|
Due to the nature of the
project, consistency, urgency, accuracy and efficiency are top
priorities to the whole project, therefore, essential improvement on
data format, query efficiency –semantics, redundancy control, and
efficiency of dictionary as well as the query language nature/
guidelines are necessary to ensure the data dictionary’s proper
functionality in the overall EA structure.
-
Format:
Since data dictionary is a semantic as
well as a definition of data elements, it can evolve into ontology.
As it was mentioned
in the beginning that it is a web-based solution, it might be a good
idea to use universally compatible standards such as XML as web
service schema for data reuse ease and domain integration
conveniences.
-
Query Efficiency: Semantics
well defined. As mentioned above, the accuracy of the data in
this particular project is essential to the timeliness of decision
making and implementation processes. Semantic integrity is the way to
prevent errors in data during data run-time.
A
semantic integrity constraint specifies what states and state
transitions are allowed in the database to reflect the real
situation. Three general constraints are as follows:
-
Row constraints
-
Table constraints
-
Inter-table constraints -
Consider rows from at least two tables, such as foreign key
constraint.
In
addition to the general constraints, when evaluating from a DB
states point of view, state oriented constraints are:
-
State constraints
-
State transition
constraints
-
State sequence
Below is a comparison of
integrity supported by different common commercial RDBS:

-
Redundancy Control:
Due to the fact that the web portal is the exchange center of all
information flow, reduce data redundancies and inconsistencies are
crucial. It is said that in a distributed system dictionary proper
cataloging techniques can efficiently reduce redundancy issues.
In our
project, for a set of distributed database systems, automated
procedures which performs functions in the distributed database
dictionary can be proposed to implement on the distributed data base
management system or part of network operating systems or ad hoc to
ensure information consistency and reduce redundancy.
-
Efficiency of Dictionary:
For the dynamic nature of the DBs and data involved in the project,
and the required data might belong to either single or several
different DBs, the necessity to have both global and local dictionary
under one network dictionary for distributed dictionary on centralized
systems. ( shown in the picture below)

-
About BrioQuery:
- Two types of table: Fact table
and dimension table, can’t join fact tables to fact tables; join
Dimension tables to Fact table(s)
- Use same name keys to join
Dimension tables to a Fact table, i.e. join Cost Collector Key on the
Dimension table to Cost Collector key on the Fact table.
- Different Fact Tables can reuse
the same Dimension tables, i.e. if user is familiar with the GL
ACCOUNT REPORT table, this table can be reused to create many
different stars.
- Only one join is allowed between
any two tables
- In a query, all tables have to be
joined in order to process.
|