Distributed Query Involving a Database Opened in Read Only Mode Produces Wrong Results
(Doc ID 1517910.1)
Last updated on MARCH 07, 2019
Applies to:
Oracle Database - Enterprise Edition - Version 11.2.0.1 and laterOracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.
Symptoms
A query returns wrong results, and those results seem to be from time in the past.
Query executed involve 2 or more databases, where one database (local or remote) is open in read-only mode.
Sample of the issue when remote databases are in read-write mode and local in read-only mode:
1) Initial situation. Execute in local db:
select e.ename, v.dname from myemp e, mydept@TB2030 v where e.deptno=v.deptno;
ENAME DNAME
---------- --------------
MILLER ACCOUNTING
KING ACCOUNTING
CLARK ACCOUNTING
FORD RESEARCH
ADAMS RESEARCH
....
....
2) Update on remote table
update mydept set dname = 'AAAA' where deptno=10;
update mydept set dname = 'BBBB' where deptno=20;
update mydept set dname = 'CCCC' where deptno=30;
update mydept set dname = 'DDDD' where deptno=40;
commit;
3) In a new session in local db, still old values are returned:
select e.ename, v.dname from myemp e, mydept@TB2030 v where e.deptno=v.deptno;
ENAME DNAME
---------- --------------
MILLER ACCOUNTING
KING ACCOUNTING
CLARK ACCOUNTING
FORD RESEARCH
ADAMS RESEARCH
....
....
When expected results are (returned properly in read-write mode):
select e.ename, v.dname from myemp e, mydept@TB2030 v where e.deptno=v.deptno;
ENAME DNAME
---------- --------------
MILLER AAAA
KING AAAA
CLARK AAAA
FORD BBBB
ADAMS BBBB
....
....
Changes
One database involved in the query has been opened in read-only mode.
Cause
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In this Document
Symptoms |
Changes |
Cause |
Solution |
References |