Database Reference
In-Depth Information
Figure 7.21
A dictionary hierarchy for Geography in ASOsamp. (From Oracle Essbase Administration Services.
With permission.)
7.6.2.6 “Dictionary” Hierarchies
Sometimes your users want to see all of the members
alphabetically or maybe alphabetically by description, or even sorted by some other
method. While it would seem the job of your query system to do this, there is little
cost to adding a Dynamic hierarchy with just this kind of arrangement. The only cost
will be to the size of the outline page file. If you use label-only headings, you will be
ensured that there is no inadvertent cost of rolling up members when someone tries to
drill down on what really should be an information-only hierarchy. See Figure 7.21 for
a cube with a dictionary hierarchy for the cities in the [geography] dimension.
7.7 tips to improve Data loaDing anD
aggregation perFormanCe
The two best and simplest ways to increase load performance are dealt with in the
Essbase Technical Reference Manual.
They include:
1. use parallel load streams
2. Increase the settings for DLthrEADSPrEPArE and DLthrEADSWrItE
This will increase performance, but you still will be limited by the bandwidth of your
computer's I/o connections and/or of the I/o device itself. At some point, the people
who manage your network or SAn (storage area network) may start to complain about
your use of resources. It can be expensive or impossible to increase the I/o through-
put, but relatively speaking, with today's computers, it is not difficult to add processing
power. Therefore, the answer is once more to maximize the use of:
Pop's rule: “Computers do arithmetic very fast, but they don't like to run errands.”
use operating system level compression on your input files to reduce the amount
of data that has to be pushed through the limited bandwidth. you also can speed up
Aggregation and even the initial loading of your cubes into memory (after system restarts,
for instance) by compressing the .dat files that house your loaded data. Essentially, you
are just implementing the ASo equivalent of BSo compression. When doing so, it is
important to not set compression on the file objects themselves, but on the subdirectories
in which they will be created. otherwise, you will lose the setting whenever you clear the
data and reload. It is important to remember to set it on both the “default” directory and
on any other tablespaces not in your home APP directory
,
including the TEMP
tablespace.
