On Querying Data and Metadata in Multiversion Data Warehouse - Data Warehousing Design and Advanced Engineering Applications - page 222

Figure 3. The software architecture of the MVDW prototype

Content Query Interface button). Moreover, one can view a SVQ passed

for execution in a given DW version (available
under the View query button). For every partial
result, one can show or hide metadata describing
schema and dimension instance changes between
adjacent DW versions that are queried (available
under the View changes/Hide changes button).
For example, in Figure 4 metadata describing
changes made to RV4 as compared to RV3 inform
a user that table called Sale in RV3 was renamed
to Poland_Sale in RV4 . In RV5 two products were
reclassified to another VAT category. Common
result contains an integrated result from the three
addressed DW versions.

The results of multiversion queries are presented
in the content query interface as: (1) separate re-
sults of singleversion queries and (2) an integrated
result, if an integration is possible. Additionally,
every result of a SVQ is annotated with version
information and metadata describing changes ap-
plied to a DW schema and the structure of dimen-
sion instances in adjacent DW versions.
The example screen shot of the content query
interface is shown in Figure 4. It is composed of
two panels. The left-hand side panel - an object
navigator allows to browse through DW schema
versions and DW instance versions. The right-hand
side panel - query visualizer is used for visualizing
the results of MVQs.
The screen shot shown in Figure 4 displays
the results of a MVQ that addresses DW versions
from March (denoted as RV3 ) to May (denoted as
RV5 ). As we can observe in Figure 4, each of the
addressed DW versions contains its own partial
result, denoted as Version RV3 , Version RV4 , and
Version RV5 . Every partial result, can be displayed
either in a text form (available under the View data
button) or as a chart (available under the View chart

Metadata Query Interface

The results of metadata queries, both version
queries and object evolution queries, are visual-
ized in the metadata query interface .

Version Query Visualization

As mentioned before, the result of a version query
is a DW version derivation tree. In the tree, we
use different colors for representing different DW