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From Shai Erera <ser...@gmail.com>
Subject Re: Some thoughts around the use of reader.isDeleted and hasDeletions
Date Wed, 10 Jun 2009 15:16:03 GMT
>
> it makes sense because isDeleted() is essentially the *only* thing
> being done in the loop, and hence we can eliminate the loop entirely
>

You mean that in case there is a matching segment, we can call
matchingVectorsReader.rawDocs(rawDocLengths, rawDocLengths2, 0, maxDoc)?
But in case it does not have a matching segment, we'd still need to iterate
on the docs, and copy the term vectors one by one, right?

I'm not very familiar w/ the code, so I'd like to confirm my understanding.

Shai

On Tue, Jun 9, 2009 at 9:54 PM, Yonik Seeley <
yonik.seeley@lucidimagination.com> wrote:

> 2009/6/9 Shai Erera <serera@gmail.com>:
> >> If there are no deletions, it's just a null pointer check, right?
> >
> > Well ... one null pointer check here, one null pointer check there and at
> > some point you will see a difference. My point wasn't the null pointer
> check
> > itself, but the pointer check for *every* document in mergeFields() and
> > *every* document in mergeVectors().
>
> I like performance, but it does seem like anything that complicates
> the code (duplication and specialization) should result in an actual
> measurable performance increase.
>
> But in this specific case (I just looked at the code for mergeVectors)
> it makes sense because isDeleted() is essentially the *only* thing
> being done in the loop, and hence we can eliminate the loop entirely
> (an algorithmic change, not just eliminating a null pointer check
> per-document in the context of doing something else per-document).
>
> patch away ;-)
>
> -Yonik
> http://www.lucidimagination.com
>
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