Retrieving information from two or more nodes - Oracle Distributed Database concepts - Distributed query

Q.  In distributed SQL statements, which of the following retrieves information from two or more nodes?
- Published on 13 Aug 15

a. Distributed query
b. Distributed update
c. Both A & B
d. None of the above

ANSWER: Distributed query


  • Nirja Shah   -Posted on 21 Sep 15
    - Distributed query - This statement retrieves information from two or more nodes.
    - For example, the following query accesses data from the local database as well as the remote sales database:

    SELECT ename, dname
    FROM scott.emp e, d
    WHERE e.deptno = d.deptno;

    - Distributed update - This statement modifies data on two or more nodes.
    - A distributed update is possible using a PL/SQL subprogram unit such as a procedure or trigger that includes two or more remote updates that access data on different nodes.
    - For example, the following PL/SQL program unit updates tables on the local database and the remote sales database:

    SET loc = 'NEW YORK'
    WHERE deptno = 10;
    UPDATE scott.emp
    SET deptno = 11
    WHERE deptno = 10;

    - The database sends statements in the program to the remote nodes, and their execution succeeds or fails as a unit.

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