New answers tagged data-warehouse
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Ok, in the Table A/Table B scenario you outline, we have three possibilities:
Table A and Table B update/insert at the same time - existing logic works
Table A XOR Table B updates - can locate record based on ColA, update only the records for the table received.
Table A XOR Table B inserts - hold the record in staging until the other record arrives. Flag ...
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As with other kinds of indexes, Projection Indexes are there to speed up certain specific queries and operations, (usually at the expense of slower inserts and updates but since this is for data warehousing, it shouldn't be much of a deal).
Grouping together all the values of a single column speeds up aggregate operations involving that column. For example, ...
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I just stumbled on your thread accidentally when searching for some stuff. I just read about this in the Kimball DWH ETL toolkit and I might share it with you. Your mapping table is what they refer to as a 'bridge table'. The extra element that they add is a 'group entity', which avoid a many-to-many join. You might want to check that out. See page 196 of ...
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