Hands-On Procedure
As we
noted in the last section, we use Incremental Updates to append new data
to a cube - more precisely to a single partition of a cube - and to update the
aggregations involved. Let's take a look at how we manage the process with the
MSAS tool that is provided to manage this operation, the Incremental Update
Wizard.
We
will use, in our practice example a copy of one of our sample cubes, the Budget
Cube. You can skip the section immediately following, where we copy the
cube, if you prefer to perform it with the actual sample Budget cube
(you can always restore the cube from the .cab archive that comes along with
the MSAS installation, or from the original CD itself - see the Books
Online for the process). Or, if you prefer, simply follow along with
another cube of your choice (realizing that results I illustrate, etc., will,
of course, differ for another cube).
Preparation
Make
a Copy of the Budget Cube and Prepare it for an Incremental Update
1.
Open Analysis
Manager, beginning at the Start menu.
2.
Expand the Analysis
Servers folder by clicking the "+" sign to its immediate
left.
Our
server(s) appear.
3.
Expand the
desired server.
Our
database(s) appear.
4.
Expand the FoodMart
2000 database.
5.
Expand the Cubes
folder.
The
sample cubes appear,
as shown in Illustration 1.
Illustration 1: The
Sample Cubes in the FoodMart2000 Database
NOTE: Your databases / cube tree may differ, depending upon
the activities you have performed since the installation of MSAS (and the
simultaneous creation of the original set of sample cubes). Should you want or
need to restore the cubes to their original state, simply restore the database
under consideration. For instructions, see the MSSQL Server 2000 / MSAS Books
Online.
6.
Right-click on
the Budget sample cube.
Working
with a copy of the sample Budget cube will allow us to maintain our
existing Budget sample cube in its original condition.
7.
Select Copy
from the context menu that appears.
8.
Right-click on
the Cubes folder.
9.
Select Paste
from the context menu that appears.
The Duplicate
Name dialog appears.
As we
have noted in other articles, we cannot have two cubes of the same name in a
given MSAS database.
10.
Type the
following into the Name box of the Duplicate Name dialog:
IncrUpdate
The Duplicate
Name dialog appears, with our modification, as depicted in Illustration 2.
Illustration 2: The
Duplicate Name Dialog, with New Name
TIP: As I have mentioned elsewhere in
the series, this is also an excellent way of renaming a cube (a "rename"
capability is not available here): Simply create a duplicate, give it the name
to which you wish to rename the old cube, and then delete the old cube. (This
also works for MSAS databases.)
11.
Click OK
to save the name change.
The new
cube appears in the cube tree, among those already in place. We now have a
copy of the Budget cube, IncrUpdate, as shown in Illustration
3, upon which we can perform our exercise with the Incremental Update
Wizard.
Illustration 3: The Budget
Cube Clone, IncrUpdate, Appears
As we
learned in several of my other articles, where we made "clones" of
existing sample cubes, when
we make a copy of an existing sample cube, we copy the structure exactly as it
exists for the original sample.
One
component critical to on-going processing with a given sample cube, however,
cannot physically be a part of our cloning process - the Query log
entries that relate to the history of the copied cube cannot accompany
the cloned cube; the entries are identified in the Query log database
(see MSAS
Administration and Optimization: Simple Cube Usage Analysis and MSAS
Administration and Optimization: Toward More Sophisticated Analysis for more information regarding
the Query log) as belonging to the cube that generated them.
This
leaves MSAS a bit perplexed (at least with regard to the "processed status"
of the cube) - it has a cube structure in its midst that, while physically
circumspect with regard to its structure, "has no past." Therefore,
when we attempt to process the cube, MSAS "looks upon him, and knows him
not." It therefore assumes - actually, it mandates - Full Processing.
We will humor MSAS and do a quick Full Process, so that we can continue
our examination of Incremental Updates - Keep in mind that this is only
a preparatory step, and may not be encountered in the "real world."
We will "register"
the clone with MSAS - at least from the perspective of the Query log, by
taking the following steps:
12.
Right-click the
new IncrUpdate cube.
13.
Select Process
from the context menu that appears, as partially shown in Illustration 4.
Illustration 4: Select
Process from the Context Menu (Partial View)
The Process
a Cube - Select the processing method dialog appears, as depicted in Illustration
5.
Illustration 5: The Select
the Processing Method Dialog
Full
Processing is the
default (the other options are disabled), as the IncrUpdate cube
has never been processed, at least from the perspective of history (none
for the clone, at present).
14.
Leaving
settings at default, click OK.
Processing begins, and runs rapidly, as
evidenced by the Process viewer's presentation of processing log events
in real time. Processing ends rather quickly and the success of the
evolution is indicated by the appearance of the Processing Completed Successfully
message (in green letters) at the bottom of the viewer, as shown in Illustration
6.
Illustration 6: Indication
of Successful Processing
We are
returned to Analysis Manager, having prepared the cube for an Incremental Update
(based upon the fact that it was a clone with no history).
Next, let's
do some preparation to make the process work as it would in a real Incremental
Update. For this to be simulated, we will need to build a small set of
data to treat as the "add' source of the Incremental Update.
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