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2777473 - MDX: FAQ for Power BI accessing BW or BW/4HANA

Symptom

Q1: How can issues with Power BI and BW Queries be analyzed?

Power BI uses the MDX interface and general MDX troubleshooting steps can be followed.

    1. Check if the frontend vendor can provide the MDX statement. Go with it to transaction MDXTEST and test the issue there.
    2. If this is not possible you can analyse what the frontend is requesting from the BW backend by analysing the RSTT trace (see SAP Note 899572 on details of this trace).
    3. From the RSTT trace the MDX statements can be extracted and viewed in transaction MDXTEST (See SAP Community Wiki: Extracting MDX Statements from RSTT Trace).
    4. The query used in the MDX statement can be checked in transaction RSRT.

Check the SAP Community Wiki on the MDX interface for details.

The generation of the MDX statement is done by Power BI. If you identify any problems with the syntax or the semantics of the statement contact Power BI support.

Q2: Extract from BW in Power BI runs into memory problems. What to do?

Review general SAP Note: 1381821 Memory and Performance Analysis for MDX

When receiving memory errors when running the reports, these are in 99% of cases due to the size of the requested resultset.

Generally, the MDX interface is not meant to be used for mass data extraction (also see SAP Note 1968598).

There are now two options:

  1. Increase the memory configuration in your system with your basis team (check the parameters in transaction ST22)
  2. Decrease the size of the requested result set. The main problem in the generated MDX statements are:
    1. Missing filters.
    2. Number of dimensions requested.
    3. High number of dimension properties.
    4. The NON EMPTY statement is NOT used in the MDX generated by Power BI (see MDX: Empty and NON Empty).

Q3: Performance issues in Power BI Extracts. What to do?

See Q2.

Q4: Why are zero records in Power BI unexpectedly displayed?

The BW Query property Zero suppression is ignored the MDX processor. Instead the statement NON EMPTY decides if NULL records are displayed.

See for more details the SAP Community: MDX: Empty and NON Empty.

Q5: Why do results in Power BI differ to results from RSRT or BEx?

  1. For BW Queries with customer exit variables:
       Test the behaviour with and wihout the RSADMIN parameter MDX_GET_MEMBERS_NO_UEXIT_VARS.
       The RSADMIN  parameter can be set with the report SAP_RSADMIN_MAINTAIN (the parameter is documented in SAP Note 2378998). 
  2. Review the MDX restrictions:
        See SAP Note: 820925 MDX - Restrictions

Q6: Why is Power BI not able to connect to CDS views?

Implement the following SAP Note: 2647905 - BAPI GetHierarchies: Error message RSSH_GET_HIERARCHIES_OF_IOBJNM-1

Q7: Power BI problems after upgrade due to changing UIDs:  'The key didn't match any rows in the table'.

  1. Check if the following SAP Note can help to overcome this error:
        2658221 - BAPI GetMeasures: Changes resulting from SAP Note 2569461
  2. After applying the SAP Note you will also need to set the RSADMIN parameter as described in the same.
  3. Also regenerate the BW query in transaction RSRT (Generate Report).

Q8: When connecting to a BW query from Power BI,  the following error occurs: Hierarchy does not exist...

BW Hierarchies are buffered for performance reason, sometimes inconsistencies may occur. Please, follow KBAs:
     2433852 - How to repair inconsistent Hierarchies.
     2493403 - HIER: System error in program CL_RRHI_INCL_CREATOR_TID and form _FIND_DOUBLICATES-1-


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Environment

  • SAP BW/4HANA 1.0
  • SAP BW/4HANA 2.0
  • SAP NetWeaver 2004
  • SAP NetWeaver 7.0
  • SAP NetWeaver 7.3
  • SAP NetWeaver 7.4
  • SAP NetWeaver 7.5
  • SAP enhancement package 1 for SAP NetWeaver 7.0
  • SAP enhancement package 1 for SAP NetWeaver 7.3
  • SAP enhancement package 1 for SAP NetWeaver 7.5
  • SAP enhancement package 2 for SAP NetWeaver 7.0
  • SAP enhancement package 3 for SAP NetWeaver 7.0

Product

SAP BW/4HANA 1.0 ; SAP BW/4HANA 2.0 ; SAP NetWeaver 2004 ; SAP NetWeaver 7.0 ; SAP NetWeaver 7.3 ; SAP NetWeaver 7.4 ; SAP NetWeaver 7.5 ; SAP enhancement package 1 for SAP NetWeaver 7.0 ; SAP enhancement package 1 for SAP NetWeaver 7.3 ; SAP enhancement package 2 for SAP NetWeaver 7.0 ; SAP enhancement package 3 for SAP NetWeaver 7.0

Keywords

Business Warehouse, BW, 3.5, 7.01, 7.02, 7.03, 7.31, 7.4, 7.5, 7.51 , KBA , BW-BEX-OT-MDX , MDX,OLAP-BAPI,OLE DB for OLAP , BW4-AE-API-MDX , Multidimensional Expressions , How To

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