Oracle Plus (+) Joins to ANSI conversion - oracle

Question

I'm in the middle of a warehouse migration from Oracle to SQL Datawarehouse Azure and ran into an issue with this query.
The original query from Oracle - it returns 1872520 rows.
SELECT
*
FROM
STG_REV_APPORTION_CSC_NO t1,
STG_SEP_VL t2,
STG_SEP_VL t3
WHERE
t3.BUSINESS_DATE(+) = t1.BUSINESS_DATE
AND t3.CSC_APP_NO(+) = t1.CSC_APP_NO
AND t3.JOURNEY_NO(+) = t1.JOURNEY_NO
AND t3.PURSE_TXN_CTR(+) = t1.PURSE_TXN_CTR
AND t2.BUSINESS_DATE(+) = t1.BUSINESS_DATE
AND t2.CSC_APP_NO(+) = t1.CSC_APP_NO
AND t2.JOURNEY_NO(+) = t1.JOURNEY_NO
AND
(
t2.TRIP_NO(+) + 1
)
= t1.TRIP_NO
AND
(
t2.MSG_TYPE_CD(+) = 13070
AND t3.MSG_TYPE_CD(+) = 4357
);
Taking clues from documentation, I tried query re-write to ANSI:
SELECT COUNT(*)
FROM STG_REV_APPORTION_CSC_NO t1
RIGHT OUTER JOIN STG_SEP_VL t3 ON t3.BUSINESS_DATE = t1.BUSINESS_DATE
AND t3.CSC_APP_NO = t1.CSC_APP_NO
AND t3.JOURNEY_NO = t1.JOURNEY_NO
AND t3.PURSE_TXN_CTR = t1.PURSE_TXN_CTR
RIGHT OUTER JOIN STG_SEP_VL t2 ON t2.BUSINESS_DATE = t1.BUSINESS_DATE
AND t2.CSC_APP_NO = t1.CSC_APP_NO
AND t2.JOURNEY_NO = t1.JOURNEY_NO
AND (t2.TRIP_NO + 1) = t1.TRIP_NO
WHERE t2.MSG_TYPE_CD = 13070 AND t3.MSG_TYPE_CD = 4357
It returns zero rows. The ANSI version should work on oracle instance - it returns zero rows there too.
I then tried to convert plus join to ANSI using refactor option on toad. I get the following
SELECT *
FROM STG_SEP_VL T2
RIGHT OUTER JOIN STG_REV_APPORTION_CSC_NO T1
ON (T2.BUSINESS_DATE = T1.BUSINESS_DATE)
AND (T2.CSC_APP_NO = T1.CSC_APP_NO)
AND (T2.JOURNEY_NO = T1.JOURNEY_NO)
RIGHT OUTER JOIN STG_SEP_VL T3
ON (T3.PURSE_TXN_CTR = T1.PURSE_TXN_CTR)
AND (T3.BUSINESS_DATE = T1.BUSINESS_DATE)
AND (T3.CSC_APP_NO = T1.CSC_APP_NO)
AND (T3.JOURNEY_NO = T1.JOURNEY_NO)
WHERE ( ( (T2.TRIP_NO /*(+)*/
) + 1) = T1.TRIP_NO)
AND ( ( (T2.MSG_TYPE_CD /*(+)*/
) = 13070) AND ( (T3.MSG_TYPE_CD /*(+)*/
) = 4357));
Now this query should run on Oracle and return the same number of rows before I can run it on SQL Server. But it doesn't - it returns zero rows.
I looked at the explain plan for both of these queries. Here is how (+) join plan looks like:
Here is how ANSI version of this query looks like:
Am I missing something?

Answer 1

Here's what I came up with:
SELECT *
FROM stg_rev_apportion_csc_no t1
LEFT JOIN stg_sep_vl t3
ON t1.business_date = t3.business_date AND
t1.csc_app_no = t3.csc_app_no AND
t1.journey_no = t3.journey_no AND
t1.purse_txn_ctr = t3.purse_txn_no AND
4357 = t3.msg_type_cd
LEFT JOIN stg_sep_vl t2
ON t1.business_date = t2.business_date AND
t1.csc_app_no = t2.csc_app_no AND
t1.journey_no = t2.journey_no AND
t1.trip_no = t2.trip_no + 1 AND
13070 = t2.msg_type_cd;
Tables t2 and t3 are outer joined to t1, so you either list t1 first and do a left join, or list t2 and t3 first and do a right join.

Answer 2

Without sample data it is hard to be sure but I think the where clause is to blame.
Including fields from t2 and t3 in the where clause negates the effect of the outer join, unless you also allow nulls (t2.MSG_TYPE_CD = 13070 OR 2.MSG_TYPE_CD IS NULL). Moving those filters into the join allows non-matching records into the results.
SELECT
COUNT(*)
FROM
STG_REV_APPORTION_CSC_NO t1
RIGHT OUTER JOIN STG_SEP_VL t3 ON t3.BUSINESS_DATE = t1.BUSINESS_DATE
AND t3.CSC_APP_NO = t1.CSC_APP_NO
AND t3.JOURNEY_NO = t1.JOURNEY_NO
AND t3.PURSE_TXN_CTR = t1.PURSE_TXN_CTR
AND t3.MSG_TYPE_CD = 4357
RIGHT OUTER JOIN STG_SEP_VL t2 ON t2.BUSINESS_DATE = t1.BUSINESS_DATE
AND t2.CSC_APP_NO = t1.CSC_APP_NO
AND t2.JOURNEY_NO = t1.JOURNEY_NO
AND (t2.TRIP_NO + 1) = t1.TRIP_NO
AND t2.MSG_TYPE_CD = 13070
;
I'm not 100% convinced this query is correct. I suspect the right outer joins should be replaced with left outer joins. That would return every record from t1 and only those from t2 and t3 that match.

Answer 3

It is difficult to find the exact reason for this mismatch but I think you have interchanged the joining condition for the column PURSE_TXN_CTR in table STG_SEP_VL.
SELECT *
FROM STG_REV_APPORTION_CSC_NO t1
RIGHT
JOIN STG_SEP_VL t2
ON t2.BUSINESS_DATE = t1.BUSINESS_DATE
AND t2.CSC_APP_NO = t1.CSC_APP_NO
AND t2.JOURNEY_NO = t1.JOURNEY_NO
AND ( t2.TRIP_NO + 1 ) = t1.TRIP_NO
RIGHT
JOIN STG_SEP_VL t3
ON t3.BUSINESS_DATE = t1.BUSINESS_DATE
AND t3.CSC_APP_NO = t1.CSC_APP_NO
AND t3.JOURNEY_NO = t1.JOURNEY_NO
AND t3.PURSE_TXN_CTR = t1.PURSE_TXN_CTR
WHERE ( t2.MSG_TYPE_CD = 13070 AND t3.MSG_TYPE_CD = 4357 );