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  1. Islandora
  2. ISLANDORA-2118

Undocumented behaviour using "Maximum returned values" in solr facet pages.



    • Type: Documentation
    • Status: Open
    • Priority: Minor
    • Resolution: Unresolved
    • Affects Version/s: 7.x-1.10
    • Fix Version/s: None
    • Component/s: Solr Facet Pages
    • Labels:


      In Solr Facet Pages, there's always been a "Maximum returned values" limit. It gets applied as the solr facet.limit [1] when populating the lists of facets. It's apparent that when you have a really large number of values, showing all of them might cause a really slow page load so you can shorten your lists by applying this limit.

      Here are the strange symptoms though:

      • The maximum facet limit doesn't appear to apply to individual letters, i.e. you could end up with more values returned under "A" than get returned under "ALL". 
      • It doesn't look like there's any pattern to what facets get "dropped" when this limit gets applied. 

      The reason for this is that for individual letters, two queries are done, e.g. myfield:A* and myfield:a* and the limit applies separately to each query. So you could find the first 1000 that start with A, and 1000 more that start with a, and get 2000 results under the "A" search. Also a potentially big chunk in the middle (the end of the A*'s) and at the end (the end of the a*'s) would be missing.

      This leads to a more existential question, do we really need this limiter? If you want a list of facets then you (I am guessing, also projecting) want a list of all the facets not the first however-many (or first however-many by each capitalization). As a user, I'd rather say "Show me facets with more than N entries (i.e. using facet.mincount [2])

      Is this feature important enough to keep or can it be retired/reworked into something different?


      [1] https://lucene.apache.org/solr/guide/6_6/faceting.html#Faceting-Thefacet.limitParameter

      [2] https://lucene.apache.org/solr/guide/6_6/faceting.html#Faceting-Thefacet.mincountParameter 


      Tagging Danny Joris and Jonathan Green who implemented this feature way back in 6.x. https://github.com/Islandora/islandora_solr_facet_pages/pull/3/files 




            rosiel Rosie Le Faive
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