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Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
Oracle archi ppt
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Oracle archi ppt

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  • 1. 인사말
    2. 강사소개
    3. 강의 목적
  • 1. Architecture의 중요성
    2. Oracle8(TM) Server와 Oracle8(TM) Server Enterprise Edition 의 차이
    - Oracle8(TM) Server : Oracle Workgroup Server의 대체명.
    - Oracle8(TM) Server Enterprise Edition : Oracle7 Server의 대체명.
    전사급의 OLTP나 DW와 같은 애플리케이션을 위해
    강력한 인상을 줄 수 있도록 ”Enterprise”를 명칭에 삽입..
  • 1. Architecture의 중요성
    2. Oracle8(TM) Server와 Oracle8(TM) Server Enterprise Edition 의 차이
    - Oracle8(TM) Server : Oracle Workgroup Server의 대체명.
    - Oracle8(TM) Server Enterprise Edition : Oracle7 Server의 대체명.
    전사급의 OLTP나 DW와 같은 애플리케이션을 위해
    강력한 인상을 줄 수 있도록 ”Enterprise”를 명칭에 삽입..
  • 1. 오라클이란?
    2. 오라클의 Overview
    3. SGA란, SGA의 구성요소 3가지와 SGA의 역할
    4. Background Process에 대해 (역할과 어떤것이 있는지)
    5. Instance = SGA + Background Process
    6. Server Process/User Process
    7. File 의 구성요소와 간단한 역할
    1) Fixed size
    이 부분은 백그라운드 프로세스가 access하는데 필요한 일반적인 정보를 포함하고 있는 부분으로서 user data는 없으며 parameter로 크게 또는 작게 지정 할 수 없다.따라서 항시 instance내에서 일정한 크기를 갖으며 버젼별,os 별로 약간의 차이는 있다.
    2) Variable size
    이 size는 parameter file(initSID.ora)의 SHARED_POOL_SIZE에서 지정한 크기와 각종 파라미터로 지정한 값의 합으로 결정된다. SHARED_POOL_SIZE는 byte단위로 지정하며 OS의 shared memory
    segment보다는 작아야 한다. InitSID.ora file에는 instance와 관련된 여러 parameter가 지정되어
    있는데 이곳의 parameter의 지정 값에 따라서 SGA의 영역에 일정한 부분을 차지한다.따라서 SGA의 크기에 영향을 주는 요소는 단순히 SHARED_POOL_SIZE이외에 각종 parameter에 의해 점유되는 부분을 고려해야 한다.일반적으로 각 parameter값을 크게 할 수록 메모리 사용은 일정한 비율로 늘어나며 다음은 몇가지 예이다.
    *DB_FILES - 10 증가시 약 6K소모
    *DML_LOCKS - 100 증가시 9.7K소모
    *PROCESSES - 10 증가시 19.5K 소모
    *SEQUENCE_CACHE_ENTRIES - 10 증가시 약 1.17K 증가
    *ROW_CACHE_ENQUEUES - 100 증가시 약 3.5K 증가
    *SESSIONS - 10 증가시 약 5.3K 증가 : :
    현재 각 parameter에 의해 점유된 SGA내의 점유된 메모리 영역의 크기는 V$SGASTAT에서 조회하여 볼 수 있다.(select * from v$sgastat;)
  • 3) Database Buffer Cache
    SGA에서 disk의 data가 저장되는 곳으로서 performance에 큰 영향을 준다.
    이곳의 size가 작으므로 발생 할 수 있는 현상은 빈번한 disk i/o이다.크기는 DB_BLOCK_BUFFERS로 지정하며 buffer의 갯수를 지정한다.byte 산정은 DB_BLOCK_BUFFERS * DB_BLOCK_SIZE로 산출된다.
    4) Log Buffers
    이것은 redo log 용도로 사용될 메모리 내의 log buffer size를 말 한다.크기는 byte단위로 LOG_BUFFERS 로 지정한다.
    1. SGA 의 특징
    - data와 control information을 저장한다.
