데이터베이스 질문과 답변
시퀀스 생성 쿼리 cache질문드립니다. 뜻을 모르겠어요
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by 문진균 [2007.05.30 22:01:40]
CREATE SEQUENCE SEQ_MSNMSG
INCREMENT BY 1 START WITH 1 => 1부터 시작하고 1씩 증가하라.
MAXVALUE 99999999 =>99999999가 되었을 때 1로 돌아가라.
MINVALUE 1 => 최소값은 1이다.
NOCYCLE CACHE 20 NOORDER ; => 이부분이 무슨 의미인지 알고 싶습니다.
cache의미 부탁드려요..
제가 위에 설명써놓은 것은 다 맞나요?
by finecomp
[2007.05.31 00:00:00]
오역의 위험(?)때문에 오라클 다큐먼트를 그대로 올리니 읽어보시길...^^;
NOCYCLE Specify NOCYCLE to indicate that the sequence cannot generate more values after reaching its maximum or minimum value. This is the default.
CACHE Specify how many values of the sequence the database preallocates and keeps in memory for faster access. This integer value can have 28 or fewer digits. The minimum value for this parameter is 2. For sequences that cycle, this value must be less than the number of values in the cycle. You cannot cache more values than will fit in a given cycle of sequence numbers. Therefore, the maximum value allowed for CACHE must be less than the value determined by the following formula:
(CEIL (MAXVALUE - MINVALUE)) / ABS (INCREMENT)
If a system failure occurs, all cached sequence values that have not been used in committed DML statements are lost. The potential number of lost values is equal to the value of the CACHE parameter.
Note:
Oracle recommends using the CACHE setting to enhance performance if you are using sequences in a Real Application Clusters environment.
NOORDER Specify NOORDER if you do not want to guarantee sequence numbers are generated in order of request. This is the default.
건승하시길...수고하세요~~
NOCYCLE Specify NOCYCLE to indicate that the sequence cannot generate more values after reaching its maximum or minimum value. This is the default.
CACHE Specify how many values of the sequence the database preallocates and keeps in memory for faster access. This integer value can have 28 or fewer digits. The minimum value for this parameter is 2. For sequences that cycle, this value must be less than the number of values in the cycle. You cannot cache more values than will fit in a given cycle of sequence numbers. Therefore, the maximum value allowed for CACHE must be less than the value determined by the following formula:
(CEIL (MAXVALUE - MINVALUE)) / ABS (INCREMENT)
If a system failure occurs, all cached sequence values that have not been used in committed DML statements are lost. The potential number of lost values is equal to the value of the CACHE parameter.
Note:
Oracle recommends using the CACHE setting to enhance performance if you are using sequences in a Real Application Clusters environment.
NOORDER Specify NOORDER if you do not want to guarantee sequence numbers are generated in order of request. This is the default.
건승하시길...수고하세요~~
by 정순표
[2007.05.31 00:00:00]
chche 는 스쿼시를 숫자만큼 저장했다가
불러오면서 숫자를 카운트 해주는 역활을 합니다.
저장공간에 20개 저장했다가 주루룩 불러올때 빠르게 하기 위한 역할도 하죠..
불러오면서 숫자를 카운트 해주는 역활을 합니다.
저장공간에 20개 저장했다가 주루룩 불러올때 빠르게 하기 위한 역할도 하죠..
) 버튼을 클릭하여 작성 하시면 됩니다.