAL SHUTDOWN
q PMON [PROCESS MONITOR]
v SERVER PROCESS WILL ALLOCATE SESSION MEMORY
AREA IN UGA [USER GLOBAL AREA]
v THIS PROCESS WILL TERMINATE USER SESSION [USER
GLOBAL AREA] WHO IS IDLE [SESSION TIME OUT] CERTAIN PERIOD OF TIME
v RELEASE/UNLOCK RESOURCES WHICH IS OCCUPIED BY THE SESSION
q REDO LOGFILE
v FOR INSTANCE, RECOVERY PURPOSES
v RECOMMEND AT LEAST 3 REDO LOG FILES
q CURRENT
v LOGWRITER CURRENTLY WRITING IN THIS GROUP
q ACTIVE
v BEFORE WRITING TO THE CURRENT LGWR HAVE BEEN WRITING IN THIS GROUP AND USED FOR INSTANCE RECOVERY PURPOSE
.
q INACTIVE
v BEFORE WRITING TO ACTIVE LGWR HAVE BEEN
WRITING IN THIS GROUP
q ARCHIVE LOG
v OLDER REDOLOG FILE
q ARCn
v ARCHIVER PROCESS