Shrink

목적

  1. HWM (High Water Mark) 를 줄임
  2. 블록 크기 감소
  3. 블록 크기가 줄어들면서 용량 감소 및 성능 향상


실행

ALTER TABLE owner_name.table_name SHRINK SPACE;

--인덱스도 포함
ALTER TABLE owner_name.table_name SHRINK SPACE CASCADE;


작업 순서

--1. 해당 테이블, 인덱스 NOLOGGING 상태로 변경
ALTER TABLE owner_name.table_name NOLOGGING;
ALTER TABLE owner_name.index_name NOLOGGING;

--2. ROW MOVEMENT 활성화
ALTER TABLE owner_name.table_name ENABLE ROW MOVEMENT;

--3. Shrink 실행
ALTER TABLE owner_name.table_name SHRINK SPACE CASCADE;

--4. ROW MOVEMENT 비활성화
ALTER TABLE owner_name.table_name DISABLE ROW MOVEMENT;

--5. 해당 테이블, 인덱스 LOGGING 상태로 변경
ALTER TABLE owner_name.table_name LOGGING;
ALTER TABLE owner_name.index_name LOGGING;



--해당 유저 전체로 진행할 경우
SELECT 'ALTER TABLE '||owner||'.'||table_name||' NOLOGGING;' FROM all_tables  WHERE OWNER IN ('owner_name1', 'owner_name2', ... ) UNION ALL
SELECT 'ALTER INDEX '||owner||'.'||index_name||' NOLOGGING;' FROM all_indexes WHERE OWNER IN ('owner_name1', 'owner_name2', ... );

SELECT 'ALTER TABLE '||owner||'.'||table_name||' ENABLE ROW MOVEMENT;' FROM all_tables  WHERE OWNER IN ('owner_name1', 'owner_name2', ... );

SELECT 'ALTER TABLE '||owner||'.'||table_name||' SHRINK SPACE CASCADE;' FROM all_tables  WHERE OWNER IN ('owner_name1', 'owner_name2', ... );

SELECT 'ALTER TABLE '||owner||'.'||table_name||' DISABLE ROW MOVEMENT;' FROM all_tables  WHERE OWNER IN ('owner_name1', 'owner_name2', ... );

SELECT 'ALTER TABLE '||owner||'.'||table_name||' LOGGING;' FROM all_tables  WHERE OWNER IN ('owner_name1', 'owner_name2', ... ) UNION ALL
SELECT 'ALTER INDEX '||owner||'.'||index_name||' LOGGING;' FROM all_indexes WHERE OWNER IN ('owner_name1', 'owner_name2', ... );


참고