    - SGA는 non-paged, non-swapped memory
    - 전체 메모리에 1/3 정도로 구성한다.
    2. 오라클 기본 메모리 구조
    - software code areas : 실행되고 있거나 실행될 오라클을 위한 코드가 저장되는 곳
    - the system global area (SGA)
    the database buffer cache, the redo log buffer, the shared pool
    - program global areas (PGA) : 프로세스(Server,background)에 대한 data와 control
    정보를 담고있다.( stack areas, data areas )
    - sort areas (SORT_AREA_SIZE에서 지정)
    3. Shared Pool 의 구성과 역할
    - Identical SQL문 (by Hashing algorithm)
  • 1. Dirty List : 변경은 되었으나 아직 디스크에는 반영안된 dirty buffer를 가지고 있음
    2. LRU List : 다음 3가지로 구성되어 있다.
    - Free Buffer : 사용가능
    - Pinned Buffer : 현재 사용중
    - Dirty Buffer : update로 locking 되어진 상태(Dirty List로 옮겨지지 않은 버퍼)
     Dirty Buffer => Dirty List로 간다.
    * LRU end MRU end
    <--------------------------------------------------------------------->
    ---->
    free buffer를 찾는다.
    사용하면 MRU end 로 보낸다
    dirty buffer를 만나면 dirty list로 보낸다.
  • - Can be by bypassed using the UNRECOVERABLE keyword in the CREATE TABLE, CREATE INDEX statement
    - Can be bypassed by the Oracle data loader
    - Recovery를 위해
    - Update, Delete, Insert 순으로 저장크기
    - If an instance failure occurs, the redo log files are used to recover the modified data that was in memory.
    - These files are only used for recovery
  • 1. Background Process의 종류
    - PMON, SMON, DBWR, LGWR : mandatory processes
    - 위 4개중 어느 하나가 죽어도 instance는 죽는다 : Instance Restart
    - the other processes are optional
    2. Server Process/User Process
    3. Legend
    - LCKn : Lock process (parallel server system에서 Instance간의 locking담당)
    - RECO : Recoverer process (분산 트랜잭션에 대한 failure 해결)
    - PMON : Process monitor
    - SMON : System monitor
    - CKPT : Checkpoint
    - ARCH : Archiver
    - DBWR : Database writer
    - LGWR : Log writer
    - Pnnn : Parallel processes
    - SNPn : Snapshot process (Replication)
     Background Process 참조(P51)
  • 1. Properties LGWR
    - 1개의 인스턴스에는 1개의 LGWR이 있다
    - Transaction이 redo log file에 기록된 후에 Commit이 마무리된다.
    (왜? 인스턴스 failure대비)
    - 한 User가 Commit을 한후 LGWR flush를 하기전 다른 유저가 commit을 할 경우
    commit당 I/O의 비율을 줄이기 위해 piggyback된다. (계속수행하고 에러발생시
    재처리한다)
    - Long Transaction일경우 1/3이 차면 redo log buffer 를 비운다.
    2. Log Switch
    - log switch : LGWR은 현재 redo log group => 다음 redo log write
    - log switch시에는 check point가 자동으로 수행된다
    - Redo log가 다 찾을경우, DBA가 직접 “ALTER SYSTEM SWITCH LOGFILE”
    - 1개의 멤버라도 괜챤으면 계속수행된다.
    3. Log Sequence #
  • * PMON의 역할중 clean-up
    alter system kill session ‘ , ‘
    => serial# 증가하는 경우
  • 0. When Do Checkpoint
    - every log switch
    - LOG_CHECKPOINT_TIMEOUT
    - LOG_CHECKPOINT_INTERVAL
    - instance shutdown (not abort)
    - ALTER SYSTEM CHECKPOINT (by DBA)
