Re: Critical performance problems on large databases

Oleg Bartunov wrote:

> On Thu, 11 Apr 2002, Bruce Momjian wrote:
>
>
>>Oleg Bartunov wrote:
>>
>>>The big issue with LIMIT,OFFSET is that it still use all rows
>>>for sorting. I already suggested to use partial sorting to avoid
>>>sorting all rows if one selected only first 20 row, for example.
>>>It's very important for Web applications because web users usually
>>>read first 1-2 pages. Our experimnets have shown 6 times performance
>>>win when using partial sorting.
>>>
>>We do have this TODO item:
>>
>>    * Allow ORDER BY ... LIMIT to select top values without sort or index
>>      using a sequential scan for highest/lowest values
>>
>>
>
> looks too complex to me :-) I like partial sorting, but it's not
> important.


Oleg, I might argee. I might even take some of this one. But I
think a first step would be for you to put your libpsort and
the pacth "out there" so that someone could just look and try
and see if taking the time to do what needs to be done is feasible
with this. If you can put up your lib and patch and documentation
(even crude notes)) onto a web site, that would be a good start.

regards
-Gunther




--
Gunther Schadow, M.D., Ph.D.                    gschadow@regenstrief.org
Medical Information Scientist      Regenstrief Institute for Health Care
Adjunct Assistant Professor        Indiana University School of Medicine
tel:1(317)630-7960                         http://aurora.regenstrief.org