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[Oracle Architecture][2015 04-03] Redo & Undo

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[Oracle Architecture][2015 04-03] Redo & Undo + 윤석준

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[Oracle Architecture][2015 04-03] Redo & Undo

  1. 1. WareValley http://www.WareValley.com Database Audit and Protection [ DB 접근통제 ] Database Encryption [ DB 암호화 ] Database Vulnerability Assessment [ DB 취약점 분석 ] Database SQL Query Approval [ DB 작업결재 ] Database Performance Monitoring and Management [ DB 성능관리 및 개발 ] WareValley Oracle Architecture Redo & Undo 오렌지팀 윤석준 선임연구원
  2. 2. Database security and management, WareValley. http://www.WareValley.com Redo Log  Data File과 Control File의 모든 변경 사항을 기록 -> Redo Log Online Redo 기록 (1개 Active, 나머지 Stand-by) Log Switching (기존 Active가 Full, Stand-by -> Active) Backup to Archived Redo Stand-by
  3. 3. Database security and management, WareValley. http://www.WareValley.com Use of Redo Log Database Recovery : 물리적 Media fail 발생시 Archived Redo Log를 이용하여 복구 Cache Recovery : Cache 변경사항 Disk 기록 전 Instance가 비정상 종료된 경우 Fast Commit : Disk (Random Access)는 느려서, Redo Log (Append) 에 기록 후 Commit 통보
  4. 4. Database security and management, WareValley. http://www.WareValley.com Record of Redo Log 3초마다 DBWR Process로부터 신호를 받을 때 Log Buffer의 1/3이 차거나 1MB이상 기록되었을 때 Commit or Rollback  LGWR Process가 담당 - Redo Log Buffer에 먼저 기록 한 후 특정시점에 Redo Log File에 기록
  5. 5. Database security and management, WareValley. http://www.WareValley.com Fast Commit Mechanism http://bysql.net/index.php?document_srl=22748&mid=w201201O
  6. 6. Database security and management, WareValley. http://www.WareValley.com Undo (=Rollback) Transaction Rollback : Commit 하지 않고 Rollback한 경우 Transaction Recovery : Redo Log Cache Recovery와 같이 활용 Read Consistency : Oracle의 읽기 일관성 구현 ( 다른 DBMS (DB2,SQL Server, Sybase 등)은 Lcok으로 구현 )
  7. 7. Database security and management, WareValley. http://www.WareValley.com Undo Segment http://wiki.gurubee.net/display/STUDY/Undo Transaction 별로 할당 Transaction ID [ USN# + Slot# + Wrap# ] Transaction Status Commit SCN Last UBA (User Buffer Address) Etc… Undo Header Insert : 추가된 Record의 rowid Update : 변경된 Column의 before image Delete : 지워진 Row의 before image Undo Record

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