OBIEE consistently producing very very bad SQL

Question

Hi,
We need some advice, or would like to know if people have had similar experiences. Here is our issue.
Users running reports and filtering data in presentation layer of OBIEE are seeing the OBIEE generate the SQL and sends it to the database.
This SQL which is auto generated by the OBIEE server is extremely costly. We are not whu OBIEE produces such bad sql - anyone have same problem?
When we look at explains, we see that most costly operations are when HASH operations are used. This is consistent throughout all OBIEE generated SQL.
As the SQL is of ad hock nature we do not use SPB's etc.
We are puzzled and are not sure where to start w.r.t troubleshooting.
Please help.

Answer 1

Dear guru.
Let me know what's may be wrong ?
My post is closely related to bad SQL thread.
Shortly speaking, I'd like to discuss multiple star problem.
So, Oracle Business Intelligence 11.1.1.6.0
I have three fact table A,B,C joined to common link table D ( look as dimension in Administrator )
A and B have inner join with D, while C has left outer join to D ( actually outer join defined only in BMM cause don't see how set outer join on physical layer for C ).
The matter is in generated SQL query which is broken, i.e. can't be compiled in Oracle DB.
Let me give broken piece of generated SQL.
As you can see, the subquery has reference to table T69242 in WHERE, but no such table in FROM section:
SACOMMON821644 AS
(SELECT
/*+ MATERIALIZE */
DISTINCT T68993.NAME AS c1,
T69266.DISTRICT2 AS c2,
CASE
WHEN T68993.DEPARTMENTID IN
(SELECT D1.c1 AS c1 FROM SASUBWITH820608 D1
THEN 1
ELSE 0
END AS c3,
CASE
WHEN T69266.OKATO_KOD IN
(SELECT D1.c1 AS c1
FROM SASUBWITH820633 D1
THEN 1
ELSE 0
END AS c4,
T68993.DEPARTMENTID AS c5,
T69266.OKATO_KOD AS c6,
T68993.PARENT AS c7,
T69266.PARENT_OKATO_KOD AS c8
FROM BI_MSK_DISTRICTS_STAT_HIER T69233
MOS_DISTRICTS_STAT T69266
BI_DEPARTMENTS_MFC T68993
BI_MFC_HIER T69068
DEP_OPERATORS_CNT T69220
INCIDENTS T69648
MOS_DISTRICT_POPULATION T69410
WHERE ( T69233.MEMBER_KEY = T69410.OKATO_KOD
AND T68993.DEPARTMENTID = T69068.ANCESTOR_KEY
AND T69068.MEMBER_KEY = T69220.DEPARTMENTID
AND T69220.DEPARTMENTID = T69242.DEPARTMENTID*
AND T69233.ANCESTOR_KEY = T69266.OKATO_KOD
AND T69242.OKATO_KOD* = T69410.OKATO_KOD
AND T68993.DEPARTMENTID IN
(SELECT D1.c1 AS c1 FROM SASUBWITH820658 D1
AND T69266.OKATO_KOD IN
(SELECT D1.c1 AS c1 FROM SASUBWITH820683 D1
Meanwhile in aggregation subquery of that generated SQL we have requred table
SACOMMON821667 AS
(SELECT
/*+ MATERIALIZE */
TRUNC(SUM( DISTINCT T69220.OPER_TOTAL)) AS c9,
T68993.DEPARTMENTID AS c10,
T68993.PARENT AS c11,
T69266.OKATO_KOD AS c12,
T69266.PARENT_OKATO_KOD AS c13,
SUM( DISTINCT T69410.POPUL_SIZE) AS c14,
SUM(T69648.TOTAL / NULLIF( T69242.OKATO_COUNT, 0)) AS c15
FROM BI_MSK_DISTRICTS_STAT_HIER T69233
MOS_DISTRICTS_STAT T69266
BI_DEPARTMENTS_MFC T68993
BI_MFC_HIER T69068
DEP_OPERATORS_CNT T69220
MFC_ADDRESSOKATO T69242*
LEFT OUTER JOIN INCIDENTS T69648
ON T69242.DEPARTMENTID = T69648.DEPARTMENTIDFROM,
MOS_DISTRICT_POPULATION T69410
WHERE ( T69242.OKATO_KOD = T69410.OKATO_KOD
AND T69233.ANCESTOR_KEY = T69266.OKATO_KOD
AND T69233.MEMBER_KEY = T69410.OKATO_KOD
AND T69220.DEPARTMENTID = T69242.DEPARTMENTID
AND T68993.DEPARTMENTID = T69068.ANCESTOR_KEY
AND T69068.MEMBER_KEY = T69220.DEPARTMENTID
AND T68993.DEPARTMENTID IN
(SELECT D1.c1 AS c1 FROM SASUBWITH820658 D1
AND T69266.OKATO_KOD IN
(SELECT D1.c1 AS c1 FROM SASUBWITH820683 D1
GROUP BY T68993.DEPARTMENTID,
T68993.PARENT,
T69266.OKATO_KOD,
T69266.PARENT_OKATO_KOD
And it's time to show Consistency Check results in Administrator.
There is no errors, but
WARNINGS:
Business Model Сводная таблица:
[39008] Logical dimension table A_MFC_ADDRESSOKATO has a source A_MFC_ADDRESSOKATO that does not join to any fact source.
[39020] Logical table source "Сводная таблица"."FCT Incidents"."A_Incidents": No path has been found to link all tables. There is no link between the set ( 'A_DEP_OPERATORS_CNT', 'A_MFC_ADDRESSOKATO', 'A_MOS_DISTRICT_POPULATION' ) and the set ( 'A_Incidents' ).
[39020] Logical table source "Сводная таблица"."A_DEP_OPERATORS_CNT"."A_DEP_OPERATORS_CNT ": No path has been found to link all tables. There is no link between the set ( ) and the set ( ).
[39020] Logical table source "Сводная таблица"."A_MOS_DISTRICT_POPULATION"."A_MOS_DISTRICT_POPULATION": No path has been found to link all tables. There is no link between the set ( ) and the set ( ).
I wonder, how that link can be realized, when fact tables already have joins to common dim A_MFC_ADDRESSOKATO.
Should I create Logical Dimmension for A_MFC_ADDRESSOKATO while it is actually bridge table in terms of 10G ?
Besides, as we can see from query, A B and C have its own dims.
So, finally as a result in Answers we have
ORA-00904: "T69242"."OKATO_KOD": invalid identifier at OCI call OCIStmtExecute
It should be mentioned that error is appeared only when I put measure from A_Incidents (C alias) on analys in Answers, till that all worked correctly, i.e. A,B joined successfully to D
and SQL query gave desired result.
Any suggestion on issue are greately appreciated.
Sorry for unformatted SQL, still don't know how to do it.
Sorry for the post as reply cause I don't see how create new thread.
Hope, my explanation was clear.