Re: [HACKERS] What about LIMIT in SELECT ?

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От Bruce Momjian
Тема Re: [HACKERS] What about LIMIT in SELECT ?
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Msg-id 199810201645.MAA07946@candle.pha.pa.us
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Ответ на Re: [HACKERS] What about LIMIT in SELECT ?  (jwieck@debis.com (Jan Wieck))
Ответы Re: [HACKERS] What about LIMIT in SELECT ?
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>     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,
Pennsylvania19026
 


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