Help with displaying BLOBs in OBIEE 11g

Question

I am trying to get OBIEE 11g to display photographs in an Analysis report. I know BLOB fields are not supported, and I have been reading posts on this board and following examples on internet sites that try to get round this problem. But, try as I might, I cannot get those pesky photos to display.
Below are all the steps I have followed. Sorry that there is a lot to read, but I was hoping that somebody has been successful in doing this, and may spot something in one of my steps that I am doing wrong.
ORACLE TRANSACTIONAL SOURCE_
Table : EMPL_PHOTO
Fields:
USN VARCHAR2(11) ( Unique Key )
EMPLOYEE_PHOTO BLOB ( I think the photos are stored as 'png' )
ORACLE WAREHOUSE SOURCE_
Table : D_PERSON_PHOTO_LKUP
Fields :
PERSON_KEY     NUMBER(38,0) ( Primary Key - Surrogate )
USN     VARCHAR2(11)
PHOTO     CLOB
BLOB to CLOB conversion.
I used this function :
     create or replace function blob_to_clob_base64(p_data in blob)
     return clob
     is
     l_bufsize integer := 16386;
     l_buffer raw(16386);
     l_offset integer default 1;
     l_result clob;
     begin
     dbms_lob.createtemporary(l_result, false, dbms_lob.call);
     loop
     begin
     dbms_lob.read(p_data, l_bufsize, l_offset, l_buffer);
     exception
     when no_data_found then
     exit;
     end;
     l_offset := l_offset + l_bufsize;
     dbms_lob.append(l_result, to_clob(utl_raw.cast_to_varchar2(utl_encode.base64_encode(l_buffer))));
     end loop;
     return l_result;
     end;
     select usn, employee_photo ,
     BLOB_TO_CLOB_BASE64(employee_photo)
     from empl_photo
IN OBIEE ADMINISTRATION TOOL_
*1) Physical Layer*
Added D_PERSON_PHOTO_LKUP from Connection Pool
Left it as 'Cachable'
Didn't join it to any tables
Changed field PHOTO to a 'LONGVARCHAR' length 100000
Set USN as the Key ( not the surrogate key )
*2) BMM Layer*
Dragged D_PERSON_PHOTO_LKUP across.
Renamed it to 'LkUp - Photo'
Ticked the 'lookup table' box
Removed the surrogate key
Kept USN as the Primary key
The icon shows it similar to a Fact table, with a yellow key and green arrow.
On Dimension table D_PERSON_DETAILS (Dim - P01 - Person Details) added a new logical column
Called it 'Photo'
Changed the column source to be derived from an expression.
Set the expression to be :
Lookup(DENSE
"People"."LkUp - Photo"."PHOTO",
"People"."Dim - P01 - Person Details"."USN" )
Icon now shows an 'fx' against it.
Note: This table also had it Surrogate key removed, and USN setting as primary key.
*3) Presentation Layer*
Dragged the new Photo field across.
Saved Repository file, uploaded, and restarted server.
ONLINE OBIEE_
Created a new Analysis.
Selected USN from 'Person Details'
Selected Photo from 'Person Details'
Selected a measure from the Fact table
Under column properties of Photo ( data format ) :
- Ticked 'Override Default Data Format' box
- Set to Image URL
- Custom text format changed to : @[html]"<img alt="" src=""@H"">"
Under column properties of Photo ( edit formula ) :
- Changed to : 'data:image/png;base64,'||"Person Details"."Photo"
The Advanced tab shows the sql as :
     SELECT
     0 s_0,
     "People"."Person Details"."USN" s_1,
     'data:image/png;base64,'||"People"."Person Details"."Photo" s_2,
     "People"."MEASURE"."Count" s_3
     FROM "People"
     ORDER BY 1, 2 ASC NULLS LAST, 3 ASC NULLS LAST
     FETCH FIRST 65001 ROWS ONLY
Going into the 'results' tab, get error message:
+State: HY000. Code: 10058. [NQODBC] [SQL_STATE: HY000] [nQSError: 10058] A general error has occurred. [nQSError: 43113] Message returned from OBIS. [nQSError: 17001] Oracle Error code: 932, message: ORA-00932: inconsistent datatypes: expected - got CLOB at OCI call OCIStmtExecute. [nQSError: 17010] SQL statement preparation failed. (HY000)+
It doesn't seem to be using the Lookup table, but can't work out at which step I have gone wrong.
Any help would be appreciated.
Thanks

Answer 1

Thanks, yes I followed http://docs.oracle.com/cd/E28280_01/bi.1111/e10540/busmodlayer.htm#BGBDBDHI, but when I get to the part of setting the LOOKUP function on th Physical source, only ONE physical source is displayed. I need TWO sources ( The Employee Table, and the Photo LookUp.
I have raised this as an error with Oracle. We are now on OBIEE 11.1.1.7, but Oracle say BLOBS are still not supported in that release. It will be fixed in 11.1.1.8 and it will be backported into 11.1.1.6.11
In the meantime we have abandoned showing Photo's in any of our reports.