| 摘要 |
Techniques for transforming records prior to loading the records into a data warehouse in an efficient manner. In one embodiment, instead of using lookup transformations, a database operation such as an outer join operation is used to transform records stored in a fact staging table to add foreign keys to the records corresponding to the dimension tables that are associated with a fact table in a data warehouse to which the records are to be loaded. Since the outer join operation is memory intensive, a determination is made as to which dimension tables from the multiple dimension tables associated with the fact table are suitable, from a performance perspective, for the outer join operation. Only those suitable dimension tables are outer joined to the fact staging table to add the foreign keys for the outer joined dimension tables to the fact staging table records. Lookup transformations may be used to add foreign keys to the fact staging table records for the non-suitable dimension tables. The transformed fact records with the foreign keys may then be loaded into the fact table in the data warehouse.
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