Seeking workarounds to give effect of INSERT...SELECT...RETURNING

Question

What is the most efficient way to get record counts from subqueries within an INSERT INTO () SELECT () statement on Oracle 11g? I feel like I'm too close to the code to see the obvious answer here.
Background:
I am building a dynamic data quality testing framework, wherein stored procedures call SQL blocks for specific tests from a table in accordance with the test identifier and boundary parameters passed in. The blocks: (a) log an entry for the test activity, (b) prepare a "should be" snapshot of the data in a staging table, (c) perform a source-to-target comparison, dropping discrepancies into a results table, and then (d) update the test activity record with the result counts.
Action (c) is accomplished by selecting a union of the "should be" data from a staging table and the "as is" data from a target table or MV, dropping all exact duplicate records so that only mismatches (errors) remain, and inserting those details in a results table, labeling each record with whether it comes from the source ("should be") or target ("as is") subquery. I am trying to not to hit the DB twice (performance concerns), so I am running the source and target rowcounts on the "should be" and "as is" subqueries using COUNT () OVER PARTITION. Currently I dump these counts into the results table, but if there are zero defects, there are no results records to dump them into. I want to select these counts into bind variables, but for some reason I am not succeeding.
I am currently trying to use the Method 2 workaround described in [http://www.oracle-developer.net/display.php?id=413|http://www.oracle-developer.net/display.php?id=413] , but can't seem to get my query block to adapt to the INSERT ALL format.
Here's a shell of the analysis block without trying to integrate the Method 2 workaround:
DECLARE
StartDate DATE;
EndDate DATE;
TEST_KEY NUMBER;
BEGIN
INSERT INTO TEST_EVENT_DETAIL
    (TEST_EVENT_KEY,TEST_EVENT_DETAIL_KEY,COLUMN1,COLUMN2,COLUMN3,COLUMN4,
    COLUMN5, COLUMN6)
SELECT
    TEST_KEY as TEST_EVENT_KEY,
    TEST_EVENT_DETAIL_SEQ.NEXTVAL AS TEST_EVENT_DETAIL_KEY,
    RESULTS.TABLENAME as COLUMN1,
    RESULTS.COLUMNNAME1 as COLUMN2,
    RESULTS.COLUMNNAME2 as COLUMN3,
    RESULTS.source_count as COLUMN4,
    RESULTS.target_count as COLUMN5,
    null as COLUMN6  -- there are more generic columns, this is just an example; columns not used by a particular test are filled with nulls
FROM
(SELECT MIN(TABLENAME) as TABLENAME,
    min(source_count) as source_count,
    min(target_count) as target_count,
    COLUMNNAME1,
    COLUMNNAME2
  FROM
(SELECT TABLENAME as TABLENAME,
    case when TABLENAME='SOURCE' then count(TABLENAME) over (partition by TABLENAME) else null end source_count,
    case when TABLENAME='TARGET' then count(TABLENAME) over (partition by TABLENAME) else null end target_count,
    COLUMNNAME1,
    COLUMNNAME2
  from
/** Source Data **/
SELECT 'SOURCE' as TABLENAME,
    COLUMNNAME1,
    COLUMNNAME2
   FROM TEST_EVENT_STAGE A
WHERE A.TEST_EVENT_KEY=TEST_KEY
  UNION ALL
/** Target Data **/
  SELECT 'TARGET' as TABLENAME,
    COLUMNNAME1,
    COLUMNNAME2
  FROM TABLENAME B
  WHERE ______(criteria for target query goes here)_______
) TMP
GROUP BY COLUMNNAME1, COLUMNNAME2
HAVING COUNT(*) = 1 -- this drops out all records that don't match
ORDER BY COLUMNNAME1, COLUMNNAME2, TABLENAME ASC
) RESULTS;
END;What am I missing here? It should be simple to get these values into a variable, but whatever I try gives me nulls.