    - tablespace offline while at least one of its files is online
    1. RECO : 분산 트랜잭션에 대한 Failure시 해결한다
    2. LCKn : Parallel Server system에서 인스턴스간의 locking을 담당한다.
    3. Pnnn ( Parallel Query process) : parallel query, parallel index creation, parallel data loading, parallel CREATE TABLE AS SELECT
    4. SNPn (Snapshot process) : Automatic refreshes of snapshot (read-only replicated tables), the server job queues and replication queues
    5. QMNn (Queue Monitor) : message queue를 모니터 하는 Oracle Advanced Queuing을 위한 프로세스
    <Options>
    1. The parallel query option 별도라이센스
    2. The procedural option is required for snapshots. It is included with the Oracle7 licensed product.
    3. The distributed option is required for distributed transactions. 별도 라이센스
    4. The replication option 별도 라이센스
  • 1. Single Task, Two-Task
    - Single-Task : User(Application Code)와 Server(Oracle Server Code)가 하나의’
    Process Batch성 작업에서 30%정도의 향상효과가 있다.
    Re-make해 주어야한다.
  • 1. 각 파일의 기능과 역할
    - Datafile : Database의 모든 data를 저장하는 곳이다. Table, Index와 같은 Logical
    구조를 물리적으로 저장하는 곳이다.
    - Redo Log Files : Recovery를 위해존재한다. 데이타베이스를 변경하는 모든 변화를
    record 단위로 기록한다.
    적어도 2개의 redo log group 이 있어야하며, 그룹당 2개이상의 멤버
    각 그룹의 멤버는 같은 Size와 같은 내용을 갖는다.
    모든 그룹의 멤버의 개수는 갖다.
    - Control File : 데이타베이스의 물리적인 구조와 데이타베이스 Status등을 저장한다.
    Database file, log file, database name, Synchronization information
    서로 다른 disk에 적어도 2개 이상을 갖도록 한다.
    - Parameter File : 뒤 참조
    - Alert File : chronological log of message and errors
    internal error (ORA-600), block corruption error(ORA-1578), dead lock
    errors(ORA-60), DDL, Server Manager statement(startup, shutdown..)
    BACKGROUND_DUMP_DEST
    - Trace File : 에러발생시 BACKGROUND_DUMP_DEST, USER_DUMP_DEST
    2. Control file은 다음과 같은 경우에 다시 생성한다.
    . CONTROL FILE이 손상되었는데, 이용 가능한 BACKUP FILE이 없을 경우
    . 데이타베이스 이름을 변경할 경우
    . DATA FILE, LOG FILE의 MAX 갯수를 확장할 때
     alter database backup controlfile to trace noresetlogs;
  • 1. Physical storage structure
    - Datafile : a physical datafile belonging to a single tablespace
    - Segment : a set of one or more extents that contains all the data for a specific
    structure within a tablespace
    - Extents : a set of contiguous data blocks in a database
    - Block : multiple physical file blocks allocated from an existing datafile
    2. Logical storage structure
    - Tablespace : a logical repository for physically grouped data
    - Table / Clusters / Indexes
  • < Tablespace >
    1. 각 tablespace는 여러 개의 OS 파일을 가질수 있다.
    2. Tablespace는 database가 돌고있는 중에 online할수 있다.
    3. SYSTEM, RBS을 제외한 tablespace는 offline 할 수 있다.
    4. Read-write <=> Read-only 변환 가능
    5. 해당 tablespace에 생성된 오브젝트는 다른 테이블스페이스에 할당되지 않는다.
    <Tablespace Uses>
    1. Controlling space allocation and assign space quotas to users
    2. 각 tablespace를 online, offline하여 관리
    3. Data storage를 분산하면 I/O 경합이 줄어 효율이 향상될 것이다.
    4. 부분 backup과 부분 recovery가 가능하다.
