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Online Analytical Processing (OLAP) are the methods used to design systems and schemas widely used in Data Mining systems, and Business Intelligence. OLAP is characterized by relatively low volume of transactions. However, queries are often very complex and involve aggregations across multiple datasets. The performance of OLAP Systems is measured by response times. (to generate a report). The typical OLAP database stores aggregated, post-processed, historical data in a multi-dimensional schema. (usually star schema, snowflake). Consider OTLP vs OLAP

A common short-cut is to join all relational tables together into one large table, frequently resulting in a huge view/table. For mid-sized datawarehouses, this may be feasible, but for very large data-warehouses, data marts are needed.

Data cubes are then created from this.

There are variants of OLAP. These are: