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    • Symptoms:
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      Note: This solution is no longer maintained. For the latest information, please refer to our documentation: https://docs.exasol.com/advanced_analytics/skyline.htm

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      Skyline is a new feature in EXASolution 5.0 and is used for finding solutions to problems where multiple criteria are involved in deciding between a large number of choices and there is no definitive method for deciding what is the “best” choice i.e. there is no agreed formula for calculating a "score" for each choice based on weighting the different criteria.

      This means that there are different ways of assessing whether a choice is “good” and often these ways can be contradictory (e.g. price and quality, risk and reward, supply and demand)

      In these circumstances, no computer can possibly choose the “best” solution - choices may be "good" in different ways and it is a matter of personal taste to decide which is the "best".

      Skyline uses an algorithm to filter out a large number of options which are "worse in every way" than some other choice. For example, we can rule out investments funds which have lower return AND higher risk than some other fund.

      This results in a shortlist of “good” choices which can be investigated in more detail.

      Show
      Note: This solution is no longer maintained. For the latest information, please refer to our documentation:  https://docs.exasol.com/advanced_analytics/skyline.htm ------------------------------------------------------------------------------------------------------------------------------------------ Skyline is a new feature in EXASolution 5.0 and is used for finding solutions to problems where multiple criteria are involved in deciding between a large number of choices and there is no definitive method for deciding what is the “best” choice i.e. there is no agreed formula for calculating a "score" for each choice based on weighting the different criteria. This means that there are different ways of assessing whether a choice is “good” and often these ways can be contradictory (e.g. price and quality, risk and reward, supply and demand) In these circumstances, no computer can possibly choose the “best” solution - choices may be "good" in different ways and it is a matter of personal taste to decide which is the "best". Skyline uses an algorithm to filter out a large number of options which are "worse in every way" than some other choice. For example, we can rule out investments funds which have lower return AND higher risk than some other fund. This results in a shortlist of “good” choices which can be investigated in more detail.
    • Explanation:
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      Skyline is implemented in our SQL dialect using a "PREFERRING" clause.

      The full detail of the options available are in the User Manual (section 2.10 "Skyline") but the following examples illustrate some of the possibilities :-

      -- The basic example: rule out all options that have higher risk 
      -- and lower return than some other fund and return a shortlist
      -- of funds for further investigation
      
      SELECT fund_id FROM investments
      PREFERRING (LOW investment_risk PLUS HIGH investment_return);
      
      -- As above, but in cases where the risk and return are the same, 
      -- prefer the fund with the best manager
       
      SELECT fund_id FROM investments
      PREFERRING (LOW investment_risk PLUS HIGH investment_return)
      PRIOR TO (HIGH manager_performance);
      
      -- As above, but choose a shortlist of funds for each market sector
      
      SELECT market_sector, fund_id FROM investments
      PREFERRING (LOW investment_risk PLUS HIGH investment_return)
      PRIOR TO (HIGH manager_performance)
      PARTITION BY market_sector ;
      
      Show
      Skyline is implemented in our SQL dialect using a "PREFERRING" clause. The full detail of the options available are in the User Manual (section 2.10 "Skyline") but the following examples illustrate some of the possibilities :- -- The basic example: rule out all options that have higher risk -- and lower return than some other fund and return a shortlist -- of funds for further investigation SELECT fund_id FROM investments PREFERRING (LOW investment_risk PLUS HIGH investment_return); -- As above, but in cases where the risk and return are the same, -- prefer the fund with the best manager SELECT fund_id FROM investments PREFERRING (LOW investment_risk PLUS HIGH investment_return) PRIOR TO (HIGH manager_performance); -- As above, but choose a shortlist of funds for each market sector SELECT market_sector, fund_id FROM investments PREFERRING (LOW investment_risk PLUS HIGH investment_return) PRIOR TO (HIGH manager_performance) PARTITION BY market_sector ;
    • Solution:
      Hide

      Further detail is available in the User Manual (section 2.10 "Skyline")

      We also have two videos related to Skyline on the EXASOL YouTube channel:

      Show
      Further detail is available in the User Manual (section 2.10 "Skyline") We also have two videos related to Skyline on the EXASOL YouTube channel: This one explains the theory This one works through a practical example in EXAplus
    • Category 1:
      UDFs and In-Database Analytics

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            • Assignee:
              CaptainEXA Captain EXASOL
              Reporter:
              CaptainEXA Captain EXASOL
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