Informatica Night Update (Delta) Process - More than one Delta Source

Question

We are setup to run a nightly process to update our DW with changes that took place that day in our Siebel OLTP environment. We refer to this as our "Delta Process" since it only updates rows that were chagned in the OLTP or adds new rows that were added to the OLTP. Here is our design:
* In our Siebel OLTP we have a View (V table) created that contains a view of only the records that have been changed since the last "Delta Process". This way we can identify only those rows that need to be updated. So in these examles when you see a table that is prefixed as "S_" it references the entire table and a table prefixed as "V_" references on only the changes to the underlying "S_" table.
Ex 1: Order Item table (S_ORDER_ITEM) joins to Account table (S_ORG_EXT). In the Informtica mapping SQ_JOINER we have a query to SELECT statements that with the results concatentated with a UNION statement. The first SELECT statement selects all rows from the V_ORDER_ITEM joined to the S_ORG_EXT so that all delta rows on the order item view are updated with the corresponding data from the account table (S_ORG_EXT). The second SELECT statement selects all rows from the S_ORG_ITEM joined to the V_ORG_EXT so that all of the order item records that contained account information that changed (per the view) are updated. The result is an updated Order Item DW table that contains all updates made to the Order Item and all any associated Accounts information that is stored on the Order Item.
SELECT A.*, B.* FROM V_ORDER_ITEM A, S_ORG_EXT B WHERE A.ORG_ID = B.ROW_ID
UNION
SELECT A.*, B.* FROM S_ORDER_ITEM A, V_ORG_EXT B WHERE A.ORG_ID = B.ROW_ID
The issues:_
This works fine when you have two tables joined together that contain deltas and you need only on UNION statement. However, the issue is when I have 14 tables joined to S_ORDER_ITEM that contain deltas. This cannot be accomlised (that I can see) with one UNION statement but you would need a UNION statement for each delta table.
Ex 2: This example contains just 3 tables. Order Item table (S_ORDER_ITEM) joins to Account table (S_ORG_EXT) and joins to Product table (S_PROD_INT). In this example you will need to have one UNION for each delta table. If you combine delta tables in the same union you will ultimately end up missing data in the final result. This is because the delta tables will only contain the rows that have changed and if one delta table contains a change and needs to pull data from another delta table that did not contain a corresponding change it will not pull the information.
SELECT A.*, B.*, C.* FROM V_ORDER_ITEM A, S_ORG_EXT B, S_PROD_INT C WHERE A.ORG_ID = B.ROW_ID AND A.PROD_ID = C.ROW_ID
UNION
SELECT A.*, B.*, C.* FROM S_ORDER_ITEM A, V_ORG_EXT B, S_PROD_INT C WHERE A.ORG_ID = B.ROW_ID AND A.PROD_ID = C.ROW_ID
UNION
SELECT A.*, B.*, C.* FROM S_ORDER_ITEM A, S_ORG_EXT B, V_PROD_INT C WHERE A.ORG_ID = B.ROW_ID AND A.PROD_ID = C.ROW_ID
The question:_
1. Is my understanding of how the delta process works correct?
2. Is my understanding that I will need a UNION for each delta table correct?
3. Is there another way to perform the delta process?
My issues are based upon the fact that I join roughly 15 delta tables and select about 100 columns to denormalize the data in the DW. If this is the only option that I have then this will generate an very large and complex query which would be very difficult to manage and udpate.
Thanks...

Answer 1

Hi,
Going thru your post, I find that you have the delta view (V_) and the main table (S_) as drivers, i.e you have two driver tables and hence you make outer joins (w.r.t each other) and make a union to get the complete set of data.
Can you please tell me why both are considered as drivers? Is there a possiability that the V_ view may not have some data but the corresponding S_table might have an update?
Regards,
Bharadwaj Hari