Re: [HACKERS] What about LIMIT in SELECT ?

Bruce Momjian <maillist@candle.pha.pa.us>

From: Bruce Momjian <maillist@candle.pha.pa.us>
To: jwieck@debis.com
Cc: Inoue@tpf.co.jp, jwieck@debis.com, hackers@postgreSQL.org
Date: 1998-10-20T16:45:49Z
Lists: pgsql-hackers
>     Right. As I remember, your solution does basically  the  same
>     as  my  one. It does not change the optimizers decision about
>     the index or if an index at all is used.  So  I  assume  they
>     hook  into  the same position where depending on the order by
>     clause the sort node is added. And that is at the very end of
>     the optimizer.
> 
>     What  you  describe above requires changes in upper levels of
>     optimization.  Doing that is far away from my knowledge about
>     the  optimizer.   And  some of your earlier statements let me
>     think you aren't familiar enough with  it  too.  We  need  at
>     least help from others to do it well.
> 
>     I  don't want to dive that deep into the optimizer. There was
>     a far too long time where the rule system was broken and  got
>     out  of  sync with the parser/optimizer capabilities. I fixed
>     many things in it for 6.4. My first priority now is,  not  to
>     let such a situation come up again.

I agree.  Another good thing is that the LIMIT thing will not require a
dump/reload, so it is a good candidate for a minor release.

-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  maillist@candle.pha.pa.us            |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026