如何在 obiee 的左外连接的一部分中包含分析过滤器（左连接变为内连接）

Question

Recently we had an issue of outer joins working as inner joins. The steps we did were the following: 1.Created left outer join between dim table and fact table in BMM layer. 2.Created an analysis in OBIEE to check this join 3.Sql generated shows left outer join statement but filters that were used in OBIEE analysis are placed in where clause and left outer join is ignored.

Here is the SQL code generated:

WITH SAWITH0 AS
 (select sum(T4110.SALDO_OUT_EQV) as c1,
         T5520.CAL_DAY as c2,
         T75347.LINE_CODE as c3,
         T75347.LINE_NAME as c4,
         T3160.CODE as c5
    from DM_CBM_T17_V T75347 /* D4703 Dm Cbm T17 */
    left outer join(DM_CALENDAR_V T5520 /* D03 Calendar */
   inner join(DM_FILIALS_V T3160 /* D04 Filials */Q
   inner join DM_COA_SALDO_V T4110 /* F02 Saldo Coa */
      On T3160.CODE = T4110.FILIAL_CODE) On T4110.OPER_DAY = T5520.CAL_DAY) On T4110.COA_CODE = T75347.COA_CODE
   where (T4110.OPER_DAY = TO_DATE('2021-05-06', 'YYYY-MM-DD') and
         T5520.CAL_DAY = TO_DATE('2021-05-06', 'YYYY-MM-DD'))
   group by T3160.CODE, T5520.CAL_DAY, T75347.LINE_CODE, T75347.LINE_NAME)
select D1.c1 as c1,
       D1.c2 as c2,
       D1.c3 as c3,
       D1.c4 as c4,
       D1.c5 as c5,
       D1.c6 as c6
  from (select 0     as c1,
               D1.c2 as c2,
               D1.c3 as c3,
               D1.c4 as c4,
               D1.c5 as c5,
               D1.c1 as c6
          from SAWITH0 D1
         order by c2, c5, c3, c4) D1
 where rownum <= 10000000

As you can see, the join between dim D4703 and fact F02 is created on coa_code column. Dimension D4703 has rows with null values on column coa_code. The logic we followed was that left outer join should return all rows from dim D4703 (including nulls) and only those rows from fact table that are matched. However, there sql query returns only matching rows. And when you put day filter in where clause inside on statement it is returning null values.

So I wanted to ask how to make left outer join work as intended? Is there any option in Admin tool or anywhere else?

Answer 1

We call this "preservation of the dimensions". there are two ways to achieve this with OBIEE:

1- using the full outer join, follow this article:

https://datacadamia.com/dat/obiee/obis/full_outer_join

2- the second is using a cross Join between the dimensions by adding a Fact table, follow this article:

https://datacadamia.com/dat/obiee/obis/densification_repository?s[]=preservation&s[]=dimensions

My favorite is the second approach and this is my recommendation.