    5. Static data에 대해 read-only tablespace로 할 수 있다.
    < SYSTEM tablespace>
    1. Database operation을 위해 필요함
    2. Data dictionary 정보, stored procedures/package/trigger 의 definition
    3. SYSTEM rollback segment
    4. Can contain user data
  • < Non-system Tablespace >
    1. Database 관리상 편하다
    2. Rollback segment, temporary segment, application data/index, user space
    3. Rollback segment tablespace
    4. Temporary Tablespace : 영구적인 data, index는 저장안함, dba가관리
    ( V$SORT_SEGMENT )
    5. Resizing datafile (AUTOEXTEND option)
    6. Read-only tablespace : online, no active tx, no active rbs, not online backup
  • 1. Block의 구조 자세히
    - Header : general block information
    - Table directory : information about the table
    - Row directory : row information about the actural rows in the block (1row당 2bytes)
    - Free space : for insert or updates of rows, or for additional transaction entries
    - Row data : stores table or index data
    2. Space Management Parameters
    - PCTFREE : udpate를 위해 비워두는 공간 (default 10)
    - PCTUSED : pctused 밑으로 내려가면 freelist에 등록되어 새로운 row insert(40)
    - INITRANS : block header에 처음 할당되는 tx entries의 개수
    (각 tx entry는 23bytes) - MAXTRANS : block에 동시에 access할 수 있는 tx 의 개수 (255개까지)
    block 의 free space 를 사용한다. 즉, tx이 많을 경우 pctfree를 늘린다
    3. Chaning and Migration
    - Analyze table table_name list chained rows;
    - utlchain.sql (create chained_rows)
  • 1. PCTFREE ={ (max# bytes per rows) - (#bytes inserted per rows) } / (max# of bytes per row) * 100
    2. default : pctree 10, pctused 40
    3. pctfree + pctused < 100 (90% recommanded)
    4. Example
    (1) Setting a Lower PCTFREE
    - block 사용율을 높인다(사용될 블럭의 수를 줄인다)
    - block reorg로 인해 process cost가 는다
    - row migration 가능성이 높다
    (2) Setting a Higer PCTFREE
    - update를 위해 여유공간을 많이 둔다 (사용될 블럭의 수가 많이든다)
    - block reorg가 필요없어서 process cost가 적다
    - chain row를 줄일수 있다
    (3) Setting a Lower PCTUSED
    - block이 free될 가능성이 작아 process cost를 줄인다
    - unused space가 많아 진다
    (4) Setting a Higher PCTUSED
    - block이 free될 가능성이 높아 process cost가 는다
    - space usage가 높아진다
  • 1. Storage Parameter
    - INITIAL : 5 blocksNEXT : 5blocksMAXEXTENTS
    - MINEXTENTSPCTINCREEASEOPTIMAL
    - FREELISTSFREELIST GROUPS(OPS)
    2. Storage Parameter가 쓰이는 곳
    - table, clusters, indexes, rollback segments, tablespaces(default setting only)
    3. Object level > tablspace level > system level
    4. initial -> next -> next*(1+pctincrease/100)
  • 1. 각각의 Segment 역할
  • Transcript

    • 1. Overview of Oracle Database
    • 2. Part 1. Introduction to Database System  Introduction to Database  History of RDBMS  Entity-Relationship Modeling  Database Language
    • 3. Introduction to Database  File-Based Approach  Each program defines and manages its own data  Limitation   Duplication of data  Data dependence  Incompatibility of files   Separation and isolation of data Fixed queries/proliferation of application program Database Approach  A shared collection of logically related data, designed to meet the information needs of an organization
    • 4.  Database Management System(DBMS)  A software system that enables users to define, create and maintain the database and provides controlled access to database  DDL  DML : procedural, non-procedural  Control : security, integrity, concurrency control, recovery control, user-accessible catalog  Components of the DBMS Environment  Hardware - Software - Data - Procedures - People
    • 5.  Advantages of DBMS - Control of data redundancy - Economy of scale - Data consistency - Balance of conflicting requirements - More information from the same amount of data - Sharing of data - Improved data accessibility and responsiveness - Improved data integrity - Increased productivity - Improved security - Improved maintenance through data independence - Enforcement of standards - Increased concurrency - Improved backup and recovery services  Disadvantages of DBMS - Complexity, Size, Cost of DBMSs, Additional H/W costs - Cost of conversion, Performance, Higher impact of a failure