Answer 1

Figured it out,...needed to add a level and get MAX across all partitions, and then use a "zero defects" entry to capture it for later harvesting. (The "zero defects" entry is removed if there are other records for that test event stored in the details table.)
Here's what it evolved into:
DECLARE
vPROCESSSTARTTIME   DATE;
vSTARTDATETIME DATE;
vENDDATETIME DATE;
vTESTEVENTKEY NUMBER;
source_count NUMBER;
target_count NUMBER;
BEGIN
INSERT INTO TEST_EVENT_DETAIL
       (TEST_EVENT_KEY,TEST_EVENT_DETAIL_KEY,PROCESS_START_TIME,COLUMN1,
       COLUMN2,COLUMN3,COLUMN4,COLUMN5,COLUMN6,COLUMN7,COLUMN8,COLUMN9,
       COLUMN10,COLUMN11,COLUMN12,COLUMN13,COLUMN14,COLUMN15,COLUMN16,
       COLUMN17,COLUMN18,COLUMN19,COLUMN20,COLUMN21,COLUMN22,COLUMN23,
       COLUMN24,COLUMN25,COLUMN26,COLUMN27,COLUMN28,COLUMN29,COLUMN30)
SELECT
    vTESTEVENTKEY as TEST_EVENT_KEY,
    TEST_EVENT_DETAIL_SEQ.NEXTVAL AS TEST_EVENT_DETAIL_KEY,
    vPROCESSSTARTTIME as PROCESS_START_TIME,
    vSTARTDATETIME as COLUMN1,
    vENDDATETIME as COLUMN2,
    RESULTS.source_count as COLUMN3,
    RESULTS.target_count as COLUMN4,
    RESULTS.RECORD_SOURCE as COLUMN5,
    RESULTS.columnname as COLUMN6,
    RESULTS.columnname as COLUMN7,
    --continue for the rest of the columns, null for anything unpopulated
    NULL as COLUMN29,
    NULL as COLUMN30
FROM
(SELECT MIN(RECORD_SOURCE) as RECORD_SOURCE,
    min(source_count) as source_count,
    min(target_count) as target_count,
    columnname,
    columnname,
    --continue for the rest of the columns
  FROM
   (SELECT
    MAX(source_count) OVER () as source_count,
    MAX(target_count) OVER () as target_count,
    RECORD_SOURCE,
    columnname,
    columnname,
    --continue for the rest of the columns
  FROM  
(SELECT RECORD_SOURCE as RECORD_SOURCE,
    case when TABLENAME='SOURCE' then count(RECORD_SOURCE) over (partition by RECORD_SOURCE) else 0 end source_count,
    case when TABLENAME='TARGET' then count(RECORD_SOURCE) over (partition by RECORD_SOURCE) else 0 end target_count,
    columnname,
    columnname,
    --continue for the rest of the columns
  from
/** Source Data **/
Select * from
SELECT 'SOURCE' as RECORD_SOURCE,
    A.COLUMN6 as columnname,
    A.COLUMN7 as columnname,
    --continue for the rest of the columns
   FROM TEST_EVENT_STAGE A
WHERE A.TEST_EVENT_KEY=vTESTEVENTKEY
  ) src
  UNION ALL
/** Target Data **/
Select * from
  SELECT 'TARGET' as RECORD_SOURCE,
    B.columnname,
    B.columnname,
    --continue for the rest of the columns
  FROM target_tablename B
  WHERE --criteria as needed
  and B.whatever_DT >= vSTARTDATETIME
  AND B.whatever_DT < vENDDATETIME
  ) tgt
UNION ALL
/** zero defects placeholder record **/
Select * from
  SELECT 'ZERO' as RECORD_SOURCE,
    NULL as columnname,
    NULL as columnname,--continue for the rest of the columns
  FROM dual C
  ) zero
) TMP
GROUP BY columnname,columnname,--continue for the rest of the columns
HAVING COUNT(*) = 1 -- this drops out all records that don't match
ORDER BY columnname,columnname,--continue for the rest of the columns
    RECORD_SOURCE ASC
) RESULTS;
END;