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What is Delta data load? -> Consolidated Info


A delta load, by definition, is loading incremental changes to the data. When doing a delta load to a fact table, for example, you perform inserts only... appending the change data to the existing table.

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Delta checks can be done in a number of ways. Different logics can accomplish this. One way is to check if the record exists or not by doing a lookup on the keys. Then if the Keys don't exist then it should be inserted as new records and if the record exist then compare the Hash value of non key attributes of the table which are candidates for change. If the Hash values are different then they are updated records. (For Hash Values you can use MD5 function in Informatica) If you are keeping History (Full History) for the table then it adds a little more complexity in the sense that you have to update the old record and insert a new record for changed data. This can also be done with 2 separate tables with one as current version and another as History version.

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