    • 6.  Three-Level Database Architecture  External Level The users’ view of the database  Conceptual Level The community view of the database  Internal Level The physical representation of the database on the computer
    • 7.  Functions of a DBMS 1. Data storage, retrieval, and update 2. A user-accessible catalog 3. Transaction support 4. Concurrency control services 5. Recovery services 6. Authorization services 7. Support for data communication 8. Integrity services 9. Services to promote data independence 10. Utility services
    • 8.  Components of a DBMS Programmers Users DBA Application Programs Queries Database Schema DML preprocessor Query processor DDL compiler Program object code Database manager Dictionary manager Access methods File manager System buffers Database and system catalog DBMS
    • 9.  Components of Database Manager Authorization control Integrity checker Command processor Query optimizer Transaction manager Scheduler Buffer manager Recovery manager Data Manager
    • 10. History of RDBMS  History of DBMS  1960s - Apollo moon-landing project, GUAM  mid 1960s - IMS by IBM (hierarchical DBMS)  mid 1960s - IDS by GE (network DBMS)  1965 - CODASYL(Conference on Data SYStems Language)  1967 -DBTG(Data Base Task Group)  1970 - E.F.Codd of the IBM Research Lab.  Late 1970s - System R project at IBM  1980s - commercial relational DBMS(DB2, Oracle, Informix..)  Now - OODBMS, ORDBMS
    • 11.  Terminology  Relation : a relation is a table with columns and rows  Attribute : an attribute is a named column of a relation  Domain : a domain is the set of allowable values for one or more attributes  Tuple : a tuple is a row of a relation  Degree : the degree of a relation is the number of attributes it contrains  Cardinality : the cardinality of a relation is the number of tuples it contains  Relational database : a collection of normalized relation
    • 12.  Properties of Relations  The relation has a name that is distinct from all other relation names  Each cell of the relation contains exactly on atomic value  Each attribute has a distinct name  The values of an attribute are all from the same domain  The order of attributes has no significance  Each tuple is distinct; there are no duplicate tuples  The order of tuples has no significance, theoretically
    • 13.  When is a DBMS Relational?  Foundational rules Rule 0 : Foundational rule Rule 12 : Nonsubversion rule  Structural rules Rule 1 : Information representation Rule 6 : View updateing  Integrity rules Rule 3 : Systematic treatment of null values Rule 10 : Integrity independance  Data manipulation rules Rule2 : Guaranteed access Rule 4 : Dynamic online catalog based on the relational model Rule5 : Comprehensive data sublanguage Rule7 : High-level insert, update, delete  Data independence rules Rule8 : Physical data independence Rule11 : Distribution independence Rule 9 : Logical data independence
    • 14. Entity-Relationship Modeling  Concepts of the E-R Modeling  Entity Types An object or concept that is identified by the enterprise as having an independent existence  Attributes A property of an entity or a relationship type  Relationship Types A meaningful association among entity types
    • 15.  Conceptual Database Design  The process of constructing a model of the information used in an enterprise, independent of all physical considerations  Logical Database Design  The process of constructing a model of the information used in an enterprise based on a specific data model, but independent of a particular DBMS and other physical considerations.  Physical Database Design  The process of producing a description of the implementation of the database on secondary storage; it describes the storage structures and access methods used to archieve efficient access to the data
    • 16. Database Language  SQL  1974 - SEQUEL by D.Chamberlin (IBM)  1975 - SQUARE by Boyce (System R project)  1976 - SEQUEL/2 (SQL) by Chamberlin and Boyce)  late 1970 - SQL(Oracle), QUEL(Ingres)  1982 - Relational Database Language(RDL) : ANSI  1987 - ISO standard  1989 - Integrity Enhancement Feature (ISO)  1992 - SQL2(SQL92) : ISO
