Indexes are a different animal than regular LFs. A radix index, for example, is WAAAAY different than a old style LF or even an SQL View, even though it says it's a LF. Another reason why I don't like the use of legacy AS400 object names with SQL objects.
The reason why you got MUCH better performance with an index created from the Index Advisor, the access path only had to traverse less than 50% of the table rows, if that, vs a table scan (way bad). It is also possible the access path only did an index scan getting all the data to service your "query" or whatever, and it didn't even have to access the data in the table at all.
Definitely read the manual(s) on performance and indexes and performance tuning to help you get the most out of DB2. These are fundamentals on other DB2s and ORACLE, etc.
This mailing list archive is Copyright 1997-2019 by midrange.com and David Gibbs as a compilation work. Use of the archive is restricted to research of a business or technical nature. Any other uses are prohibited. Full details are available on our policy page. If you have questions about this, please contact