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Data Warehouse |
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[SSAS] |
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Questions: |
Notes: |
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What are the Storage Modes for Dimensions? |
The storage modes for dimensions are MOLAP and ROLAP.
Dimensions can’t use HOLAP because dimensions do not perform aggregations.
Therefore, dimensions can have their data physically stored in their partition files via MOLAP.
Or dimensions can read their data from the relational database via ROLAP. |
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What are Aggregations? |
Aggregations are precalculated summaries of data that improve query response time by having the answers ready before the questions are asked.
Precalculation of all possible aggregations in a cube results in the fastest possible response time for all queries. However, the storage and processing time required for the aggregations can be substantial. |
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What are the different Process Modes? |
The different Process Modes include:
I. Process Structure → Process Data → Process Indexes & Aggregations II. Does incremental ETL
I. Only processes the structure of the cube or dimension and not its data
I. Drops old data and processes all data
I. Does incremental ETL to bring in only changed data in the cube or partition
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