Why hierarchical data to
1. Cleaning the data structure, each layer has its specific scope
2 data lineage tracking, data problems, to quickly locate the source table.
3. reduce duplication of development, there is an intermediate layer data.
4. simplify complex issues, each layer having a specific data layer functionality.
The shielding source abnormality data
tmp temporary table
dim dimension table
DWS (Service Data Layer) Mild summary level (table width) stored fact table
dwd (details data layer) to solve the problem of data quality and integrity issues. Deposit dimension table