Database Reference
In-Depth Information
Figure 4.1
Sample.Basic in an hourglass arrangement. (From Oracle Essbase Administration Services. With permission.)
Figure 4.2
Hourglass calc all application log.
Figure 4.2 is the application log output of a Calc All. It tells us that the anchor dimen-
sion for the calculator cache is market. The calculation generated 394 writes and 1574
reads of the sparse dimensions.
The other common outline format is called the hourglass on a stick and also is
known as the lollipop, as shown in Figure 4.3. With this arrangement, the nonaggre-
gating sparse dimensions are moved to the end of the outline file following the largest
dimensions.
moving the nonaggregating dimensions accomplishes two things. First, it reduces
the number of reads and writes during the calculation possibly reducing calcula-
tion time. Secondly, the anchor dimension changes to the last dimension allowing
the larger dimension to be included in the calculator cache bitmap. In theory, this
should result in faster aggregations. The downside is that placing the large dimen-
sion in the bitmap eliminates any chance of using multiple bitmaps. In most cases,
the database will be too large for multiple bitmaps, anyway. With hourglass on a stick
format, there were 242 and 1220 sparse dimensions writes and reads, respectively, as
shown in Figure 4.4.
