David E. Wheeler wrote:
> On Mar 27, 2009, at 6:40 PM, Bruce Momjian wrote:
>
> > Thanks, text updated:
> >
> > While semi-joins merely replace existing IN joins, anti-joins
> > are a new capability for NOT EXISTS clauses (Tom) This improves
> > optimization possibilities.
>
> I'm not enough of a relational algebra geek to really understand what
> that means. Will there be a link or something to some documentation or
> even, *gasp*, a blog entry explaining what this means and why it's
> important?
Uh, not really; the optimizer stuff is usually quite vague and Tom
might end update removing it once he goes over the release note anyway
(he has in the past). I documented it because it is a user-visible
change, I think, becuase it might show up in EXPLAIN.
-- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB
http://enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +