Efficient Processing of OLAP Queries.

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 Efficient Processing of OLAP Queries

The purpose of materializing cuboids and constructing OLAP index structures is to speed up query processing in data cubes. Given materialized views, query processing should proceed as follows:

I. Determine which operations should be performed on the available cuboids:

This involves transforming any selection, projection, roll-up (group-by), and drill-down operations specified in the query into the corresponding SQL and/or OLAP operations. For example, slicing and dicing a data cube may correspond to selection and/or projection operations on a materialized cuboid.


2. Determine to which materialized cuboid(s) the relevant operations should be applied: 

This involves identifying all of the materialized cuboids that may potentially be used to answer the query, pruning the set using knowledge of "dominance” relationships among the cuboids, and estimating the costs of using the remaining materialized cuboids and selecting the cuboid with the least cost.






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