Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Adjoined Dimension Columns (ADC)<br />
<br />
<br />
<br />
<br />
<br />
<br />
To use columns of Star Schema Dimension tables in MDC as<br />
Cube Axes we adjoin copies of Dimension columns to Fact table<br />
We call this “ADC”: Adjoined Dimension Columns for Cube Axes<br />
Only 3-5 columns adjoined of relatively low cardinality, since the<br />
number of Cells is the product of table Axis column values<br />
Why is low cardinality important?<br />
Each Cell (or Block of a Cell) must sit on a MB of disk or more,<br />
so sequential access in Cell swamps seek time between Cells<br />
(DB2 MDC documents don’t describe this, but that’s the idea)<br />
The ADC approach generalizes to DBMS without MDC if we sort<br />
Fact table by concatenation of adjoined columns<br />
We explain all this and measure performance in what follows<br />
40
Change language