    • 17.  DML  SELECT  INSERT  UPDATE  DELETE  DDL  CREATE(DROP) SCHEMA  CREATE(ALTER, DROP) DOMAIN  CREATE(ALTER, DROP) TABLE  CREATE(DROP) VIEW  CREATE(DROP) INDEX
    • 18.  Advanced SQL  View  Integrity Enhancement Feature  Primary key  Unique  Foreign key  Access Control  Embedded SQL  Host Language Variables  Application Programming Interface  Dynamic SQL
    • 19. Part 2. Understanding Oracle Database  Overview of oracle Database Architecture  Memory Structure  Process Structure  Storage Structure  New Features
    • 20. Overview of Oracle Architecture PMON SMON RECO D000 S000 Redo Log Buffer SGA Shared SQL Area P000 Database Buffer Cashe * Total SGA Size : 1700 Mbyte * Fixed Size : 70 Kbyte * Variavle Size : 490 MByte TL-812 4,000,000 KByte Server 1,200,000 KByte DBW0 CKPT Data File Raw Device USER 2,100 KByte LGWR ARCH Archive Log Mode(50M)
    • 21. Memory Structure : Shared Pool Shared Pool Library Cache Dictionary Cache Shared SQL Area Control Structures for example: PL/SQL Procedures and Package Control Structures for examples; Locks Library Cache handles and so on ... Character Set Conversion Memory Network Security Attributes and so on .. Reusable Runtime Memory  Shared Pool Contents - Text of the SQL or PL/SQL statement - Parsed form of the SQL or PL/SQL statement - Execution plan for the SQL or PL/SQL statements - Data dictionary cache containing rows of data dictionary information  Library Cache - shared SQL area - private SQL area - PL/SQL procedures and package - control structures : lock and library cache handles  Dictionary Cache - names of all tables and views in the database - names and datatypes of columns in database tables - privileges of all Oracle users  SHARED_POOL_SIZE
    • 22. Memory Structure :Database Buffer Cache  Database Buffer Cache holds copies of data blocks read from disk  All users concurrently connected to the system share access to the buffer cache  Dirty List  LRU List  Size = DB_BLOCK_SIZE * DB_BLOCK_BUFFERS SGA Shared Pool Shared SQL Area Database Buffer Cache
    • 23. Memory Structure :Redo Log Buffer  Circular buffer containing information about changes made to the database  save it redo entry  Redo Entries is used when Database Recovery  DBWR write contents of Redo Log Buffer to Online Redo Log  LOG_BUFFER change vector #1 redo record change vector #1 change vector #1
    • 24. Oracle Processes SNPn SMON PMON Pnnn RECO SGA Database Buffer Cache Snnn Redo Log Buffer Offline Storage Device Dedicated Server Process DBWR Dnnn LCK0 User Process LGWR ARCH CKPT Control Files Users Data Files Redo Log Files
    • 25. Background Process  DBWR (Database Writer) - write all dirty buffers to datafiles - Use a LRU algorithm to keep most recently used blocks in memory - Defers write for I/O optimization  dirty list reaches a threshold length  A process SCNAS a specifed number of buffer in the LRU without finding free buffer  A time-out occurs  DBWR checkpoint occurs  LGWR (Log Writer) - writes redo log entries to disk  Commit occurs  The redo log buffers pool becomes one-third full  DBWR completes cleaning the buffer blocks at a checkpoint  LGWR time-out - A commit confirmation is not issued until the tx has been recorded in the redo log file
    • 26. Cont’d  PMON (Process Monitor) - Cleans up abnormally terminated connection - Rolls back uncommited transactions - Releases locks held by a terminated process - Frees SGA resources allocated to the failed processes - Database maintenance  SMON (System Monitor) - Performs automatic instance recovery - Reclaims space used by temporary segments no longer in use - Merges contiguous area of free space in the datafile
    • 27. Cont’d  CKPT (Check Point) - is enabled by setting the parameter CHECKPOINT_PROCESS=TRUE - If enabled, take over LGWR’s task of updating files at a checkpoint - Updates header of datafiles and control files at the end of checkpoint - More frequent checkpoint reduce recovery time from instance failure - CKPT improve the performance of database with many database files  ARCH (Archiver) - Copies redo log files to tape or disk for media failure - Operates only when a log switch occurs - Is optional and is only needed when in ARCHIVELOG mode - May write to a tape drive or to a disk  LCKn (Lock), Dnnn (Dispatcher), Snnn (Server), RECO (Recover), Pnnn(Parallel), SNPn(Snapshot process)(Job Queue), QMNn(Queue Monitor),
