Alessandro, I'll be doing some testing with the re-ranker as part of SOLR-9403 for Solr 6.3. I'll see if I can better understand the issue you're bringing up during the testing. I'll report back to this thread after I've done some testing.
Joel Bernstein http://joelsolr.blogspot.com/ On Fri, Sep 16, 2016 at 11:17 AM, Alessandro Benedetti < abenede...@apache.org> wrote: > In addition to that, I think the only way to solve this is to rely on the > aggregator node to actually re-rank after having aggregated. > > Cheer > > On Fri, Sep 9, 2016 at 11:48 PM, Alessandro Benedetti < > abenede...@apache.org > > wrote: > > > Let me explain further, > > let's assume a simple case when we have 2 shards. > > ReRankDocs =10 , rows=10 . > > > > Correct me if I am wrong Joel, > > What we would like : > > 1 page : top 10 re-scored > > 2 page: remaining 10 re-scored > > From page 3 the original scored docs. > > This is what is happening in a single sol instance if we put reRankDocs > to > > 20. > > > > Let's see with sharing : > > To get the first page we get top 10 ( re-scored) from shard1 and top 10 > > reranked for shard 2. > > Then the merged top 10 ( re-scored) will be calculated, and that is the > > page 1. > > > > But when we require the page 2, which means we additionally ask now : > > 20 docs to shard1, 10 re-scored and 10 not. > > 20 docs to shard2, 10 re-scored and 10 not. > > At this point we have 40 docs to merge and rank.. > > The docs with the original score can go at any position ( not necessarily > > the last 20) > > In the page 2 we can find potentially docs with the original score. > > This is even more likely if the scores are on differente scales (e.g. the > > re-scored 0<x<1 and original >100 ) . > > > > Am I right ? > > Did I make any wrong assumption so far ? > > > > Cheers > > > > > > On Fri, Sep 9, 2016 at 7:47 PM, Joel Bernstein <joels...@gmail.com> > wrote: > > > >> I'm not understanding where the inconsistency comes into play. > >> > >> The re-ranking occurs on the shards. The aggregator node will be sent > some > >> docs that have been re-scored and others that are not. But the sorting > >> should be the same as someone pages through the result set. > >> > >> > >> > >> Joel Bernstein > >> http://joelsolr.blogspot.com/ > >> > >> On Fri, Sep 9, 2016 at 9:28 AM, Alessandro Benedetti < > >> abenede...@apache.org> > >> wrote: > >> > >> > Hi guys, > >> > was just experimenting some reranker with really low number of rerank > >> docs > >> > ( 10= pageSize) . > >> > Let's focus on the distributed enviroment and the manual sharding > >> > approach. > >> > > >> > Currently what happens is that the reranking task is delivered by the > >> > shards, they rescore the docs and then send them back to the > aggregator > >> > node. > >> > > >> > If you want to rerank only few docs ( leaving the others with the > >> original > >> > score following), this can be done in a single Solr instance ( the > >> howmany > >> > logic manages that in the reranker) . > >> > > >> > What happens when you move to a distributed environment ? > >> > The aggregator will aggregate both rescored and original scored > >> documents, > >> > making the final ranking inconsistent. > >> > In the other hand if we make the rarankingDocs threshold dynamic ( to > >> adapt > >> > to start+rows) we can incur in the very annoying issue of having a > >> document > >> > sliding through the pages ( visible in the first page , then appearing > >> > again in the third ect ect). > >> > > >> > Any thought ? > >> > > >> > Cheers > >> > > >> > -- > >> > -------------------------- > >> > > >> > Benedetti Alessandro > >> > Visiting card : http://about.me/alessandro_benedetti > >> > > >> > "Tyger, tyger burning bright > >> > In the forests of the night, > >> > What immortal hand or eye > >> > Could frame thy fearful symmetry?" > >> > > >> > William Blake - Songs of Experience -1794 England > >> > > >> > > > > > > > > -- > > -------------------------- > > > > Benedetti Alessandro > > Visiting card : http://about.me/alessandro_benedetti > > > > "Tyger, tyger burning bright > > In the forests of the night, > > What immortal hand or eye > > Could frame thy fearful symmetry?" > > > > William Blake - Songs of Experience -1794 England > > > > > > -- > -------------------------- > > Benedetti Alessandro > Visiting card : http://about.me/alessandro_benedetti > > "Tyger, tyger burning bright > In the forests of the night, > What immortal hand or eye > Could frame thy fearful symmetry?" > > William Blake - Songs of Experience -1794 England >
