Re: [HACKERS] Solution for LIMIT cost estimation - Mailing list pgsql-hackers

From Chris Bitmead
Subject Re: [HACKERS] Solution for LIMIT cost estimation
Date
Msg-id 38A79295.BF844BE7@nimrod.itg.telecom.com.au
Whole thread Raw
In response to Solution for LIMIT cost estimation  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [HACKERS] Solution for LIMIT cost estimation
List pgsql-hackers
Don Baccus wrote:
> 
> At 03:32 PM 2/14/00 +1100, Chris Bitmead wrote:
> 
> >I agree you should probably go the whole hog one way or the other. I
> >think
> >ignoring offset+limit is a useful option, but like I said at the
> >beginning, it doesn't bother me _that_ much.
> 
> It should bother you that folks who understand how SQL works might
> be penalized in order to insulate the fact that those who don't know
> how SQL works from an understanding of their own ignorance...
> 
> Shouldn't we be more concerned with folks who bother to read an
> SQL primer?  Or Oracle or Informix docs on SQL?

LIMIT is not SQL, both as a technical fact, and philosophically
because it reaches outside of set theory. What LIMIT does without
ORDER BY is non-deterministic, and therefore a subjective matter of
what is the most useful: a faster answer, or a more consistant answer.
My predudices are caused by what I use PostgreSQL for, which is
more favourable to the latter.


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