    • 28. Server/User Process  User Processes - A user process is used when a user runs an application program - Runs the tool/application and is considered the client - Passes SQL to the server process and receives the results  Server Processes - A server process must place the data in the database buffer cache - Parce and execute SQL statements - Read data blocks from disk into the shred database buffers of the SGA - Return the results of SQL statements to the user process  Parse : check syntax, security access, object resolution, optimization  Execute : applies the parse tree to the data, perform a physical read and change  Fetch : Passes data to the user (only SELECT)
    • 29. Oracle Files  Datafile  Redo Log Files  Control Files  Parameter File  Archive File  Log File (alert*.log, sqlnet.log, listener.log...)  Trace File
    • 30. Storage Architecture  Physical storage structures  Data files  Segments  Extents  Blocks  Logical storage structures  Tablespaces  Tables / Clusters / Indexes  Rows  Columns
    • 31. Physical Storage Architecture  Relationship among Segments, Extents, and Blocks Segment 96K Extent Extent 24K 72K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K Database Blocks 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K 2K
    • 32. Logical Storage Architecture  Relationship between tablespaces and datafiles Database System Tablespace DATA1.ORA DATA2.ORA USER Tablespace DATA3.ORA
    • 33. Cont’d  Objects stored in tablespaces Tablespace (one or more datafiles) Table Table INDEX INDEX INDEX INDEX INDEX INDEX INDEX INDEX INDEX INDEX Table Database Files Objects (Physical structures associated with only one tablespace) (stored in tablespace may span serveral datafiles)
    • 34. Block Header Table Dictionary Row Dictionary Free Space General Block Information (Block add, Segment type) 85 ~ 100 bytes Table info in Cluster Row info in Block (2 byte per row) Row Data using when New Row Insert or Update (pctfree, pctused) Table or Index Data
    • 35. PCTFREE / PCTUSED PCTFREE PCTFREE PCTUSED PCTUSED 20% Free space 61% Free space PCTUSED = 40 PCTFREE = 20   Insert new row until 80% 20% use when Update   Can insert new row when below 60% When Usage is below 40% (61% Free space), block is listed in FREELIST
    • 36. Extent A set of contiguous database blocks within a datafile. Extent are allocated when. - The segment is created (INITIAL EXTENT) - The segments grows (NEXT EXTENT) - The table is altered to allocate extents. Extent are de-allocated when the - The segment is dropped and truncated. - The segment is larger than optimal and contains free extents (for rollback segments only) Each segment is created with at least on extend( initial extent ) ( Rollback segment : 2) ALTER TABLE table_name DEALLOCATE UNUSED
    • 37. Segment a set of one or more extents that contains all the data for a specific type of logical storage structure within a tablespace  Data Segment - A collection of extents that holds all of the data for a table or a cluster  Index Segment - A collection of extents that holds all of the index data for search optimization on large tables and clusters  Rollback Segment - A collection of extents that holds rollback data for rollback, read-consistency, or recovery  Temporary segment - A collection of extents that holds data belonging to temporary tables created during a sort operation  Bootstrap segment - An extent that contains dictionary definitions for dictionary tables to be loaded when the database is opened. 
    • 38. Oracle Client/Server Architecture NETWORK Server b Client Application Server/Server Client/Server Server A  Benefit of Client/Server Component - Database S/W work on Server - Minimize network resource - concurrency, consistency, transparency - Only Server upgrade to increase size - Minimize Client H/W spec - concurrency, consistency, transparency

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