This figure illustrates the comparisons between OLTP (complex data structures) and data warehousing (multidimensional data structure) environment:

• indexes: OLTP have few while data warehouses have many

• joins: OLTP have many while data warehouses have some

• duplicated data: OLTP have normalized data while data warehouses have denormalized data

• derived data and aggregates: OLTP is rare while data warehouses are common