Maybe this can help you?
https://lucene.apache.org/solr/guide/7_5/distributed-requests.html#configuring-statscache-distributed-idf
On Mon, May 11, 2020 at 9:24 AM Spyros Kapnissis <ska...@gmail.com> wrote:
> HI all,
>
> On our current master/slave setup (no cloud), we use a a custom sorting
> function to get the first pass results (using the sort param), and then we
> use LTR for re-ranking. This works fine, i.e. re-ranking is applied on the
> topN, after sorting has completed and the order is correct.
>
> However, as we are migrating on SolrCloud (version 7.3.1) with multiple
> shards, this does not seem to work as expected. To my understanding, Solr
> collects the reranked results from the shards back on a single node to
> merge them, and then tries to re-apply sorting.
>
> We would expect the results to at least follow the sorting formula, even if
> this is not what we want. But this still not even the case, as the
> combination of the two (sorting + reranking) results in erratic ordering.
>
> Example result, where $sort_score is the sorting formula output, and score
> is the LTR re-ranked output:
>
> {"id": "152",
> "$sort_score": 17.38543,
> "score": 0.22140852
> },
> {"id": "2016",
> "$sort_score": 14.612957,
> "score": 0.19214153
> },
> { "id": "1523",
> "$sort_score": 14.4093275,
> "score": 0.26738763
> },
> { "id": "6704",
> "$sort_score": 13.956842,
> "score": 0.17357588
> },
> { "id": "6512",
> "$sort_score": 14.43907,
> "score": 0.11575622
> },
>
> We also tried with other simple re-rank queries apart from LTR, and the
> issue persisted.
>
> Could someone please help troubleshoot? Ideally, we would want to have the
> re-rank results merged on the single node, and not re-apply sorting.
>
> Thank you!
>
