Feature | Relational | OLAP |
Data Access | Generalized access 1) Relational table(s) 2) Transactional or Summary Table(s) | Multi-dimensional (cross-tab) presentation only 1) Dimensions & Measures 2) Summarized Data |
Presentation | Multi-dimensional and Tabular Reporting | Multi-dimensional only |
Performance Optimization | Pre-summarization required | Rollups are pre-summarized (e.g., monthly data, dimension totals) |
Analysis Capability | Simple 1) Sum 2) Average 3) Count | Advanced Analysis 1) Trending 2) Rankings 3) Exceptions |
Drill Down | 1) Add columns for detail; 2) hierarchy depends on data model) 3) drill to transactions | 1) Hierarchical (parent/child) 2) drill to another dimension 3) drill to relational detail |
Speed | Depends on query and summarization | Fast access due to aggregated storage |