17. Consists of a series of conformed dimensional data marts
18. Each Data Mart represents a difference business process.
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20. In General only a small subset of users will need true ad-hoc query capability
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Editor's Notes
These may seem simple but these principles are the foundation for the deign methodology.For business users to be able to navigate the system the tools and most importantly the data must simple and easy to use.Consistency requires a thorough ETL process to cleanse & conform the data.Change is inevitable. We need a design that is resilient to change.Security …Must have the right data in order to support decisions this means up front analysis focuses on the business need
Ultimately if any system doesn’t satisfy some business need, it is of no value and is a failure.
Go through Each Component.
Discuss Each bullet point
Discuss Each bullet pointExamples of Cleansing activities:MisspellingsFormattingCapitalization ConformanceEmphasize that users are forbidden from executing queries on these data.3NF Data is to complex for most users.3NF is not optimized for query performance.
Discuss Each bullet pointDiscuss what it means to be a conformed data martPoint out that dimensional modeling will be discussion in detail later on
Discuss Each bullet pointSpecify the examples in this diagram and what role they play
Discuss why additive facts are most usefulDescribe Semi additive factsNote that the primary key is the combo of all the foreign keys. A ROWID add little value and the index probably would be of any us either.
Attribute description should avoid cryptic abbreviationsMinimize the use of codesShow the denormalized nature of one of these dimensions.Denormalized dimensions provide the following benefits.Simplified structure for non technical usersBetter query performanceSince dimensions typically have a relatively few number of rows the impact of reduced storage efficiency is minimal
Walk through SCD2 example using dimensional model above
Walk through the date dimension in the POC example
Point out that the POCGLTransaction fact table is a transaction fact tableAnd the budget table is a periodic snapshot.