Re: KnnQueries and result discrepancy between indexes with the same data

Indeed, the load order can influence Lucene's approximate nearest neighbor
search results.

If your two indexes load data sequentially and in the same order, then I
believe that you would get the same results. But we consider this an
implementation detail rather than a guarantee that Lucene should have.

On Thu, Sep 12, 2024 at 7:03 PM Marc Davenport
<[email protected]> wrote:

> Hello,
> I've been working on this personalization project using KNN queries and I
> have a couple questions but one is more pressing for me than the others.
>
> 1) Inconsistency between index instances:
> All of the same documents are loaded into different indexes. They may be
> loaded in different order, but the set of documents will be consistent when
> done.  I'm finding that when I ask for the 1000 knn documents I sometimes
> get inconsistent results between each index.  Results are always consistent
> from an individual instance.   If we assume I haven't made a mistake and
> the universe of documents are the same in all instances, can the document
> load order have an effect on what is considered the nearest neighbors?
>  What if I am processing updates to the index at different rates on each
> machine, but the end data is all the same?
>
> Thank you,
> Marc
>


-- 
Adrien