Performing the Assessment
Data warehouse assessment is most effectively performed using a systematic and proven process. Figure 2 illustrates this process and the value derived from it. The following steps provide an overview of the process by which a proto-typical data warehouse assessment is executed using the multiple-perspectives method. The usual team size is three-to-four senior data warehousing analysts who collectively have expertise in all of the identified areas of assessment.
Figure 2: The Data Warehouse Assessment Process
Initial Parallel Investigation
Identify and prioritize executive and management reporting and analysis needs, priorities, constraints and expectations. As discussed, these are typically not well documented, if known at all. At minimum, known and documented business requirements will need to be validated. A series of structured interviews with primary stakeholders works well, followed by a group session to validate, synthesize and prioritize findings.
In parallel with the review of management needs to support the business assessment, an initial review of documents and identification of potential issues can be performed for each of the remaining perspectives. While findings are ultimately interdependent, and particularly dependent on business needs, this initial investigation is an essential data gathering step, and early comparison against benchmarks and best practices is informative. A discussion of the benchmarks is beyond the scope of this article. (Best practices and benchmarks could easily demand an entirely separate series of articles.) Good references for best practices are available in TDWI publications and other literature. Suffice it to state that you should investigate, identify, and have at hand a set of benchmarks against which your own projects and practices will be assessed.
Initial Outputs:
List of prioritized business information needs
Understanding of the information, technology, organization, methodology and project management context.
Initial identification of key problems in each area.
List of what data is available is available in the current DW and any limitations on its completeness, accessibility, data quality.
Gap Analysis
Map the prioritized business information needs against the current warehouse in terms of data availability. This establishes a view of key gaps from the perspective of business need.
Map prioritized business information needs against identified architectural (and possibly organizational) problems. This is a mapping of information needs to architectural issues that inhibit meeting the business needs, and whose resolution would significantly improve delivery of required business information and analysis capabilities. This mapping provides a sense of which architectural issues have the greatest adverse impact on the business and are most urgent to address.
Methodology and project management gaps, and some of the organizational considerations, may not readily map to specific business priorities. These are more global in nature, and issues in this area are likely to have broad impact across all business needs and priorities. Issues from these perspectives are better suited to qualitative, rather than quantitative, analysis of impact.
Identify Solution Sets
Identify an initial list of potential solutions to addressing warehousing problems and correspondingly impacted business needs. This activity involves a subjective analysis of problem affinity analysis based on the earlier mapping. Evaluation of affinity leads to parsing of logically distinct solutions.
Refine and consolidate the set of logical, prioritized solutions based on
Contributions to addressing prioritized business needs.
Contributions to addressing highest impact architectural problems.
Logical groupings of functionality based on architectural feasibility and technical cohesion.
Organizational capability to implement.
High level estimates of time and cost.
Package and Present Recommendations
This involves:
Compilation and final documentation of analysis.
Presentation of findings.
Validation of recommendations with management.
Decisions on which solution set(s) to pursue.
