[SOLR-14662] Elevation with distributed search causes NPE

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 8.2
• Labels: distributed_search elevation
• Assignee: Unassigned
• Reporter: Marc Linden
• Created: 17/Jul/20 06:43
• Updated: 19/Aug/20 21:25

Description

When performing a distributed search with multiple shards having elevation configured where one ore more shards do have elevated results but others do not a NullPointerException is thrown.

We are using Solr 8.2 and have the QueryElevationComponent configured with "last-components" of the default search handler "/select". But the problem also occurs when using the explicit "/elevate" search handler.

  <requestHandler name="/select" class="solr.SearchHandler">
	...
	<arr name="last-components">
	  <str>elevator</str>
	</arr> 
  </requestHandler>
  ...
  <searchComponent name="elevator" class="solr.QueryElevationComponent" >
	<!-- pick a fieldType to analyze queries -->
	<str name="queryFieldType">string</str>
	<str name="config-file">elevate.xml</str>
  </searchComponent>

Steps to reproduce:

(1) Add entries to the elevate.xml of each core to elevate a specific document for the text "elevatedTerm

core1:
  <elevate>
    ...
    <query text="elevatedTerm"><doc id="core1docId1" /></query>
  </elevate>
core2:
  <elevate>
    ...
    <query text="elevatedTerm"><doc id="core2docId1" /></query>
  </elevate>

(2) Execute query (we use port 9983)

http://localhost:9983/solr/core1/select?q=elevatedTerm&lowercaseOperators=false&df=text_en&defType=edismax&fq=lang:en&shards=localhost:9983/solr/core1,localhost:9983/solr/core2&fl=[elevated],[shard],area,id&rows=10&start=0

As both shards have elevated documents for the requested "elevatedTerm" the search results are as expected:

response: {
  numFound: 5192,
  start: 0,
  maxScore: 1.9032197,
  docs: [{
    area: "press",
    id: "core1docId1",
    [elevated]: true,
    [shard]: "localhost:9983/solr/core1"
  }, {
    area: "products",
    id: "core2docId1",
    [elevated]: true,
    [shard]: "localhost:9983/solr/core2"
  }, {
    area: "press",
    id: "core1docId2",
    [elevated]: false,
    [shard]: "localhost:9983/solr/core1"
  },
  ...

(3) Remove the elevation entry for that "elevatedTerm" from one of the cores, e.g. via comment

core2:
  <elevate>
    ...
    <!--
    <query text="elevatedTerm"><doc id="core2docId1" /></query>
    -->
  </elevate>

(4) Reload the modified core: http://localhost:9983/solr/admin/cores?action=RELOAD&core=core2

(5) Request same query again and you get the NPE:

error: {
  trace: "java.lang.NullPointerException
         at org.apache.solr.handler.component.QueryComponent.unmarshalSortValues(QueryComponent.java:1068)
         at org.apache.solr.handler.component.QueryComponent.mergeIds(QueryComponent.java:917)
         at org.apache.solr.handler.component.QueryComponent.handleRegularResponses(QueryComponent.java:613)
         at org.apache.solr.handler.component.QueryComponent.handleResponses(QueryComponent.java:592)
         at org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:431)
         at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:199)
         at org.apache.solr.core.SolrCore.execute(SolrCore.java:2578)
         at org.apache.solr.servlet.HttpSolrCall.execute(HttpSolrCall.java:780)
         at org.apache.solr.servlet.HttpSolrCall.call(HttpSolrCall.java:566)
         at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:423)
         at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:350)
         at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1602)
         at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:540)
         ...

When adding the sort parameter with forceElevation=true to the query then a ClassCastException is thrown

http://localhost:9983/solr/core1/select?q=elevatedTerm&lowercaseOperators=false&df=text_en&defType=edismax&fq=lang:en&shards=localhost:9983/solr/core1,localhost:9983/solr/core2&fl=[elevated],[shard],area,id&rows=10&start=0&sort=area%20asc&forceElevation=true

java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
  at org.apache.solr.schema.FieldType.unmarshalStringSortValue(FieldType.java:1229)
  at org.apache.solr.schema.StrField.unmarshalSortValue(StrField.java:122)
  at org.apache.solr.handler.component.QueryComponent.unmarshalSortValues(QueryComponent.java:1092)
  at org.apache.solr.handler.component.QueryComponent.mergeIds(QueryComponent.java:917)
  at org.apache.solr.handler.component.QueryComponent.handleRegularResponses(QueryComponent.java:613)
  at org.apache.solr.handler.component.QueryComponent.handleResponses(QueryComponent.java:592)
  at org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:431)
  at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:199)
  at org.apache.solr.core.SolrCore.execute(SolrCore.java:2578)
  at org.apache.solr.servlet.HttpSolrCall.execute(HttpSolrCall.java:780)
  ...