2/6/19: oltp vs. olap: http://holowczak. com/introduction-data-warehousing, oltp (online transaction processing) [ came out of theory , highly normalized schema, no redundancies, optimized for writing. Mostly adding to the db: pre-defined queries (system anticipates these queries, maintains recent data (not much more than one year of data). More data, longer for queries: older data is archived. Integrate data from multiple business functions (getting a water bottle from a shelf example. Production, shipping costs, etc: how did we get from oltp olap, mainframe took while to program, common business language (cobol). All issues should have been solved through cobol, but it was still difficult to understand. Business people did not know how to use it: sql created. Gets smart people to make views over the data. People still didn"t know how to type this: dss. Kept disrupting the data that was being written. Executives were last to find out in this chain: eis.