Rownum giving Incorrect Result in 11gR2 but working ok in 10gR2

Question

Hi All,
We have following query which is working fine in 10g but in 11g it is showing incorrect result.
select x.*,rownum from (select rat.rating_agency_id from bus_ca_cpty_rating rat,MST_CP_RATING mst
where rat.org_id=618
and
rat.rating_agency_id=mst.rating_agency_id
and
rat.rating_value=mst.rating_value
and
rat.heritage_system=mst.heritage_system
order by rat.rating_date,rat.rating_time)x
where rownum=1;
Result Without last Check <where rownum=1> in the query (in both 10g and 11g)
RATING_AGENCY_ID     ROWNUM
3     1
1     2
Result of the query in 11gR2 (11.2.0.3)
RATING_AGENCY_ID     ROWNUM
1     1
Result of the query in 10gR2 (10.2.0.3)
RATING_AGENCY_ID     ROWNUM
3     1
Request your help to resolve the issue(please tell me the bug name if it is a bug) and please let me know how it is processing the query in 11g.
Edited by: 906061 on Jun 19, 2012 2:22 AM

Answer 1

T.PD wrote:
906061 wrote:
Result Without last Check <where rownum=1> in the query (in both 10g and 11g)
RATING_AGENCY_ID     ROWNUM
3     1
1     2
Result of the query in 11gR2 (11.2.0.3)
RATING_AGENCY_ID     ROWNUM
1     1
Result of the query in 10gR2 (10.2.0.3)
RATING_AGENCY_ID     ROWNUM
3     1Your desired result depends on the wrong idea if implicid ordering of the results. there is no such!
Database does not sort returned rows any how (unless you use order by in your query). The order of returned rows may be consistent over a long period but if the table contents is reorganized or (as I assume) you import data to anotehr database the order may change.
To make the long storry short: you need another filter condition than <tt>rownum = 1</tt>.
bye
TPDLook closely: it looks like a standard top-n query with the order by in the sub-query.