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  1. Solr
  2. SOLR-6143

Bad facet counts from CollapsingQParserPlugin

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Details

    • Bug
    • Status: Resolved
    • Major
    • Resolution: Not A Problem
    • 4.8.1
    • None
    • query parsers
    • None
    • UNIX
      Tomcat 7.0.33
      SOLR 4.8.1
      16 GB RAM

    Description

      I'm noticing a very weird bug using the CollapsingQParserPlugin. We tried to use this plugin when we realized that faceting on the groups would take a ridiculous amount of time. To its credit, it works very quickly, however the facet counts that it gives are incorrect.

      We have a smallish index of about 200k documents with about with about 50k distinct groups within it.

      When we use the group implementation (&group=true&group.field=PrSKU&group.facet=true) which I believe this attempts to emulate, the facet counts are totally correct.

      When we use the field collapsing implementation, it will show an incorrect count for the non-filtered query, but when we go to the filtered query, the facet count corrects itself and matches the document count.

      Here are some SOLR responses:

      solrslave01:8983/index/select?q=classIDs:12&fl=PrSKU&fq=

      {!collapse%20field=PrSKU}&facet=true&facet.field=at_12_wood_tone

      The facet field will return

      <int name="Dark Wood">867</int>
      <int name="Medium Wood">441</int>
      <int name="Light Wood">253</int>

      When I actually apply a filter query like so:

      solrslave01:8983/index/select?q=classIDs:12&fl=PrSKU&fq={!collapse%20field=PrSKU}

      &facet=true&facet.field=at_12_wood_tone&fq=at_12_wood_tone:%22Light%20Wood%22

      I actually pull back 270 results and the facet updates itself with the correct number at the bottom

      <int name="Light Wood">270</int>
      <int name="Dark Wood">68</int>
      <int name="Medium Wood">66</int>

      If this were the same number pre and post filter query I would assume that it was simply my data that was bad, however I've pored over this for the better part of a day and I'm pretty sure it's the plugin. For reference, this field that I'm faceting on is a multiValued field, however I have noticed the exact same behavior on non multiValued fields (such as price).

      I can provide any other details you might need

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            Unassigned Unassigned
            dfennessey David Fennessey
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              Created:
              Updated:
              Resolved: