Re: [HACKERS] WARM and indirect indexes

Bruce Momjian wrote:

> 1.  What percentage speedup is the _average_ user going to get?  You
> have to consider people who will use indirect indexes who get no benefit
> or a net slowdown, and users who will get a benefit.
> 
> 2.  What percentage of users are going to use indirect indexes?
> 
> So, for #1 you might have users who are getting +1%, +50%, and -20%, so
> maybe +10% average, and for #2 you might have 0.1%.  When you multiply
> them out, you get 0.01% average improvement per installation, which is
> very small.  Obviously, these are just wild guesses, but this is just to
> make a point.

Perhaps not many users will require indirect indexes; but for those that
do, the feature might be invaluable.  We don't do only things that
benefit everybody -- some features are there to satisfy small
populations ("snapshot too old" is a recent example).  We should of
course do, and perhaps even favor doing things that benefit everybody,
but should also do the other things.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services