As per my understanding, OLTP is basically based on INSERT, UPDATE, DELETE commands, where as OLAP Based on SELECT command. And processing in OLTP is fast relative to OLAP, because UPDATE is faster than SELECT;
JOINS in OLAP make this even slower, because of more memory movement.
Keeping above in considerations, Then why is it called, It has the ability to create very fast aggregations and complex calculations of data sets in data analysis and data modeling?
expatiation using example would be more helpful.