[CI] Initial pass at new intro

[Samuel Madden]

All --

I checked in a new intro which I think addresses the concerns about  
related work a little more clearly.  Please look it over and see what  
you think -- Alex, I believe I've captured all the ideas you guys  
mentioned in your mail, but I might have missed on or two.

I'm sure we will need to iterate on this, so pls read and comment!

There are a number of comments throughout the paper where I note  
things that need to fix in light of related work, etc.  Everyone  
should read the BHUNT and CORDS papers and understand the basic  
approaches since they appear to be the state of the art and are  
clearly pretty close to what we have done.

I also made two other changes:

1) A new title, making the scheme sound less like a new index and more  
like a way to exploit soft function dependencies at query execution time

2) Changed CI to CT (correlation table), so that it doesn't seem as  
much like we are proposing a new index (which we aren't.)

  I think we need to clean up our story re: unclustered B+trees a  
little more -- they aren't really a competitive technique, just  
another way to exploit correlations (rather than predicate  
introduction) once correlations have been found.  Problem is that one  
could use an existing tool like CORDS and then create indices on the  
unclustered attributes which might be a win.

We need to say if there is anything about c_per_u / our estimation of  
c_per_u that is different / better than CORDS.  If not we should cut  
down sections 3 and 4 and say we use the same method as CORDS so that  
we can dedicate more space to bucketing and multicolumn search in  
section 5.

Also, there are some references to CT in the figures that I couldn't  
fix -- if one of you could take care of that, that'd be great.



-Sam