dbms:oracle:concept:dblink

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--- dbms:oracle:concept:dblink [2010/02/24 00:26]
starlits 새로 만듦
+++ dbms:oracle:concept:dblink [2010/02/24 00:47] (현재)
starlits
@@ 줄 5: / 줄 5: @@
   - 그 제한을 알고 제대로 활용해보자.
-===== Oracle에서 remote database query 하는 중요 포인트 =====
+===== Oracle에서 remote database query 하는 중요 포인트 (1004553.6) =====
-  - Aggregate functions like MAX(), COUNT() are NOT passed across the net but rather are performed on the local node.
+  - Aggregate functions like MAX(), COUNT() are NOT passed across the net but rather are performed on the local node. \\ : **MAX(),COUNT() 같은 집계함수는 원격에서 수행되지 않고, 로컬로 데이타를 복사하여 수행됩니다.**
-  - Expressions in the SELECT list are decomposed into columns and evaluated when the data is retrieved.
+  - Expressions in the SELECT list are decomposed into columns and evaluated when the data is retrieved. \\ : **SELECT 리스트로 표현되는 것은 컬럼단위로 측정되어 되돌아 오는 것이다. **
-  - Only a relevant subset of columns are fetched across the net.
+  - Only a relevant subset of columns are fetched across the net. \\ : ** 컬럼의 서브셋만이 패치(fetch)될 수 있다.**
-  - An expression in a WHERE clause is passed across to the remote database if it compares the remote column to a literal (eg ename = 'KING').
+  - An expression in a WHERE clause is passed across to the remote database if it compares the remote column to a literal (eg ename = 'KING'). \\ : **WHERE 절에있는 표현식에서 원격의 리터럴 컬럼과 비교한다면 원격 데이터베이스를 통해서 전달한다. (예) ename='KING' **
   - Expressions in a WHERE clause are passed to the remote database if all columns are in the expression are located in the same remote table the remote database (eg emp.sal * 0.20 > emp.bonus)
   - Datatype conversion functions like TO_CHAR() in a WHERE clause are subject to the conditions in #4 and #5.
   - The optimizer only has knowledge of local indexes when making decisions about how to execute a query.
   - Remote indexes can be still be used to resolve the decomposed query sent to the remote database.
-  - GROUP BY is not sent to the remote database.
+  - GROUP BY is not sent to the remote database. \\ : **GROUP BY 는 원격디비에서 계산되지 않는다**
-  - ORDER BY is not sent to the remote database.
+  - ORDER BY is not sent to the remote database. \\ : **ORDER BY 는 원격디비에서 계산되지 않는다**

dbms/oracle/concept/dblink.1266938802.txt.gz · 마지막으로 수정됨: 2010/02/24 00:26 저자 starlits