atris commented on issue #854: Shared PQ Based Early Termination for Concurrent 
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URL: https://github.com/apache/lucene-solr/pull/854#issuecomment-528247486
 
 
   > I thought that the follow up for LUCENE-8939 would be to allow the sharing 
of the minimum score (could be extended to a minimum FieldDoc) across slices ? 
Sharing the minimum score (or minimum FieldDoc) requires very little 
synchronization while a global priority queue seems much more costly. The other 
advantage is that we could add this ability in the current topdocs collector 
like we did for LUCENE-8939.
   
   @jimczi Yes, that is the third follow up PR that I am working on presently. 
The advantage of a shared priority queue is that it allows accurate count of 
hits. For eg, if a global hit is bested, then in a shared global priority 
queue, it can be replaced by the better hit. However, in the case where we do 
not share the priority queue, the hit which just got bested will be hard to 
replace (since it is in a thread local queue). The easiest way would be to let 
that hit live as well and collect the new hit, and then let `TopDocs.merge` do 
the job.
   
   I think that is a great approach to have and many usecases will be satisfied 
by that. However, for a case of very large hits or when the user wants precise 
counting, we might need to go with the global shared PQ. So, maybe we should 
have both approaches? WDYT?

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