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From Yonik Seeley <yo...@lucidimagination.com>
Subject Re: Searching for negative numbers very slow
Date Fri, 28 Jan 2011 17:29:18 GMT
On Thu, Jan 27, 2011 at 6:32 PM, Simon Wistow <simon@thegestalt.org> wrote:
> If I do
>
>        qt=dismax
>    fq=uid:1
>
> (or any other positive number) then queries are as quick as normal - in
> the 20ms range.
>
> However, any of
>
>        fq=uid:\-1
>
> or
>
>    fq=uid:[* TO -1]
>
> or
>
>    fq=uid:[-1 to -1]
>
> or
>
>    fq=-uid:[0 TO *]
>
> then queries are incredibly slow - in the 9 *second* range.

That's odd - there should be nothing special about negative numbers.
Here are a couple of ideas:
  - if you have a really big index and querying by a negative number
is much more rare, it could just be that part of the index wasn't
cached by the OS and so the query needs to hit the disk.  This can
happen with any term and a really big index - nothing special for
negatives here.
 - if -1 is a really common value, it can be slower.  is fq=uid:\-2 or
other negative numbers really slow also?

-Yonik
http://lucidimagination.com

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