N/APosted on - 06/28/2011
Hi guys John Sena is here I am preparing my MCS notes and during studies I am facing few problem and I want to share then with all of you may be anyone can help me in this case explain the use of lookup tables and Aggregate tables. Describe the foreign key columns in fact table and dimension table. Waiting for good answer.
Use of lookup tables and Aggregate tables
Hello Rizwan is here for your help.
An aggregate table contains summarized view of data. Lookup tables, using the primary key of the target, allow updating of records based on the lookup condition. At the time of updating the data warehouse, a lookup table is used. When placed on the fact table or warehouse based upon the primary key of the target, the update is takes place only by allowing new records or updated records depending upon the condition of lookup. The materialized views are aggregate tables. It contains summarized data. For example, to generate sales reports on weekly or monthly or yearly basis instead of daily basis of an application, the date values are aggregated into week values, week values are aggregated into month values and month values into year values.
A foreign key of a fact table references other dimension tables. On the other hand, dimension table being a referenced table itself, having foreign key reference from one or more tables.